Patrice ForgetpersName, Céline KhalifapersName, Jean‐Philippe DefourpersName, Dominique LatinnepersName, Marie-Cécile Van PelpersName, Marc De KockpersName (2017date). “What is the normal value of the neutrophil-to-lymphocyte ratio?.” BMC Research Notestitle·venue.
Object of study — the neutrophil-to-lymphocyte ratio - A MARKER IN WIDE CLINICAL USE WITH NO REFERENCE RANGE, whose cut-offs had been taken from the diseased populations it was meant to identify
Research question — what values of the NLRterm occur in an adult, non-geriatric population without acute illness or chronic debilitating disease
Contribution — an upper and lower reference limit for the NLRterm derived from healthy subjects rather than from patients, with an independent validation cohort
phenomenon · claim-type · cross-domain-transfer · mechanism · claim-relation · replication-status · limitation — grounded in the full text| phenomenon | a ratio of two routinely-counted cell populations used as an inflammatory index, whose distribution in health had not been described — “Neutrophil-to-lymphocyte ratio (NLR) is a simple parameter to assess easily the inflammatory status of a subject.” | |
| claim-type | existence — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | |
| method — evidence | — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | |
| object of study — evidence | — “However, which NLR value is correlated with a higher risk for these patients? Which cut-off value, for the NLR, will discriminate normal from abnormal results? Different values of NLR, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available. Therefore, there is a need for reference values to progress in the use of this marker.” | |
| research question — evidence | — “The aim of this study is to determine the limits of the values of the NLR that are observed in an adult, non-geriatric population, without any acute illness and/or chronic debilitating disease.” | |
| contribution — evidence | — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | |
| mechanism | THE CUT-OFF WAS DERIVED FROM THE POPULATION IT WAS MEANT TO DISTINGUISH, AND THE PAPER SAYS SO: `none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves`. A marker whose whole job is separating sick from well, thresholded from the median of the sick — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | mechanisms[0] |
| mechanism | and the field had no single number at all: `Different values of NLR, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available`. Three sources of variation named in one sentence - the value, the method and the population — “However, which NLR value is correlated with a higher risk for these patients? Which cut-off value, for the NLR, will discriminate normal from abnormal results? Different values of NLR, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available. Therefore, there is a need for reference values to progress in the use of this marker.” | mechanisms[1] |
| mechanism | the correction is a change of REFERENCE CLASS, not of statistic: `In contrast with these studies, we found here limits based on a sample of an active adult population in good health`. Same arithmetic, different people, and that is the whole paper — “In contrast with these studies, we found here limits based on a sample of an active adult population in good health. This value can be used as a cut-off to differentiate patients that are in the range of a population in good health or not” | mechanisms[2] |
| extends | the prognostic NLR literature in cardiology, oncology and infection, which established the marker's usefulness without ever establishing its normal range — “There are a lot of examples in the literature of the interest of the NLR as an independent prognostic factor of morbidity and mortality in several conditions, such as cancers and cardiovascular diseases. NLR is also useful in the prediction and the detection of inflammatory and infectious conditions, and their postoperative complications” | claim_relations[0] |
| contradicts | the practice of setting an NLR cut-off from the median, upper quartile or ROC of the diseased sample - contradicted as a SOURCE, not as arithmetic — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | claim_relations[1] |
| sense | `normal value` - IN THIS PAPER, THE MEAN +/- 1.96 SD OF A WORKING POPULATION, 0.78 to 3.53. Not a physiological threshold, not an outcome-derived cut-off: a distribution of people who were at work and had blood taken — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | senses[0] |
| sense | `normal value` IN THE LITERATURE IT CORRECTS - `the median, higher quartile or values determined by the use of receiver-operating curves`, computed inside the diseased sample. THE SAME PHRASE NAMES A PROPERTY OF THE HEALTHY IN ONE PLACE AND A PROPERTY OF THE SICK IN THE OTHER — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | senses[1] |
