Predicting the risk of pulmonary tuberculosis based on the neutrophil-to-lymphocyte ratio at TB screening in HIV-infected individuals

Reiko Miyahara,Prarit Prachamat,Hideki Yanai,Norio Yamada,Surachai Piyaworawong,Jiraporn Wongyai,Vivek Naranbhai,Prapimporn Kriengwatanapong,Surasit Bupachat,Surin Summanapan,Surakameth Mahasirimongkol,Naho Tsuchiya

doi:10.1186/s12879-019-4292-9

Abstract

BackgroundThe neutrophil to lymphocyte ratio (NL ratio) has been reported to be a predictive biomarker of tuberculosis (TB). We assessed the association between the NL ratio and the incidence of active TB cases within 1 year after TB screening among HIV-infected individuals in Thailand.MethodsA day care center that supports HIV-infected individuals in northernmost Thailand performed TB screening and follow-up visits. We compared the baseline characteristics between the TB screening positive group and the TB screening negative group. The threshold value of NL ratio was determined by cubic-spline curves and NL ratios were categorized as high or low NL ratio. We assessed the association between NL ratio and progression to active TB within 1-year using the Cox-proportional hazard model.ResultsOf the 1064 HIV-infected individuals who screened negative for TB at baseline, 5.6% (N = 60) eventually developed TB and 26 died after TB diagnosis. A high NL ratio was associated with a higher risk of TB (adjusted hazard ratio (aHR) 2.19, 95% CI: 1.23–3.90), after adjusting for age, sex, ethnicity, CD4 counts, and other risk factors. A high NL ratio in HIV-infected individuals with normal chest X-ray predicted TB development risk. In particular, a high NL ratio with TB symptoms could predict the highest risk of TB development (aHR 2.58, 95%CI: 1.07–6.23).ConclusionsOur results showed that high NL ratio increased the risk of TB. NL ratio combined with TB symptoms could increase the accuracy of TB screening among HIV-infected individuals.

Highlights

The neutrophil to lymphocyte ratio (NL ratio) has been reported to be a predictive biomarker of tuberculosis (TB)
Fifty-four patients diagnosed with active TB and who started TB medication were excluded from the subsequent analysis, based on the detection of at least 1 acid fast bacilli (AFB) positive smear (N = 8, 14.8%), TB culture positive (N = 40, 74.1%), or clinical symptoms highly suspected to be TB (N = 41, 75.9%)
Patients that were TST positive, had abnormal chest X-rays, or reported TB symptoms were strongly associated with active TB compared to patients who were TB screening negative (Table 1)

Summary

Introduction

The neutrophil to lymphocyte ratio (NL ratio) has been reported to be a predictive biomarker of tuberculosis (TB). We assessed the association between the NL ratio and the incidence of active TB cases within 1 year after TB screening among HIV-infected individuals in Thailand. Individuals infected with human immunodeficiency virus (HIV) have a significantly higher risk of TB morbidity and mortality rates relative to HIV-uninfected individuals [1]. Thailand has a high burden of TB and HIV-TB co-infection. In 2016, HIV-infected individuals comprised 4764 (8%) of 68,040 total new and relapse TB cases, and 3900 HIV-associated TB deaths were reported in that year [1]. A previous study reported that half of all deaths occurring within 2 months of commencing TB treatment occurred among HIV-TB co-infected individuals due to difficulty in and delayed TB diagnosis [2]. Detection of TB and preventive therapy is essential to reduce the morbidity and mortality from TB in HIV-infected individuals

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