title: Random blinded rechecking of AFB smears in a pilot project at an intermediate reference laboratory.
abstract: BACKGROUND
  In most developing countries, sputum smear microscopy for acid-fast bacilli remains the front line and often the only diagnostic tool for the diagnosis of tuberculosis (TB), making quality assurance of smear microscopy an important activity.
  
  
  OBJECTIVE
  To evaluate the results of a pilot study, where the random blinded rechecking for the entire state of Delhi was conducted at a reference laboratory.
  
  
  METHODS
  Slides from 25 Revised National Tuberculosis Control Programme designated districts (200 peripheral microscopy centres) in Delhi were re-read after proper coding by all the Senior Tuberculosis Laboratory Supervisors (STLS) at an intermediate reference laboratory under proper supervision.
  
  
  RESULTS
  Of 12,162 re-read slides, 204 discrepant results were found. Of these, 150 (73.5%) errors were attributed to the peripheral microscopy centres and 54 (26.5%) to STLS. High false-positive errors were observed at a frequency of 12/150 (8%), and high false-negative errors at a frequency of 38/150 (25%). Minor errors, i.e., low false-negative, low false-positive and quantification errors, were observed at frequencies of respectively 68/150 (45.3%), 17/150 (11.3%) and 15/150 (10.0%).
  
  
  CONCLUSIONS
  Greater stringency in the supervision of random blinded rechecking at the district level is essential to make smear rechecking more efficient and effective.
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: Z
authors.initials: Z
authors.lastname: Sidiq
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Hanif
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: K K
authors.initials: KK
authors.lastname: Chopra
authors.affiliation: State Tuberculosis Office, Delhi Government Dispensary, New Delhi, India.
authors.forename: A
authors.initials: A
authors.lastname: Khanna
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Ahmad
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: H
authors.initials: H
authors.lastname: Vashistha
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Saini
authors.affiliation: New Delhi Tuberculosis Centre, New Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Dubey
mesh_terms: D001431:Bacteriological Techniques / Q000592:standards*; D003906:Developing Countries; D003951:Diagnostic Errors / Q000517:prevention & control; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D007194:India; D059021:Laboratory Proficiency Testing; D008853:Microscopy / Q000592:standards*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D015588:Observer Variation; D010865:Pilot Projects; D011237:Predictive Value of Tests; D015397:Program Evaluation; D015203:Reproducibility of Results; D013183:Sputum / Q000382:microbiology; D013194:Staining and Labeling / Q000592:standards*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology