Quality assessment

The quality of all included studies was assessed by the first author (EA) and 25% of the included studies were assessed by the second author (PS). Cohen’s Kappa (k) inter-rater reliability measure²⁸ was calculated. The Joanna Briggs Institute (JBI) critical appraisal questionnaires were used to implement the GRADE approach²⁹ of quality assessment of the included studies. The GRADE approach is proposed by the Cochrane Collaboration³⁰ and it favours the JBI critical appraisal tools.³¹

The final quality scores per paper (table 2) were assigned based on five factors: risk of bias,³² inconsistency,³³ indirectness,³⁴ imprecision³⁵ and publication bias.³⁶ All the studies were graded based on their study type, for example, randomised controlled trials (RCTs) and systematic literature reviews were stated as high quality studies. Using the GRADE categories, we started from the highest possible score based on the study type, using the JBI questions to extract data per paper for the GRADE scoring, reducing the quality for each instance of the factors mentioned above.

Included primary studies characteristics

CBP, chronic back pain; LTRs, lung transplant recipients; MS, multiple sclerosis; PD, Parkinson’s disease; PDA, personal digital assistant; RCT, randomised controlled trial.