| sense | `good health` - OPERATIONALLY, EMPLOYABILITY PLUS AN ABSENCE OF RECORDS. `in good health, permitting a full time job without restriction`, with `No information ... about habits ... and possible comorbidities`. The second cohort uses a stricter sense - `carefully selected on the basis of the absence of any chronic disease or substance/medications` - so the paper carries two senses of health and validates one against the other — “Our goal is to identify the higher boundary observed in a population in good health, but not excluding non-debilitating disease, tobacco use or oral contraception. Therefore, it would be important to compare the results to those obtained in a second, and independent, sample (n = 29) of normal controls, strictly selected on the basis of perfect health, coming from an historical cohort. This cohort was used during the process of the calibration of the blood analyser. The subjects in this second cohort were in the same range of age, but, after interrogation and examination, carefully selected on the basis of the absence of any chronic disease or substance/medications (abuse, including tobacco use).” | senses[2] |
| sense | `NLR` - `The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR`. One sentence, one division, and no cue list the gate holds can see it - `calculated as` is on MEASUREMENT and `to calculate` is not — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | senses[3] |
| control | a second, independent cohort of 29 subjects selected on strict health criteria - no chronic disease, no substance or medication use including tobacco - run on four further analysers — held — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” — rules out the objection that the main cohort's limits reflect its own unscreened population: 'no NLR assessed in the validation series is OUT OF THE PROPOSED LIMITS' — “Our goal is to identify the higher boundary observed in a population in good health, but not excluding non-debilitating disease, tobacco use or oral contraception. Therefore, it would be important to compare the results to those obtained in a second, and independent, sample (n = 29) of normal controls, strictly selected on the basis of perfect health, coming from an historical cohort. This cohort was used during the process of the calibration of the blood analyser. The subjects in this second cohort were in the same range of age, but, after interrogation and examination, carefully selected on the basis of the absence of any chronic disease or substance/medications (abuse, including tobacco use).” | controls[0] |
| control | a stated power calculation for the validation cohort - 'to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29' — held — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” — rules out the objection that n=29 was chosen for convenience; the number is derived and the derivation is printed — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | controls[1] |
| control | NLR sample stability over 48 h — held — “NLR sample stability over 48 h was assessed; there was no significant variation over this time period and the NLR was then considered stable.” — rules out pre-analytical drift as a source of the observed spread - 'there was no significant variation over this time period and the NLR was then considered stable' — “NLR sample stability over 48 h was assessed; there was no significant variation over this time period and the NLR was then considered stable.” | controls[2] |
| control | whether the reference limits hold outside an adult, non-geriatric, occupationally-screened, unrecorded-for-smoking population — absent-declared-unreported — “However, in the sample of normal control, we see that the 95% CI permits to say that it is very improbable that normal controls will have a NLR value of 3.5. Nevertheless, it seems logical to interpret cautiously this type of parameter (like any other), in a clinical context to adjust the interpretation, even if based on data coming from a comparable population” — rules out nothing, and the paper lists the gaps itself: 'Age is certainly a limit ... we did not have the complete documentation of substance use/abuse ... Ethnic group origins, sex and season of assessment have not been included' — “Can it be used in other populations that this from which this sample is coming? Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years). Additionally, we did not have the complete documentation of substance use/abuse, like tobacco or oral contraceptive. Ethnic group origins, sex and season of assessment have not been included in the analyses.” | controls[3] |
| weight | the prognostic NLR literature in cardiology, oncology and infection, which established the marker's usefulness without ever establishing its normal range — 0.85 — “There are a lot of examples in the literature of the interest of the NLR as an independent prognostic factor of morbidity and mortality in several conditions, such as cancers and cardiovascular diseases. NLR is also useful in the prediction and the detection of inflammatory and infectious conditions, and their postoperative complications” | claim_relations[0] |
