Laboratory and clinico-demographic profile of patients investigated for tuberculosis in the National Referral Hospital of Bhutan

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, is an important public health problem in Bhutan. Microscopy is the primary method of diagnosis of TB in developing countries including Bhutan. Performance of microscopy in the Jigme Dorji Wangchuck National Referral Hospital (JDWNRH), has never been assessed. A retrospective review of laboratory records for three years (2014–2016) was performed to determine the laboratory profile of patients investigated for different types of TB at the JDWNRH. A total of 10,821 sputum and 3,495 non-sputum samples were examined for pulmonary TB (PTB) and extrapulmonary TB (EPTB) respectively. The commonest EPTB samples were Fine Needle Aspiration Cytology (FNAC), urine and sterile fluids. About 6% (127/2163), 5 % (130/2390) and 5% (289/5310) were positive for PTB in 2014, 2015 and 2016 respectively and EPTB positivity was about 7% in all years. During follow-up a significant number of patients remained sputum positive. Sputum sample satisfactory rate (quality) varied between 51 % to 79% in the primary samples. Sample completeness (number) ranged between 62.3% to 94.6% but dropped sequentially in the follow-up cases. Sample completeness of urine samples for EPTB ranged between 75-90%. EPTB positivity rate was highest in FNAC, followed by urine, pleural fluid and ascitic fluid samples. Higher number of patients were investigated for TB in subsequent years from 2014 to 2016. TB positivity rates for PTB and EPTB remained consistent over three years at about 5–6% and 7% respectively. There was a significant variation in sputum sample adequateness (by quality and number). Sputum conversion in the follow-up cases was lower than other countries. Educating the patients on the importance of providing adequate samples can improve TB diagnosis, enhance early treatment, reduce transmission and contribute significantly towards TB elimination.