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Table 2 Tool for assessment of quality and bias

From: The burden of pertussis in low- and middle-income countries since the inception of the Expanded Programme on Immunization (EPI) in 1974: a systematic review protocol

Item Score
1. Study design (selection score)  
  a. Prospective clinical studies (any type)  
   ♦ Consecutive enrolment 2
   ♦ Unspecified/random enrolment 1
  b. Autopsy studies  
   ♦ Consecutive enrolment 2
   ♦ Unspecified/random enrolment 1
  c. Retrospective reviews (including subgroup analysis) 1
  d. Review/editorial 0
  e. Case report 0
2. Study objectives (selection score)  
  a. Clear inclusion criteria  
   ♦ Aim related to pertussis prevalence or outcomes 3
   ♦ Related to OIs/general morbidity/respiratory disease but not specific to pertussis 2
   ♦ Unrelated to clinical pertussis prevalence 1
  b. Unclear inclusion criteria 1
3. Diagnosis* (quality of outcome ascertainment)  
  a. Laboratory-confirmed (any specified method/specimen) 2
  b. Clinical case definition (consistent with WHO or CDC guidelines) 1
  c. Not specified 0
4. Denominator  
  a. Raw data denominator 2
  b. Calculated denominator 1
  c. No/unclear denominator/investigated < % of cohort for pertussis/exclusion group 0
5. Numerator (Pertussis numbers)  
  a. Raw data numerator 2
  b. Calculated numerator 1
  c. No/unclear numerator (clinical pertussis not mentioned/tested) 0
6. Assessment of bias (low, high or unclear risk)  
  a. Attrition bias  
   ♦ Amount, nature or handling of incomplete outcome data  
  b. Selection bias  
   ♦ Representativeness of the cases/cohort (clear reasons for and rates of non-inclusion)  
  1. *Do not include data from clinical episodes of pertussis if no case definition provided (even if study otherwise qualifies). CDC, Centers for Disease Control; OI, opportunistic infection; WHO, World Health Organisation.