| weight | the practice of setting an NLR cut-off from the median, upper quartile or ROC of the diseased sample - contradicted as a SOURCE, not as arithmetic — 0.7 — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | claim_relations[1] |
| note | Neutrophil-to-lymphocyte ratio (NLR) —is-a→ parameter — 'a SIMPLE parameter to assess easily the inflammatory status of a subject' - the simplicity is the paper's own emphasis and is why the ratio spread through clinical use before anybody established its range — “Neutrophil-to-lymphocyte ratio (NLR) is a simple parameter to assess easily the inflammatory status of a subject.” | concept_edges[0] |
| weight | Neutrophil-to-lymphocyte ratio (NLR) —is-a→ parameter — 0.95 — “Neutrophil-to-lymphocyte ratio (NLR) is a simple parameter to assess easily the inflammatory status of a subject.” | concept_edges[0] |
| outcome | control — held — “Our goal is to identify the higher boundary observed in a population in good health, but not excluding non-debilitating disease, tobacco use or oral contraception. Therefore, it would be important to compare the results to those obtained in a second, and independent, sample (n = 29) of normal controls, strictly selected on the basis of perfect health, coming from an historical cohort. This cohort was used during the process of the calibration of the blood analyser. The subjects in this second cohort were in the same range of age, but, after interrogation and examination, carefully selected on the basis of the absence of any chronic disease or substance/medications (abuse, including tobacco use).” — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” | controls[0] |
| outcome | control — held — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” | controls[1] |
| outcome | control — held — “NLR sample stability over 48 h was assessed; there was no significant variation over this time period and the NLR was then considered stable.” | controls[2] |
| outcome | control — absent-declared-unreported — “Can it be used in other populations that this from which this sample is coming? Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years). Additionally, we did not have the complete documentation of substance use/abuse, like tobacco or oral contraceptive. Ethnic group origins, sex and season of assessment have not been included in the analyses.” — “However, in the sample of normal control, we see that the 95% CI permits to say that it is very improbable that normal controls will have a NLR value of 3.5. Nevertheless, it seems logical to interpret cautiously this type of parameter (like any other), in a clinical context to adjust the interpretation, even if based on data coming from a comparable population” | controls[3] |
| limitation | THE PAPER'S OWN HEADLINE NUMBER IS STATED TWO WAYS. The upper reference limit is the entire contribution, and it appears FIVE TIMES AS 3.53 - abstract, Results, Table 1 and both Conclusions - and ONCE AS 3.58, in the Discussion: `the NLR values, in a sample of 413 active subjects in good health, are between 0.78 and 3.58`. VERIFIED AS THE PUBLISHER'S TEXT, not the pipeline's: `3.58` occurs once in the source XML and `3.53` five times, same file, same renderer — “We show here that the NLR values, in a sample of 413 active subjects in good health, are between 0.78 and 3.58. We confirm that no normal control (selected on the basis of the absence of any comorbidities and substance abuse, including tobacco) exceeded this range.” | limitations[0] |
| limitation | AND `HEALTHY` IS DEFINED BY WHAT WAS NOT RECORDED: the samples come from `workers potentially exposed to X-rays or any others ionizing radiation`, anonymised such that `No information was therefore available about habits (e.g. tobacco use) and possible comorbidities (e.g. obesity or vascular disease)`. The reference class for normal is `held a full-time job and nothing was written down` — “Blood samples were obtained for routine hematologic control in workers potentially exposed to X-rays or any others ionizing radiation. Samples were treated anonymously, including sex and date of birth. No information was therefore available about habits (e.g. tobacco use) and possible comorbidities (e.g. obesity or vascular disease).” | limitations[1] |
| limitation | and health is operationalised as EMPLOYABILITY: `these subjects were in good health, permitting a full time job without restriction, and without any active disease ... and are representative of the population as a whole` - a representativeness claim made for a working-age, occupationally-screened sample — “Typically, these subjects were in good health, permitting a full time job without restriction, and without any active disease, including cancer and infectious disease and are representative of the population as a whole.” | limitations[2] |
