Excess mortality and tuberculosis among individuals with prolonged cough: a population-based study from Vietnam.
METHODS
A demographic surveillance site in north-west Vietnam.


OBJECTIVE
To compare notification rates of sputum smear-positive tuberculosis (TB) and mortality rates between the general population and individuals with prolonged cough.


METHODS
A cohort study of 559 prolonged cough cases in a total population of 35,832, observed over 2.5 years. Outcome measures were sputum smear-positive TB and death.


RESULTS
The age-standardised smear-positive TB notification rate among cough cases (553/100,000 person-years [py], 95%CI 268-1143) was significantly higher than in the general population (50/100,000 py, 95%CI 43-57), with a relative risk of 11.06 (95%CI 8.28-14.77). Among those who had a chest X-ray suggestive of TB but negative sputum smears prior to the study start, the rate was 6542/100,000 py (95%CI 2906-12,511). The cough cohort had a 2.61 (95%CI 2.38-2.87) times higher risk of dying than the general population.


CONCLUSIONS
Individuals with prolonged cough in this study run a significantly increased risk of developing infectious TB and of dying. We recommend further evaluations of improved follow-up systems aimed at identifying and treating sputum smear-negative TB cases before they convert to an infectious stage.
Hoa
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Department of Public Health Sciences, Division of International Health (IHCAR), Karolinska Institutet, Stockholm, Sweden.
Thorson
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D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003371:Cough / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D017678:Sex Distribution; D012959:Socioeconomic Factors; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000453:epidemiology / Q000401:mortality*; D014744:Vietnam / Q000453:epidemiology