|Year : 2019 | Volume
| Issue : 5 | Page : 419-423
Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in chronic periodontitis before and after nonsurgical therapy
Anirudh Balakrishna Acharya1, Indrajith Padukone Shetty2, Shrinidhi Jain1, Ibbani Padakannaya3, Swetha Acharya4, Leena Shettar1, Srinath Thakur1
1 Department of Periodontics, S.D.M. College of Dental Sciences and Hospital, SDM University, Dharwad, Karnataka, India
2 Private Practice, Hyderabad, Telangana, India
3 Private Practice, Bengaluru, Karnataka, India
4 Department of Oral Pathology, S.D.M. College of Dental Sciences and Hospital, SDM University, Dharwad, Karnataka, India
|Date of Submission||08-Oct-2018|
|Date of Acceptance||21-Jun-2019|
|Date of Web Publication||29-Aug-2019|
Dr. Anirudh Balakrishna Acharya
Department of Periodontics, S.D.M. College of Dental Sciences and Hospital, Dharwad - 580 009, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Various biomarkers have been evaluated for understanding the systemic inflammatory response (SIR) to periodontitis. Hematological markers have been reported to be useful biomarkers in a variety of diseases, including periodontal diseases. The role of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in periodontitis and their possible role in the SIR are not extensively documented. Therefore, this study assessed NLR and PLR in chronic periodontitis (CP) patients before and after periodontal treatment, which to the best of knowledge has not been reported in the literature. Materials and Methods: Sixty participants were grouped as systemically and periodontally healthy (H) (n = 30) and with CP (n = 30). Plaque index, gingival index, probing pocket depth, clinical attachment loss, leukocyte counts, platelet (PLT) counts, NLR, and PLR were estimated at baseline and also after treatment in the CP group. NLR was calculated as total neutrophil count/absolute lymphocyte count, and PLR was calculated as total PLT count/absolute lymphocyte count. The data were statistically analyzed. Results: Periodontal parameters differed significantly between groups H and CP at baseline and posttreatment. A pair-wise comparison of NLR and PLR between CP patients at baseline and posttreatment was significant. Correlation analyses were not remarkable. Receiver operating characteristics analyses provided significant NLR and PLR predictive cutoff values to differentiate between CP patients at baseline and posttreatment. Conclusion: NLR and PLR may serve as potential biomarkers of the SIR to CP to bridge the association between periodontal and systemic conditions.
Keywords: Blood platelets, chronic periodontitis, dental, lymphocytes, neutrophils, scaling
|How to cite this article:|
Acharya AB, Shetty IP, Jain S, Padakannaya I, Acharya S, Shettar L, Thakur S. Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in chronic periodontitis before and after nonsurgical therapy. J Indian Soc Periodontol 2019;23:419-23
|How to cite this URL:|
Acharya AB, Shetty IP, Jain S, Padakannaya I, Acharya S, Shettar L, Thakur S. Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in chronic periodontitis before and after nonsurgical therapy. J Indian Soc Periodontol [serial online] 2019 [cited 2022 Aug 15];23:419-23. Available from: https://www.jisponline.com/text.asp?2019/23/5/419/265536
| Introduction|| |
Chronic periodontitis (CP) is described as an infectious disease resulting in the inflammation of the supporting structures of the teeth with connective tissue attachment loss and alveolar bone loss. Inflammation is the driving phenomenon in CP. The inflammatory cells have an important role in the aggravation or resolution of CP. The role of neutrophils in the innate inflammatory response, lymphocytes in adaptive immunity , is known. Platelets (PLT) deliver important mediators and sustain a local inflammatory response. Leukocytes and PLT may be elevated in numbers as a response to periodontal pathogens  and are likely to decrease after periodontal treatment., Changes in peripheral blood parameters have been reported in periodontal diseases and are associated with a systemic inflammatory response (SIR).,,,, These include white blood cells (WBCs), red blood cells, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red-cell distribution width, PLT, mean platelet volume (MPV), and platelet large cell ratio index (PLCRi).