| limitation | the paper lists what its own range cannot cover: `Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years) ... Ethnic group origins, sex and season of assessment have not been included in the analyses` — “Can it be used in other populations that this from which this sample is coming? Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years). Additionally, we did not have the complete documentation of substance use/abuse, like tobacco or oral contraceptive. Ethnic group origins, sex and season of assessment have not been included in the analyses.” | limitations[3] |
| limitation | FIVE ANALYSERS, FIVE MEANS - 1.65, 1.76, 1.86, 1.68, 1.69 - a 13% spread reported as agreement: `the NLR values are in the same range, whichever the used analyzer`. True of the RANGE and not of the mean, and the reference limits come from one instrument — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” | limitations[4] |
finding · quantity · variable · definition · key-term — grounded in the full text| finding | — “However, which NLR value is correlated with a higher risk for these patients? Which cut-off value, for the NLR, will discriminate normal from abnormal results? Different values of NLR, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available. Therefore, there is a need for reference values to progress in the use of this marker.” | content_tags.findings[0] |
| finding | — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | content_tags.findings[1] |
| finding | — “In contrast with these studies, we found here limits based on a sample of an active adult population in good health. This value can be used as a cut-off to differentiate patients that are in the range of a population in good health or not” | content_tags.findings[2] |
| finding | — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” | content_tags.findings[3] |
| finding | — “We show here that the NLR values, in a sample of 413 active subjects in good health, are between 0.78 and 3.58. We confirm that no normal control (selected on the basis of the absence of any comorbidities and substance abuse, including tobacco) exceeded this range.” | content_tags.findings[4] |
| finding | — “Blood samples were obtained for routine hematologic control in workers potentially exposed to X-rays or any others ionizing radiation. Samples were treated anonymously, including sex and date of birth. No information was therefore available about habits (e.g. tobacco use) and possible comorbidities (e.g. obesity or vascular disease).” | content_tags.findings[5] |
| finding | — “Typically, these subjects were in good health, permitting a full time job without restriction, and without any active disease, including cancer and infectious disease and are representative of the population as a whole.” | content_tags.findings[6] |
| finding | — “Our goal is to identify the higher boundary observed in a population in good health, but not excluding non-debilitating disease, tobacco use or oral contraception. Therefore, it would be important to compare the results to those obtained in a second, and independent, sample (n = 29) of normal controls, strictly selected on the basis of perfect health, coming from an historical cohort. This cohort was used during the process of the calibration of the blood analyser. The subjects in this second cohort were in the same range of age, but, after interrogation and examination, carefully selected on the basis of the absence of any chronic disease or substance/medications (abuse, including tobacco use).” | content_tags.findings[7] |
| finding | — “Anticoagulated whole blood from routine controls were processed on Sysmex XE2100 [TOA Medical Electronics, Kobe, Japan], Normal controls were analysed on Sysmex XN2000 (TOA Medical electronics Co, Kobe, Japan), Advia 2120 (Bayer Diagnostics, Tarritown, NY, USA), DXH800 (Beckman Coulter, Miami, FL USA), Cell-Dyn Sapphire (Abbott Diagnostics Santa Clara, CA, USA) for the determination of the complete blood cell counts and differential counts of leukocytes.” | content_tags.findings[8] |
| finding | — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | content_tags.findings[9] |
| finding | — “Can it be used in other populations that this from which this sample is coming? Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years). Additionally, we did not have the complete documentation of substance use/abuse, like tobacco or oral contraceptive. Ethnic group origins, sex and season of assessment have not been included in the analyses.” | content_tags.findings[10] |
| finding | — “However, in the sample of normal control, we see that the 95% CI permits to say that it is very improbable that normal controls will have a NLR value of 3.5. Nevertheless, it seems logical to interpret cautiously this type of parameter (like any other), in a clinical context to adjust the interpretation, even if based on data coming from a comparable population” | content_tags.findings[11] |
| finding | — “NLR sample stability over 48 h was assessed; there was no significant variation over this time period and the NLR was then considered stable.” | content_tags.findings[12] |
