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Table 4 Methodological Assessment according to six domains of potential biases [QUIPS]27

From: Physical prognostic factors predicting outcome following lumbar discectomy surgery: systematic review and narrative synthesis

Study
[n = 6]
Study
Participation
Study Attrition
[Follow-up]
Prognostic
Factor
Outcome Confounding Factor Analysis Overall Risk of Bias
Divecha et al., 2014 High High Moderate Low Moderate Low High
Fischer et al., 2004 Moderate High Moderate Low Low Moderate High
Lewis et al., 1987 and Weir 1979 High High Moderate Low High High High
Nygaard et al., 2000 High High Moderate Low High High High
Silverplats et al., 2010 and Silverplats et al., 2011 Moderate Moderate Low Low Low Low Low
Solberg et al., 2005 Moderate High Low Low High Moderate High
  1. A study was considered to be of low risk of bias when all domains were rated as low-moderate risk of bias
  2. A study was considered to be of high risk of bias when ≥1 domain[s] were rated as high risk of bias