It is understood that neutrophils and lymphocytes are key players in inflammation and immune responses. PLT have important functions (other than in blood clotting mechanisms) in inflammation because of their involvement in the formation of PLT-leukocyte aggregate (by expressing PLT P-selectin), mediating T-cell immune responses, producing a variety of pro-inflammatory cytokines, as well as synchronizing innate and adaptive immunity. For example, to assess PLT function, MPV is obtained with routine blood counts in automated hemograms. MPV and MPV/PLT is considered a reliable biomarker in inflammatory conditions., The PLCRi is also a dependable estimator, in conjunction with PLT volume indices of diseases such as hypertension, atherosclerosis, and diabetes.
Neutrophil-to-lymphocyte ratio (NLR) and platelet-to- lymphocyte ratio (PLR) are additions to the list of the aforementioned markers. NLR and PLR are calculated from complete blood count with differential. It is an economical, simple to acquire, and convenient to perform laboratory test. NLR is considered to mirror a balance between the innate and adaptive immune mechanisms. Pro-inflammatory cytokines may be increased if NLR is elevated.,, PLR is a useful parameter for the SIR  and contributes to clinical symptoms. A combination of NLR and PLR are effective markers reflecting the inflammatory response which are also considered prognostic markers or predictors of systemic diseases and may be associated with increased levels of pro-inflammatory mediators resulting in a heightened inflammatory status.,,,,,,,,,, Hence, it is hypothesized that NLR-PLR variation has a negative impact in disease. This aspect of NLR and PLR with regard to periodontal diseases has not been addressed extensively in the literature.
To the best of knowledge, NLR and PLR have not been evaluated as a systemic marker of periodontal disease before and after scaling and root planing (SRP). The aim of this study was to estimate NLR and PLR in CP before and after SRP to evaluate their possible role as a marker of periodontal disease.
| Materials and Methods|| |
Sixty volunteers (healthy individuals and patients visiting our institution and associated hospital) were recruited for this study after an ethical clearance was obtained from the Institution's Ethical Committee. A written informed consent was obtained from all participants, and the study was in accordance with the World Medical Association Declaration of Helsinki.
Age between 18 and 55 years; CP defined as the presence of at least 20 natural teeth with generalized (i.e., >30% of the sites examined) probing pocket depths (PPD) of ≥4 mm and clinical attachment level (CAL) of ≥2 mm (stent as reference); positive for bleeding on probing; radiographic evidence of bone loss.
Patients with systemic diseases; known allergies; tobacco users; pregnant, lactating women, women in menopause; patients with immunosuppressed conditions such as systemic lupus erythematosus and rheumatoid arthritis; periodontal therapy in the last 6 months; antibiotic and/or anti-inflammatory drug regimen before the study; and teeth with calculus or cervical caries or without a clinical tooth crown (CAL not measured).
A medical and dental history was recorded, and the participants were subjected to a periodontal examination. On the basis of their plaque index (PlI), gingival index (GI), PPD, CAL, and radiographic (long cone, paralleling technique) evidence of bone loss, the participants were grouped as thirty healthy individuals (H) and thirty CP patients. PPD and CAL assessments were conducted with a UNC-15 periodontal probe (Hu-Friedy ® Manufacturing Inc., Chicago, IL, USA). Measurements were made at six different sites of each tooth present: mesiobuccal, midbuccal, distobuccal, midlingual, distolingual, and lingual. The CP patients were grouped as CP-BL (CP at baseline) and CP-PT (CP posttreatment). The mean value of the measurements was taken into consideration for each patient.
Blood was drawn and collected from the antecubital fossa of the arm using a 21 gauge syringe by a hematology laboratory staff into a vacutainer incrementally in small volumes. The WBCs and PLT were estimated using pocH-100i automated hematology analyzer (Sysmex Corporation, Kobe, Japan), and the differential count was calculated.
Calculation of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio
NLR was calculated as total neutrophil count/absolute lymphocyte count, and PLR was calculated as total PLT count/absolute lymphocyte count, i.e., NLR was calculated as the ratio of neutrophils to lymphocytes and PLR was calculated as the ratio of PLT to lymphocytes.
