Data from all subjects in the present retrospective review were collected from the clinical database of The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University, between December 2010 and June 2013. This study was approved by the Institutional Ethics Committee of The Fifth People's Hospital of Wuxi, Affiliated to Jiangnan University (QD-2013-0016), and was in compliance with the national legislation and the Declaration of Helsinki guidelines. Written patient consent was obtained according to the institutional guidelines.

Healthy donors were from the physical examination center of our hospital and met the following criteria: no history of previous active TB or TB treatment, no evidence of current active TB (absence of cough, intermittent fever, and excessive night sweating in the past two weeks and absence of unexplained weight loss in the past month). Tuberculosis was diagnosed when subjects with clinical and/or imaging features compatible with tuberculosis had at least one of the following criteria: positive sputum smear for acid-fast bacilli (AFB); positive culture for M. tuberculosis; biopsy suggestive of tuberculosis, and/or full response to anti-tuberculosis treatment. Patients with extrapulmonary TB accompanying pulmonary TB involvement were included in the category of extrapulmonary TB. Treatment of new cases, both pulmonary and extrapulmonary tuberculosis, received two months of isoniazid (H), rifampicin (R), pyrazinamide (Z) and ethambutol (E) during an intensive phase and four months of HR in the continuation phase. The duration of treatment was six months. Several kinds of extrapulmonary tuberculosis were more difficult to cure. Treatment for an extended period of time was required to ensure disease control. Such as, prolonged therapy had been adopted in TB meningitis (9–12 months) and bone and joint TB (9 months; Fig. 1).9

Fig. 1.

Patient selection criteria used in this study.

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Full blood counts (FBC) of peripheral blood collected in ethylene-diamine tetra-acetic acid containing (EDTA) tubes were performed by one of two clinical diagnostic laboratories each using a five-part differential hematology analyser (Sysmex Model XS, Hamburg, Germany). Full blood count measurement was subject to strict quality assurance procedures including twice-daily high and low internal quality control, fortnightly quality controls done by the Wuxi clinical laboratory QC scheme (Wuxi, Jiangsu, China) and annual quality assurance as part of Jiangsu clinical laboratory QC scheme. Both laboratories are accredited by the China National Accreditation System in accordance with international standards ISO 17025/2005 and ISO 15189/2007.

Statistical analysis was conducted using SPSS version 17.0. Pearson's chi-square test and Mann–Whitney U test were used to identify significant differences across patients and healthy donors, patients before treatment and after treatment. p<0.05 (two-sided) was considered as statistically significant difference. The odds ratios (OR) were estimated with 95% confidence intervals (CIs) from the univariate analysis to investigate the relationship between active tuberculosis and the different ML ratios. Adjusted odds ratios (AOR) with 95% CIs were also estimated from the multivariate analysis to determine the factors associated with the different ML ratios of patients.

A total of 1068 patients were diagnosed with active TB in the database of The Fifth People's Hospital of Wuxi from December 2010 to June 2013. Availability of full differential blood counts when newly diagnosed with active TB (previously untreated for TB and never received anti-TB drugs for <1 month) was required to compare with healthy donors. Patients without pre-treatment data were excluded and 965 patients remained. We further excluded return-visiting patients, who experienced treatment failure or reinfection during the course of therapy, 638 patients remained. After excluding patients with viral hepatitis (viral hepatitis type A, B and C), AIDS (acquired immune deficiency syndrome), and diabetes, 464 patients remained. Individuals who were pregnant, did not agree to participate in our study, or had other diseases, such as, lung cancer, measles, syphilis, leucopenia, systemic lupus erythematosus, or rheumatoid arthritis, which were likely to influence full blood counts, were also excluded. Finally, data of full blood counts from 419 patients were included in the analysis, with a median age of 55 years, and 71.1% were men. Furthermore, in order to assess the influence of anti-TB therapy, we excluded patients who did not receive the recommended therapy, such as irregular treatment, intermittent treatment, and undertreated patients. Finally, 108 patients who had anti-TB therapy either near completion or completed remained. A total of 327 healthy volunteers were included, 207 male and 120 female subjects.