| finding | — “There are a lot of examples in the literature of the interest of the NLR as an independent prognostic factor of morbidity and mortality in several conditions, such as cancers and cardiovascular diseases. NLR is also useful in the prediction and the detection of inflammatory and infectious conditions, and their postoperative complications” | content_tags.findings[13] |
| quantity | the upper reference limit - stated five times in the paper, and once as 3.58 — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | content_tags.quantities[0] |
| value source note | quantity — THE DESCRIPTION DRAWS ON THE PAPER BEYOND THIS QUOTE: the 3.58 is the Discussion's version of the upper limit ('are between 0.78 and 3.58.'). The quote gives 3.53; the description records that the paper prints both. | content_tags.quantities[0] |
| quantity | the Discussion's version of the same upper limit; the publisher's text, verified against the source XML — “We show here that the NLR values, in a sample of 413 active subjects in good health, are between 0.78 and 3.58. We confirm that no normal control (selected on the basis of the absence of any comorbidities and substance abuse, including tobacco) exceeded this range.” | content_tags.quantities[1] |
| quantity | the lower reference limit, consistent everywhere in the paper — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | content_tags.quantities[2] |
| quantity | subjects in the main cohort, from a workplace health-care prevention programme — “Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLR is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLR values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLR assessed in the validation series is out of the proposed limits.” | content_tags.quantities[3] |
| quantity | subjects in the validation cohort - 28 were required by the power calculation — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | content_tags.quantities[4] |
| variable | NLR — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | content_tags.variables[0] |
| definition | NLR — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | content_tags.definitions[0] |
| definition | normal NLR values — “We have identified that normal NLR values in an adult, non-geriatric, population in good health are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLR, until now lacking.” | content_tags.definitions[1] |
| definition | good health — “Typically, these subjects were in good health, permitting a full time job without restriction, and without any active disease, including cancer and infectious disease and are representative of the population as a whole.” | content_tags.definitions[2] |
| concept | Neutrophil-to-lymphocyte ratio (NLR) — not defined in this paper's own words; the absolute neutrophil count divided by the absolute lymphocyte count — “Neutrophil-to-lymphocyte ratio (NLR) is a simple parameter to assess easily the inflammatory status of a subject.” | concepts[0] |
| concept | NLR — not defined in this paper's own words; the ratio as named throughout the paper — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | concepts[1] |
| concept | parameter — not defined in this paper's own words; the kind of thing the paper says the NLR is - 'a simple parameter to assess easily the inflammatory status of a subject' — “Neutrophil-to-lymphocyte ratio (NLR) is a simple parameter to assess easily the inflammatory status of a subject.” | concepts[2] |
| concept | absolute neutrophil count — not defined in this paper's own words; the numerator — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | concepts[3] |
| concept | absolute lymphocyte count — not defined in this paper's own words; the denominator — “The absolute neutrophil count was divided by the absolute lymphocyte count to calculate the NLR.” | concepts[4] |
| concept | reference values — not defined in this paper's own words; limits derived from a population in good health - what the paper says the field needed and did not have — “However, which NLR value is correlated with a higher risk for these patients? Which cut-off value, for the NLR, will discriminate normal from abnormal results? Different values of NLR, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available. Therefore, there is a need for reference values to progress in the use of this marker.” | concepts[5] |
| concept | receiver-operating curves — not defined in this paper's own words; the outcome-driven way earlier studies chose a cut-off, inside the diseased sample — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | concepts[6] |
| concept | normal controls — not defined in this paper's own words; the 29 strictly-selected subjects of the validation cohort, screened for chronic disease and substance use — “Nevertheless, none of these studies based their cut-off on data coming from population in good health, and none on data coming from normal controls. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curves (to predict the occurrence of a condition, e.g. cancer recurrence of infection)” | concepts[7] |