All the participants were provided oral hygiene instructions at baseline. The CP patients received SRP with the use of an ultrasonic scaler (Electromedical Systems EMS, Nyon, Switzerland), manual instruments (Hu-Friedy ® Manufacturing Inc., Chicago, IL, USA) under local anesthesia when required, over two appointments 1 week apart. The individuals were provided oral hygiene instructions during each appointment. Analgesics were prescribed. None of the patients were prescribed antibiotics or anti-inflammatory drugs. All the parameters were recorded for this group after 1 month.
No participants were lost to follow-up. The data were expressed as mean and standard deviation (SD) and statistically analyzed. The normality of the distribution was assessed using the Kolmogorov–Smirnov/Shapiro–Wilk test. Based on this, the independent and dependent t-tests were applied for comparing the groups at baseline and after 1 month. The correlation of NLR and PLR with the other variables was estimated by the Karl Pearson's test. Receiver operating characteristics (ROC) was applied to estimate the cutoff point values for NLR and PLR. P value was set at ≤0.05. The IBM-SPSS (IBM-SPSS, Armonk, NY, USA) software was employed for the analyses.
| Results|| |
The age in years of Group H (n = 30) was 39.6 ± 0.96 (mean ± SD) and the CP group (n = 30) was 45.08 ± 3.62 with each group comprising 15 female and 15 male participants. [Table 1] depicts the mean ± SD of all the variables of the healthy group.
The clinical parameters and hematological variables of CP-BL when compared with CP-PT are depicted in [Table 2] and [Table 3].
|Table 2: Comparison of baseline and posttreatment clinical parameters in chronic periodontitis groups at baseline and posttreatment by dependent t-test|
Click here to view
|Table 3: Comparison of baseline and posttreatment platelets', lymphocytes', and neutrophils' counts in chronic periodontitis group by dependent t-test|
Click here to view
NLR showed statistically significant correlations with PLT (negatively in health, positively in CP-BL, CP-PT), with lymphocytes (negatively in health) and neutrophils (positively in health, CP-BL, CP-PT); whereas PLR showed statistically significant correlations with PLT (positively in health, CP-BL, CP-PT) and with lymphocytes (negatively in health). Although NLR in CP-BL correlated positively with PlI, PPD, and CAL (except GI), in CP-PT correlated negatively with GI, PPD, and CAL (except PlI); PLR in CP-BL correlated positively with PlI, GI, and PPD (except CAL), in CP-PT correlated negatively with PlI, PPD, and CAL (except GI), these were not statistically significant [Supplementary Table 4], [Supplementary Table 5], [Supplementary Table 6], [Supplementary Table 7].
The significant cutoff point by ROC for CP-BL versus CP-PT [Supplementary Figure 1] for NLR was 1.546 (sensitivity = 0.756, specificity = 0.756, area under curve = 77.5%) and PLR was 80.205 (sensitivity = 0.867, specificity = 0.622, area under curve = 80.6%).
| Discussion|| |
It is known that changes in peripheral blood parameters are useful in disease prognosis of many diseases. NLR and PLR are believed to be reliable markers of the inflammatory response. This investigation was an attempt to study the association of NLR and PLR in CP. The NLR and PLR can provide a reflection of the initial innate immune mechanisms (involving cells such as the neutrophils and macrophages providing a nonspecific response) which trigger the adaptive immune mechanisms (T-cell/B-cell mediated and stimulated in part by PLT) resulting in periodontal destruction. If NLR and PLR is higher, the inflammatory response will be more severe. A study  involving periodontitis compared MPV/PLT, PLCRi, NLR, and PLR in dogs (which were healthy, with periodontal disease and with oropharyngeal tumors) and concluded no significant associations between these parameters and periodontitis. It will be difficult to draw comparisons with our study as there is hardly any available literature addressing NLR and PLR together as potential systemic biomarkers of CP in humans before and after SRP. Only one study by Torrungruang et al. examined NLR and PLR in CP and diabetes in humans and reported an increased NLR with more severe periodontitis, but PLR decreased with more severe periodontitis and with worsening glycemic status. However, both these parameters have been assessed as systemic inflammatory indices in other diseases such as Mediterranean fever More Details, prosthetic valve thrombosis, and especially, carcinomas.,,,
The average NLR in healthy Caucasians controls has been shown to be 2.15 which is higher when compared with other races (for example, 1.76 in Non-Hispanic of African lineage), and to our sample of healthy controls which was Asian Indian, which means that NLR values may have a racial predilection. The average PLR in healthy controls has been reported to be approximately 103, lower compared with patients with cancerous lesions. Our study had lower PLR in health when compared with periodontitis, which means that PLR increases in a local inflammatory disease. It was interesting to note that NLR and PLR were lower in the CP-PT group as compared with the healthy group in the present evaluation, which may imply that there is a marked decrease due to therapeutic intervention. The ROC cutoff point values for NLR (1.546) and PLR (80.204) indicate that these measurements may be useful as a prognostic marker of CP.