There were 746 individuals enrolled in the study: 419 patients with newly treated active tuberculosis, and 327 healthy donors without Mtb infection. Demographic and clinical characteristics and laboratory data are summarized in Table 1. There was no difference in median age or sex between patients and healthy donors. Patients with active tuberculosis had significantly higher median absolute number of white blood cell (WBC), monocytes and neutrophils than healthy donors. The median absolute number of lymphocytes of patients was significantly lower than that of healthy donors. Patients with active tuberculosis had a significantly different ML ratio to healthy donors.

Participants (patients and healthy donors) were stratified into categories of ML ratio of less than the 9th percentile, between the 9th and 25th percentile, and greater than the 25th percentile (Table 2). Compared to healthy donors, patients with active tuberculosis were distributed differently in the three categories: 73.9% of patients compared to 24% of healthy donors with ML ratio >the 25th percentile, 15.8% to 1.2% with ML ratiop<0.001) (Table 2). As shown in Fig. 2, ML ratio of healthy donors (blue circle) centralized mostly between the blue and green lines (91.4%); ML ratio of patients (green circle) distributed mainly out of the lines (89.7%) (Fig. 2A). ML ratio of healthy donors was the most centralized data (IQR 0.08), and gathered mainly in the area where the data from patients distributed rarely (Fig. 2B). Compared to ML ratio between the 9th and 25th percentile, participants with ML ratio the 25th percentile had a higher likelihood to be patients with active tuberculosis (OR =114.73, 95% CI, 39.80–330.71; OR=89.81, 95% CI, 53.18–151.68, respectively) (Table 2). It indicated that ML ratio less than the 9th percentile or greater than the 25th percentile were significant predictors for active tuberculosis.

Fig. 2.

Distribution of participants (patients and healthy donors) with ratio of monocytes to lymphocytes (ML ratio). (A) Monocytes and lymphocytes count are plotted on the x- and y-axes, respectively. ML ratio of healthy donors (blue circle) centralized mostly between the blue and green lines, ML ratio of patients (green circle) distributed mainly out of the lines. The dotted blue line denotes the 9th percentiles for ML ratio. The dotted green line denotes the 25th percentiles for ML ratios. (B) Median levels of ML ratio of patients of active tuberculosis and healthy donors. Each dot represents ML ratio for an individual patient or healthy donor. Bars represent medians. ML ratio of healthy donors gathered mainly in the area where the data from patients distributed rarely.

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A multivariate analysis was conducted using variables of gender, age and disease classification. As shown in Table 3, our study compared the characteristics of 334 from 419 patients who had clear information of disease classification. Male patients had a higher probability to be in the group of ML ratio <9% or ML ratio >25% than female patients, but the result had no statistical significance. Compared to patients less than 23 years of age, patients older than 60 years were over 4-fold more likely to be in the group of ML ratio <9% or ML ratio >25%. Patients with extrapulmonary tuberculosis were nearly 2.5-fold more likely to be in the extreme groups (Table 3).

In order to further evaluate the impact of anti-TB therapy on the ML ratio, we excluded patients who did not receive the recommended therapy, such as irregular treatment, intermittent treatment, and undertreated therapy. A total of 108 from 419 patients who had FBC with therapy either near completion or completed were remaining and was also stratified into the same three categories with ML ratio: less than the 9th percentile, between the 9th and 25th percentile, and greater than the 25th percentile. Anti-TB therapy significantly reduced ML ratio with ML ratio greater than 25th percentile (median ML ratio, 0.472 (IQR, 0.33–0.62) before treatment vs 0.2199 (IQR, 0.16–0.28) after treatment, p<0.001). ML ratio elevated significantly with ML ratio less than 9th percentile (median ML ratio, 0.026 (IQR, 0.006–0.059) before treatment vs 0.197 (IQR, 0.09–0.25) after treatment, p<0.001). In patients with ML ratio between the 9th and 25th percentile, there was no difference between ML ratio before treatment (median ML ratio, 0.20 [IQR 0.15–0.23]) and after treatment (median ML ratio, 0.15 [IQR, 0.12–0.19], p=0.166). Before anti-TB therapy, 9.3% of individuals (10/108) had ML ratio between the 9th and 25th percentile, compared with 75% (81/108) following anti-TB therapy (p<0.001). The median ML ratio of healthy donors was 0.15 (IQR, 0.12–0.19). The results indicated that higher ML ratio decreased, and lower ML ratio increased to be close to the ML ratio of healthy donors. ML ratio of patients recovered to be nearly normal with treatment.