| concept | good health — not defined in this paper's own words; employability without restriction and no recorded active disease - the main cohort's criterion — “Typically, these subjects were in good health, permitting a full time job without restriction, and without any active disease, including cancer and infectious disease and are representative of the population as a whole.” | concepts[8] |
| concept | log-normal distribution — not defined in this paper's own words; the distributional assumption that makes mean +/- 1.96 SD the right interval here — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | concepts[9] |
| log-normal distribution | — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | content_tags.statistics[0] |
| 95% confidence limits | — “For the statistical analyses, laboratory parameters fit a log-normal distribution. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controls would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation.” | content_tags.statistics[1] |
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Abstract. Background Neutrophil-to-lymphocyte ratio (NLR)term has proven its prognostic value in cardiovascular diseases, infections, inflammatory diseases and in several types of cancers. However, no cut-off has been proposed on the basis of reference valuesterm coming from healthy population. Methods Routine blood samples were obtained (n = 413) from workers (age: median 38, range: 21–66 years) involved in a health care prevention program, to determine means, standard deviations (SDs), 95% confidence intervals (95% CI), percentiles P2.5 and P97.5. A second independent sample of healthy volunteers is compared (n = 29). Results The mean NLRterm is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLRterm values are in the same range, whichever the used analyzer. No NLRterm assessed in the validation series is out of the proposed limits. Conclusions We have identified that the normal NLR valuesterm·def in an adult, non-geriatric, population in good healthterm are between 0.78 and 3.53. These data will help to define the normal values of the NLRterm. Electronic supplementary material The online version of this article (doi:10.1186/s13104-016-2335-5) contains supplementary material, which is available to authorized users. Background Neutrophil-to-lymphocyte ratio (NLR)term is a simple parameterterm to assess easily the inflammatory status of a subject. It has proven its usefulness in the stratification of mortality in major cardiac events [ 1 , 2 ], as a strong prognostic factor in several types of cancers [ 3 – 10 ], or as a predictor and a marker of inflammatory or infectious pathologies (such is pediatric appendicitis) and postoperative complications [ 11 , 12 ]. However, which NLRterm value is correlated with a higher risk for these patients? Which cut-off value, for the NLRterm, will discriminate normal from abnormal results? Different values of NLRterm, with different methods, in different populations (cancerous or not) are cited in the literature. And finally, no universal value is currently available. Therefore, there is a need for reference valuesterm to progress in the use of this marker. The aim of this study is to determine the limits of the values of the NLRterm that are observed in an adult, non-geriatric population, without any acute illness and/or chronic debilitating disease. Methods Subjects and data collection With the agreement of the Ethical Committee (ref. 2014/451, Chairperson: Prof. Jean-Marie Maloteaux, av. Hippocrate, 55-14, 1200 Brussels), we performed the following analyses. Blood samples for routine control between October 2011 and 2012 were identified from 413 participants of the health care prevention program for workers. Considering the analysis as retrospective, given the fact that the samples were pre-collected and treated anonymously, the Ethical Committee gave a waiver for individual consent. Consequently, no written informed consent for participation in the study was obtained from participants. Median age was 38 years (range: 21–66 years). Typically, these subjects were in good healthterm, permitting a full time job without restriction, and without any active disease, including cancer and infectious disease and are representative of the population as a whole. Blood samples were obtained for routine hematologic control in workers potentially exposed to X-rays or any others ionizing radiation. Samples were treated anonymously, including sex and date of birth. No information was therefore available about habits (e.g. tobacco use) and possible comorbidities (e.g. obesity or vascular disease). Normal controlsterm Our goal is to identify the higher boundary observed in a population in good healthterm, but not excluding non-debilitating disease, tobacco use or oral contraception. Therefore, it would be important to compare the results to those obtained in a second, and independent, sample (n = 29) of normal controlsterm, strictly selected on the basis of perfect health, coming from an historical cohort. This cohort was