NLR and PLR are considered better markers of inflammation as they have been found to be more effective predictors than just absolute leukocyte and PLT counts., Reports suggest that SIR is associated with neutrophilia and relative lymphocytopenia in systemic diseases., We did not note lymphocytopenia in our sample of systemically healthy CP patients. This may mean that CP and the additional presence of a systemic disease might better reflect SIR, as indicated by a study which analyzed only NLR and other mediators in CP and systemic diseases/conditions such as diabetes, hyperlipidemia, obesity, and menopause.
| Conclusion|| |
Within the limitations of this investigation, we suggest that NLR (the elevation of which may disrupt the balance between pro- and anti-inflammatory mediators in disease) and PLR (which is a marker of systemic inflammation) be included as potential parameters in studies exploring the oral-systemic axis to provide clarity to the impact CP may have on systemic health. NLR and PLR may be useful in stratifying CP patients and probably develop a grading or scoring system such as the Glasgow prognostic score (used in carcinomas) in conjunction with other inflammatory mediators to predict incidence and treatment outcomes.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Consensus report: Chronic periodontitis. Ann Periodontol 1999;4:38.
Van Dyke TE. Role of the neutrophil in oral disease: Receptor deficiency in leukocytes from patients with juvenile periodontitis. Rev Infect Dis 1985;7:419-25.
Seymour GJ, Powell RN, Davies WI. The immunopathogenesis of progressive chronic inflammatory periodontal disease. J Oral Pathol 1979;8:249-65.
Houri-Haddad Y, Wilensky A, Shapira L. T-cell phenotype as a risk factor for periodontal disease. Periodontol 2000 2007;45:67-75.
Croce K, Libby P. Intertwining of thrombosis and inflammation in atherosclerosis. Curr Opin Hematol 2007;14:55-61.
Nicu EA, Van der Velden U, Nieuwland R, Everts V, Loos BG. Elevated platelet and leukocyte response to oral bacteria in periodontitis. J Thromb Haemost 2009;7:162-70.
D'Aiuto F, Parkar M, Andreou G, Suvan J, Brett PM, Ready D, et al.
Periodontitis and systemic inflammation: Control of the local infection is associated with a reduction in serum inflammatory markers. J Dent Res 2004;83:156-60.
Christan C, Dietrich T, Hägewald S, Kage A, Bernimoulin JP. White blood cell count in generalized aggressive periodontitis after non-surgical therapy. J Clin Periodontol 2002;29:201-6.
Pejcić A, Kesić L, Pesić Z, Mirković D, Stojanović M. White blood cell count in different stages of chronic periodontitis. Acta Clin Croat 2011;50:159-67.
Loos BG. Systemic markers of inflammation in periodontitis. J Periodontol 2005;76:2106-15.
Shi D, Meng H, Xu L, Zhang L, Chen Z, Feng X, et al.
Systemic inflammation markers in patients with aggressive periodontitis: A pilot study. J Periodontol 2008;79:2340-6.
Gaddale R, Mudda JA, Karthikeyan I, Desai SR, Shinde H, Deshpande P. Changes in cellular and molecular components of peripheral blood in patients with generalized aggressive periodontitis. J Investig Clin Dent 2016;7:59-64.
López R, Loos BG, Baelum V. Hematological features in adolescents with periodontitis. Clin Oral Investig 2012;16:1209-16.
Thomas MR, Storey RF. The role of platelets in inflammation. Thromb Haemost 2015;114:449-58.
