|INTER & INTRA-READER VARIATIONS IN DIRECT MICROSCOPY
AND THEIR INFLUENCE ON SENSITIVITY & SPECIFICITY
|K Padmanabha Rao: Proceed 24th Natl TB & Chest
Dis Workers Conf, Trivandrum, 1969, 99-110.
A study was done to evaluate inter and intrareader
differences in reading of smears stained by Fluorescent Method (FM)
and Modified ZN Staining (CS) methods and variation in multiple
smears made from the same specimens in order to find out to what
extent sensitivity and specificity are influenced by repeated sputum
smears from same specimens, by change of readers or by repeated
Eighty sputum specimens with known results, 35
negative and 45 positive with different grades were selected. Ten
smears were prepared from each specimen. All the smears were first
examined by FM and later by CS method. Culture was also done for
these specimens. The findings were: (i) FM was more sensitive
than CS method. The specificity appeared to be equal in both.
(ii) Change of readers influenced the relative sensitivity of both
methods, but repeated examination by the same reader had no effect.
(iii) Both reader as well as reading influenced the specificity
of FM method but not that of CS method. (iv) Repeated sampling from
the same specimen had no effect on the sensitivity of both the methods,
while it had some effect on the specificity of FM method. (v) Consistency
among readers and readings was found to be poor in smears with low
grade positivity. (vi) The relative sensitivity of any method was
influenced by the proportion of low grade positive cultures in the
total pool. (vii) Examination of multiple smears from the same specimen
by more than one reader and more than one reading by the same reader
was more rewarding in CS method.
|KEY WORDS: SPUTUM EXAMINATION, SENSITIVITY,
SPECIFICITY, MODIFIED ZIEHL1-NEELSEN, FLUORESCENT.