|SIGNIFICANCE OF PATIENTS WITH X-RAY EVIDENCE OF
ACTIVE TUBERCULOSIS NOT BACTERIOLOGICALLY CONFIRMED
|SS Nair: Indian J TB, 1974, 21, 3-5.
Available data from longitudinal study (1961-68)
from several different situations have been reviewed to understand
the significance of patients showing radiological evidence of pulmonary
tuberculosis without bacteriological confirmation. SITUATION IN
GENERAL POPULATION: Few of the smear negative but X-ray active tuberculous
patients (suspect cases) found in a survey of rural population done
by National TB Institute, were culture positive (7-10%). On follow
up for 18 months, only 3% of them became culture positive under
conditions where intervention with specific treatment was absent
or minimum. It is thus concluded that most of the cases diagnosed
as active tuberculosis on the basis of single X-ray are not likely
to be cases of tuberculosis. SITUATION AMONG SYMPTOMATICS ATTENDING
HEALTH INSTITUTIONS: Data from the State TB Demonstration and Training
Centres (STDTC) and the District Tuberculosis Programmes (DTP) have
been presented. The New Delhi Tuberculosis Centre records (1970)
show that only 27% of microscopy negative radiologically positive
patients were confirmed on culture. For Bangalore and Agra STDTC,
the proportions so confirmed were 20% and 25% respectively. It has
been calculated that in the DTPs, not more than 30% of the microscopy
negative radiologically positive patients could be the real cases
of tuberculosis. In the DTP situation not more than 10% of the suspect
cases may develop bacteriologically confirmed disease. Thus, not
many of the suspect cases could be real cases of tuberculosis either
on the basis of confirmation by culture or on the basis of development
of bacteriologically positive disease in future.
Are the cases diagnosed early by
radiology? The hypothesis that X-ray discovers cases in the
early stages has not yet been put to a scientific test. Further,
the large differences even between experienced readers in interpreting
X-ray shadows, render the method of X-ray diagnosis questionable.
Is anti tuberculosis treatment of suspect cases warranted?
The possible advantage of considering treatment of suspect cases
as chemoprophylaxis has to be weighed against conservation of resources
for treatment of infectious cases and the possible harmful effects
of anti TB drugs to persons who are not suffering from tuberculosis.
|KEY WORDS: CHEST SYMPTOMATICS, RURAL COIMMUNITY,
| PREVALENCE OF PULMONARY TUBERCULOSIS IN A PERI-URBAN
COMMUNITY OF BANGALORE UNDER VARIOUS METHODS OF POPULATION SCREENING
|AK Chakraborty, R Channabasavaiah, MS Krishna Murthy,
AN Shashidhara, VV Krishna Murthy & K Chaudhuri: Indian J TB
1994, 41, 17-27.
Screening of the population by Mass Miniature Radiography
(MMR) followed by sputum examination by culture of the X-ray abnormals
is the customary method for arriving at the prevalence rate of cases
in the community. It is not possible to use this methodology by
states to carry out prevalence surveys in these areas, even if they
desire to evaluate the effect of anti tuberculosis measures implemented
by them. Therefore, simpler means of screening population through
chest symptom for sputum examination has been studied by National
Tuberculosis Institute (NTI). The objectives of the present investigation
were to find out the prevalence of bacillary cases by screening
the population through identification of chest symptomatics by Social
Investigators (Sls) or General Health Workers (GHWs) compared to
that by MMR. In a peri urban area 10 kms away and around Bangalore
city all the villages were listed and of the 60 villages were selected
on the basis of a sample random sample. Of them, 30 were covered
by Sls of NTI and the other 30 by GHWs of the state government.
The methodology adopted was that (1) After census taking and registration
of the entire population aged 15 years and above, Sls questioned
the persons house to house for presence of cardinal chest symptoms
of any duration. All chest symptomatics were subjected to MMR and
sputum examination. (2) Similar methodology was adopted by GHWs
in the other 30 villages allotted to them. (3) Without knowing the
symptom status of all the registered persons, aged 15 years and
more belonging to all the 60 villages, were subjected to MMR and
from among those having X-ray abnormalities, to sputum examination.
It was found that GHWs had identified the same
proportion of the persons either having general symptoms or having
chest symptoms from the general population, as Sls. Prevalence rates
of culture positive as well as smear positive cases were similar
by any of the three methods i.e., 0.18%, 0.23% & 0.25% respectively.
Prevalence rates of smear positive cases obtained through symptom
questioning, either by Sls or GHWs, were more or less similar to
the estimates obtained by the more comprehensive screening method
of MMR and/or symptom questioning. The culture positive prevalence
rate following MMR screening was 0.25%, which was lower than the
rates observed in other surveys. The paper discusses the possible
hypothesis that could explain the observation. It also presents
correction factors to compute rates comparable to the best estimate
i.e., that obtained through comprehensive screening by MMR and/or
symptom questioning, followed by sputum culture.
|KEY WORDS: SCREENING TOOLS, CHEST SYMPTOMATICS,
MMR, PREVALENCE, CASE, PERI URBAN COMMUNITY.