Ates S, Oksuz H, Dogu B, Bozkus F, Ucmak H, Yanıt F. Can mean platelet volume and mean platelet volume/platelet count ratio be used as a diagnostic marker for sepsis and systemic inflammatory response syndrome? Saudi Med J 2015;36:1186-90.
Liu Z, Li X, Zhang M, Huang X, Bai J, Pan Z, et al.
The role of mean platelet volume/platelet count ratio and neutrophil to lymphocyte ratio on the risk of febrile seizure. Sci Rep 2018;8:15123.
Batista TR, Figueiredo RC, Rios DR. Platelets volume indexes and cardiovascular risk factors. Rev Assoc Med Bras (1992) 2018;64:554-9.
Azab B, Camacho-Rivera M, Taioli E. Average values and racial differences of neutrophil lymphocyte ratio among a nationally representative sample of united states subjects. PLoS One 2014;9:e112361.
Guthrie GJ, Charles KA, Roxburgh CS, Horgan PG, McMillan DC, Clarke SJ. The systemic inflammation-based neutrophil-lymphocyte ratio: Experience in patients with cancer. Crit Rev Oncol Hematol 2013;88:218-30.
Motomura T, Shirabe K, Mano Y, Muto J, Toshima T, Umemoto Y, et al.
Neutrophil-lymphocyte ratio reflects hepatocellular carcinoma recurrence after liver transplantation via inflammatory microenvironment. J Hepatol 2013;58:58-64.
Kantola T, Klintrup K, Väyrynen JP, Vornanen J, Bloigu R, Karhu T, et al.
Stage-dependent alterations of the serum cytokine pattern in colorectal carcinoma. Br J Cancer 2012;107:1729-36.
Budzianowski J, Pieszko K, Burchardt P, Rzeźniczak J, Hiczkiewicz J. The role of hematological indices in patients with acute coronary syndrome. Dis Markers 2017;2017:3041565.
Bhat T, Teli S, Rijal J, Bhat H, Raza M, Khoueiry G, et al.
Neutrophil to lymphocyte ratio and cardiovascular diseases: A review. Expert Rev Cardiovasc Ther 2013;11:55-9.
Wang Y, Fuentes HE, Attar BM, Jaiswal P, Demetria M. Evaluation of the prognostic value of neutrophil to lymphocyte ratio in patients with hypertriglyceridemia-induced acute pancreatitis. Pancreatology 2017;17:893-7.
Young CA, Murray LJ, Karakaya E, Thygesen HH, Sen M, Prestwich RJ. The prognostic role of the neutrophil-to-lymphocyte ratio in oropharyngeal carcinoma treated with chemoradiotherapy. Clin Med Insights Oncol 2014;8:81-6.
Bozan N, Kocak ÖF, Dinc ME, Demir CY, Turan M, Kiroglu AF. Mean platelet volume, red cell distribution width, and neutrophil-to-lymphocyte ratio before and after surgery in patients with carotid body tumors. J Craniofac Surg 2017;28:e649-53.
Kim HA, Jung JY, Suh CH. Usefulness of neutrophil-to-lymphocyte ratio as a biomarker for diagnosing infections in patients with systemic lupus erythematosus. Clin Rheumatol 2017;36:2479-85.
Wang Y, Attar BM, Fuentes HE, Jaiswal P, Tafur AJ. Evaluation of the prognostic value of platelet to lymphocyte ratio in patients with hepatocellular carcinoma. J Gastrointest Oncol 2017;8:1065-71.
Zheng CF, Liu WY, Zeng FF, Zheng MH, Shi HY, Zhou Y, et al.
Prognostic value of platelet-to-lymphocyte ratios among critically ill patients with acute kidney injury. Crit Care 2017;21:238.
Zheng J, Cai J, Li H, Zeng K, He L, Fu H, et al.
Neutrophil to lymphocyte ratio and platelet to lymphocyte ratio as prognostic predictors for hepatocellular carcinoma patients with various treatments: A meta-analysis and systematic review. Cell Physiol Biochem 2017;44:967-81.
Tang K, Liu H, Jiang K, Ye T, Yan L, Liu P, et al.
Predictive value of preoperative inflammatory response biomarkers for metabolic syndrome and post-PCNL systemic inflammatory response syndrome in patients with nephrolithiasis. Oncotarget 2017;8:85612-27.
