Skip to main content

Table 3 Primary study case example: effects of bariatric surgery on mortality in Swedish obese subjects

From: Observational evidence and strength of evidence domains: case examples

Strength of evidence factors Strength of evidence domains
Required domains Study limitations:
 • Reduced risk of selection bias: matched sample to address potentially influential confounding variables, minimal exclusion criteria, prospective study design, very large sample size
 • Reduced risk of detection bias: objective outcome and independent outcome assessors
 • Reduced risk of attrition bias: high rate of follow-up
 • Reduced risk of reporting bias: a priori protocol identifying primary outcomes
Directness: minimal exclusion criteria from a large sample at many hospitals and clinics provided direct evidence of key outcomes for the population of interest
Precision: adequately powered study resulted in a precise effect estimate