Validation of candidate smear microscopy quality indicators, extracted from tuberculosis laboratory registers.
METHODS
Kinshasa Province, Democratic Republic of Congo.


OBJECTIVE
To identify and validate register-based indicators of acid-fast bacilli (AFB) microscopy quality.


METHODS
Selection of laboratories based on reliability and variation in routine smear rechecking results. Calculation of relative sensitivity (RS) compared to recheckers and its correlation coefficient (R) with candidate indicators based on a fully probabilistic analysis incorporating vague prior information using WinBUGS.


RESULTS
The proportion of positive follow-up smears correlated well (median R 0.81, 95% credibility interval [CI] 0.58-0.93), and the proportion of first smear-positive cases fairly (median R 0.70, 95% CI 0.38-0.89) with RS. The proportions of both positive suspect and low positive case smears showed poor correlations (median R 0.27 and -0.22, respectively, with ranges including zero).


CONCLUSIONS
The proportion of positives in follow-up smears is the most promising indicator of AFB smear sensitivity, while the proportion of positive suspects may be more indicative of accessibility and suspect selection. Both can be obtained from simple reports, and should be used for internal and external monitoring and as guidance for supervision. As proportion of low positive suspect smears and consistency within case series are more difficult to interpret, they should be used only on-site by laboratory professionals. All indicators require more research to define their optimal range in various settings.
Van Deun
A
A
Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium. avdeun@itg.be
Zwahlen
M
M
Bola
V
V
Lebeke
R
R
Bahati
E
E
Lubamba
P
P
Rieder
H L
HL
D015023:Democratic Republic of the Congo / Q000453:epidemiology; D006801:Humans; D008390:Markov Chains; D008853:Microscopy / Q000592:standards*; D019984:Quality Indicators, Health Care; D012042:Registries; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology