One article scored 5, and the remaining four scored 4 out of 6 because the papers did not specify whether the assessors were blind to the patient's treatment programme, and there was no clear action to minimise the systematic bias.
Only one article scored excellent on hypothesis testing of the correlation between the MHHS and SF-36 [ 20].
Similarly, authors described the 'magnitude' of treatment effect infrequently an average score of 3.4 was assigned to this item with 13 of 26 articles scoring a 5 for this item and 7 articles scoring a 1.
Similarly, most authors described the 'magnitude' of treatment effect only partially an average score of 3.5 was assigned to this item with 11 of 26 articles scoring a 5 for this item, 13 articles scoring a 3 for this item, and two articles scoring a 1.
The item 'opinions versus facts' averaged 4.2 with 16 of 26 articles scoring a 5 for this category.
Empirical articles achieving a minimum average score of 10 (of a possible 17) and non-empirical and grey articles scoring a minimum of 5 (of a possible 10; see Additional file 3 for quality rating sheets) were retained.
We considered scores between 15 and 17 points to be high quality, scores between 12.5 and 14.9 points to be medium quality, and articles scoring in the 10 12.4 point range to be a low quality of evidence.
In general, the description of the sample population was poor and none of the articles scored positively for item 1 due to the absence of a flow diagram describing the flow of patients in the selection process.
Most articles scored particularly low on blinding the assessor, the care provider, and the participant.