Park YM, Oh KH, Cho JG, Baek SK, Kwon SY, Jung KY, et al.
A prognostic scoring system using inflammatory response biomarkers in oral cavity squamous cell carcinoma patients who underwent surgery-based treatment. Acta Otolaryngol 2018;138:422-7.
Acharya S, Rai P, Hallikeri K, Anehosur V, Kale J. Preoperative platelet lymphocyte ratio is superior to neutrophil lymphocyte ratio to be used as predictive marker for lymph node metastasis in oral squamous cell carcinoma. J Investig Clin Dent 2017;8:e12219.
Silness J, Loe H. Periodontal disease in pregnancy. II. correlation between oral hygiene and periodontal condtion. Acta Odontol Scand 1964;22:121-35.
Loe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Scand 1963;21:533-51.
Song X, Chen D, Yuan M, Wang H, Wang Z. Total lymphocyte count, neutrophil-lymphocyte ratio, and platelet-lymphocyte ratio as prognostic factors in advanced non-small cell lung cancer with chemoradiotherapy. Cancer Manag Res 2018;10:6677-83.
Rejec A, Butinar J, Gawor J, Petelin M. Evaluation of complete blood count indices (NLR, PLR, MPV/PLT, and PLCRi) in healthy dogs, dogs with periodontitis, and dogs with oropharyngeal tumors as potential biomarkers of systemic inflammatory response. J Vet Dent 2017;34:231-40.
Torrungruang K, Ongphiphadhanakul B, Jitpakdeebordin S, Sarujikumjornwatana S. Mediation analysis of systemic inflammation on the association between periodontitis and glycaemic status. J Clin Periodontol 2018;45:548-56.
Uslu AU, Deveci K, Korkmaz S, Aydin B, Senel S, Sancakdar E, et al.
Is neutrophil/lymphocyte ratio associated with subclinical inflammation and amyloidosis in patients with familial Mediterranean fever? Biomed Res Int 2013;2013:185317.
Gürsoy OM, Karakoyun S, Kalçik M, Gökdeniz T, Yesin M, Gündüz S, et al.
Usefulness of novel hematologic inflammatory parameters to predict prosthetic mitral valve thrombosis. Am J Cardiol 2014;113:860-4.
Ertas IE, Gungorduk K, Akman L, Ozdemir A, Terek MC, Ozsaran A, et al.
Can preoperative neutrophil: Lymphocyte and platelet: Lymphocyte ratios be used as predictive markers for lymph node metastasis in squamous cell carcinoma of the vulva? Eur J Obstet Gynecol Reprod Biol 2013;171:138-42.
Pinato DJ, Stavraka C, Flynn MJ, Forster MD, O'Cathail SM, Seckl MJ, et al.
An inflammation based score can optimize the selection of patients with advanced cancer considered for early phase clinical trials. PLoS One 2014;9:e83279.
Acmaz G, Aksoy H, Unal D, Ozyurt S, Cingillioglu B, Aksoy U, et al.
Are neutrophil/lymphocyte and platelet/lymphocyte ratios associated with endometrial precancerous and cancerous lesions in patients with abnormal uterine bleeding? Asian Pac J Cancer Prev 2014;15:1689-92.
Horne BD, Anderson JL, John JM, Weaver A, Bair TL, Jensen KR, et al.
Which white blood cell subtypes predict increased cardiovascular risk? J Am Coll Cardiol 2005;45:1638-43.
Gabay C, Kushner I. Acute-phase proteins and other systemic responses to inflammation. N Engl J Med 1999;340:448-54.
Zahorec R. Ratio of neutrophil to lymphocyte counts – Rapid and simple parameter of systemic inflammation and stress in critically ill. Bratisl Lek Listy 2001;102:5-14.
Doǧan B, Fentoǧlu Ö, Kırzıoǧlu FY, Kemer ES, Köroǧlu BK, Aksu O, et al.
Lipoxin A4 and neutrophil/Lymphocyte ratio: A possible indicator in achieved systemic risk factors for periodontitis. Med Sci Monit 2015;21:2485-93.
[Table 1], [Table 2], [Table 3]