The importance of quality control of sputum smear microscopy: the effect of reading errors on treatment decisions and outcomes.
METHODS
Ho Chi Minh City, Vietnam.


OBJECTIVE
To evaluate the impact of slide reading errors at peripheral level on case-finding and treatment decisions.


METHODS
Over a 6-month period in 1997, information on date, type of slide, results of other slides from the patient, and treatment status was collected for all slides from district TB centers detected as having reading errors during smear microscopy quality control re-readings.


RESULTS
Reading errors were detected in 117 slides: 115 (98.3%) were incorrectly read as negative, and 75 (65.2%) of these errors occurred in case-finding slides. In the 75 falsely negative case-finding slides, re-reading resulted in initiation of treatment in 38 patients (50.7%). The remaining 37 (49.3%) had only one positive slide and were told to return for follow-up after 6 months; the two (5.4%) who did return were both diagnosed with active TB. Detection of errors in the 40 false-negative follow-up slides resulted in treatment changes in four patients (10%).


CONCLUSIONS
Quality control plays a critical role in helping to ensure the timely diagnosis and treatment of new TB cases and appropriate management of patients currently on treatment. The usefulness of quality control could be enhanced by focusing greater efforts on case-finding slides initially read as negative.
Nguyen
T N
TN
Pham Ngoc Thach TB and Lung Disease Centre, Ho Chi Minh City, Vietnam.
Wells
C D
CD
Binkin
N J
NJ
Pham
D L
DL
Nguyen
V C
VC
D005069:Evaluation Studies as Topic; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy / Q000379:methods / Q000592:standards*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011379:Prognosis; D011786:Quality Control; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000628:therapy; D014744:Vietnam