| Background:Sputum culture plays an important role in monitoring treatment response in multidrug-resistant tuberculosis(MDR-TB)patients and sputum culture conversion is a clinical tool used to predict therapeutic efficacy during the follow-up.Regular monitoring of sputum cultures is critical for early detection of failed MDR TB patients.Although sputum culture conversion has been used substantially in clinical settings,few prospective cohort studies,none in China,have investigated the relationship between treatment outcomes of MDR-TB patients and sputum culture conversion.In addition,few prospective cohort studies have investigated its efficacy at different months of MDR-TB treatment and no studies have been performed in China and India.In addition,there are few studies researching the factors affecting the sputum culture conversion of MDR-TB patients.So far,there was no similar study in China.Methods:The study was conducted in four cities(Xuzhou,Lianyungang,Zhenjiang,and Nantong)in Jiangsu province,China.All MDR-TB patients were consecutively enrolled between 2011-2014.MDR-TB patients were identified at the time of diagnosis by regional laboratories using traditional drug sensitivity tests(DST),as previously described.Patients who tested sputum culture negative at baseline were excluded.Every patient signed an informed consent form,after which a questionnaire designed by local investigators was administered to gather important demographic and clinical information.MDR-TB patients accepted the standardization regimens or individual regimen,and the sputum culture test was carried out regularly.During the injection period,it was donel times a month,and during the non-injection period it was done 1 times every two months.Rates of sputum culture conversion were calculated and Cox proportional-hazards model was performed to evaluate the predictability of different months' culture conversion with treatment success in MDR-TB patients and analyse secondary factors that influenced sputum culture conversion in the process of MDR-TB treatment.Results:In all,139 MDR-TB patients with treatment outcomes were enrolled.Among those,106(76.3%)had converted their sputum,and the median conversion time was 91.5(IQR:34.0-111.8)days,which was much shorter(?2=26.05,P<0.001)than for the patients with treatment failure or death(174 days,95%CI 0-513).No statistically significant differences were found between culture conversion at 2 months and treatment success(HR=2.0;95%CI=0.9-4.5;P=0.087).However,patients who converted sputum culture at 3(HR=2.7;95%CI=1.3-5.5;P=0.007,6(HR=12.3;95%CI=5.0-30.3;P<0.001),and 24 months(HR=22.3;95%CI=7.2-69.4;P<0.001)had increased odds of treatment success compared to no converters.The overall sensitivity of sputum culture conversion at 2,3,6,and 24 months was 33.3%,52.4%,90.5%,and 95.2%,respectively.The specificity of these markers was 80.0%,70.9%,56.4%,and 52.7%,respectively.After multivariable analysis,smoking(HR=0.44;95%CI:0.23-0.83),drinking(HR=0.41;95%CI:0.21-0.81),ofloxacin resistance(HR=0.43;95%CI:0.24-0.76)and sputum smear grade>1(HR=0.51;95%CI:0.31-0.83)were less likely to have culture conversion.The median sputum culture conversion time of patients with successful treatment outcomes was 92.0 days(95%CI:85.5-98.5),much shorter(P<0.001)than amongst patients with treatment failure or death(174 days[95%CI:0-513]).Conclusions:In summary,our study suggests that sputum conversion at 6 months had a much higher sensitivity,but a substantially lower specificity,to predict MDR-TB treatment success compared with sputum conversion at 2 and 3 months.MDR-TB patients who smoke,drink,have ofloxacin resistance,or a high smear grade are less likely to respond to treatment and should be meticulously followed up. |
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