|ESTIMATION OF PREVALENCE OF BACILLARY TUBERCULOSIS
ON THE BASIS OF CHEST X-RAY AND/OR SYMPTOMATIC SCREENING
|GD Gothi, Radha Narayan, SS Nair, AK Chakraborty &
N Srikantaramu: Indian J Med Res 1976, 64, 1150-59.
The study was undertaken among 22,957 persons belonging
to 55 randomly selected villages of Nelamangala taluk of Bangalore
district in 1975, to find out precise estimates of prevalence of
bacillary disease. Symptom screening was done by well experienced
social investigators, according to a brief interview schedule. Sputum
was collected from all above the age of 5 years reporting chest
symptoms for seven or more number of days during the previous two
months. Within two weeks after symptom questioning, all were tuberculin
tested and all 5 years and above were X-rayed. Additional sputum
collection was done for those asymptomatics who had abnormal shadows
in their chest X-rays.
The overall prevalence rate of culture confirmed
bacillary cases by symptom and/or X-ray screening was 0.32 percent.
Same prevalence was seen with X-ray alone also. But the overall
prevalence rate based on symptom screening alone was 0.21 percent
which is significantly lower than that of symptom and/or X-ray screening,
or X-ray screening alone. The prevalence rates by age and sex based
on symptom screening were about two-thirds that of rate based on
X-ray and/or symptom screening. Hence to obtain prevalence rate
according to X-ray and/or symptom screening, a correction factor
of 1.52 should be applied to the prevalence rates obtained by symptom
screening alone. This correction factor is fairly good for most
of the age groups. It was also estimated that the cost of surveying
the population by symptom screening alone is about half that of
surveying the population by X-ray screening.
|KEY WORDS: PREVALENCE, CASE, SYMPTOM SCREENING,
X-RAY EXAMINATION, RURAL COMMUNITY.