used during the process of the calibration of the blood analyser. The subjects in this second cohort were in the same range of age, but, after interrogation and examination, carefully selected on the basis of the absence of any chronic disease or substance/medications (abuse, including tobacco use). Samples analyses Anticoagulated whole blood from routine controls were processed on Sysmex XE2100 [TOA Medical Electronics, Kobe, Japan], Normal controlsterm were analysed on Sysmex XN2000 (TOA Medical electronics Co, Kobe, Japan), Advia 2120 (Bayer Diagnostics, Tarritown, NY, USA), DXH800 (Beckman Coulter, Miami, FL USA), Cell-Dyn Sapphire (Abbott Diagnostics Santa Clara, CA, USA) for the determination of the complete blood cell counts and differential counts of leukocytes. The absolute neutrophil countterm was divided by the absolute lymphocyte countterm to calculate the NLRterm. Statistical analyses For the statistical analyses, laboratory parametersterm fit a log-normal distributionterm. Logarithmic conversion was therefore used for calculating means and 95% confidence limits (95% CI) are presented as arithmetic mean ± 1.96 SD (with their 95% CI). Power analysis shows that, to test the hypothesis that <2.5% of the normal controlsterm would be out of the proposed limits, 28 subjects are needed. It is the reason why we included 29 blood samples of the historical cohort for the external validation. All the analyses were performed with STATISTICA (data analysis software system, version 7, Statsoft Inc. 2004, Tulsa). Results Results coming from the blood samples of the 413 subjects of the main cohort are presented in Table 1 . Briefly, the mean NLRterm is 1.65 [±1.96 SD: 0.78–3.53] (95% CI [0.75–0.81] and [3.40–3.66]). In the second cohort (healthy control), the NLRterm values are in the same range, whichever the used analyzer (Table 1 ). Consequently, no NLRterm assessed in the validation series is out of the proposed limits. Table 1 Neutrophil-to-lymphocyte ratios obtained in two cohort of subjects (n = 413 and n = 29) on five blood analysers, expressed in mean, SD and lower/upper limits of the mean ± 1.96 SD range (and their 95% CI) Mean SD Lower limit 95% CI Upper limit 95% CI Initial cohort (n = 413) Sysmex XE2100 1.65 1.47 0.78 0.75 0.81 3.53 3.40 3.66 Control cohort (n = 29) Beckman DXH800 1.76 1.42 0.89 0.78 1.02 3.49 3.06 3.97 Siemens 2120i 1.86 1.39 0.97 0.86 1.10 3.54 3.13 4.00 Abbott SAPHYR 1.68 1.42 0.85 0.74 0.96 3.32 2.92 3.79 Sysmex XN2000 1.69 1.37 0.91 0.81 1.03 3.12 2.77 3.52 NLRterm sample stability over 48 h was assessed; there was no significant variation over this time period and the NLRterm was then considered stable. Discussion We show here that the NLRterm values, in a sample of 413 active subjects in good healthterm, are between 0.78 and 3.58. We confirm that no normal controlterm (selected on the basis of the absence of any comorbidities and substance abuse, including tobacco) exceeded this range. There are a lot of examples in the literature of the interest of the NLRterm as an independent prognostic factor of morbidity and mortality in several conditions, such as cancers and cardiovascular diseases. NLRterm is also useful in the prediction and the detection of inflammatory and infectious conditions, and their postoperative complications [ 11 , 12 ]. Nevertheless, none of these studies based their cut-off on data coming from population in good healthterm, and none on data coming from normal controlsterm. Some of these studies chose their cut-off value on the basis of the median, higher quartile or values determined by the use of receiver-operating curvesterm (to predict the occurrence of a condition, e.g. cancer recurrence of infection) [ 13 – 15 ]. In contrast with these studies, we found here limits based on a sample of an active adult population in good healthterm. This value can be used as a cut-off to differentiate patients that are in the range of a population in good healthterm or not [ 16 ]. Can it be used in other populations that this from which this sample is coming? Age is certainly a limit, as we tested only adult, non-geriatric, subjects (between 21 and 66 years). Additionally, we did not have the complete documentation of substance use/abuse, like tobacco or oral contraceptive. Ethnic group origins, sex and season of assessment have not been included in the analyses. However, in the sample of normal controlterm, we see that the 95% CI permits to say that it is very improbable that normal controlsterm will have a NLRterm value of 3.5. Nevertheless, it seems logical to interpret cautiously this type of parameterterm (like any other), in a clinical context to adjust the interpretation, even if based on data coming from a comparable population (Additional file 1 ). Conclusions We have identified that normal NLR valuesterm·def in an adult, non-geriatric, population in good healthterm are between 0.78 and 3.53. These data may help the researcher as the clinician searching for a cut-off for the NLRterm, until now lacking.