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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