Table 1 Quality criteria of the randomized controlled trials assessed
From: EDTA chelation therapy for cardiovascular disease: a systematic review
Reference | Randomization | Sample size determination | Drop outs | Intention to treat analysis | Blinding | Allocation concealment |
|---|---|---|---|---|---|---|
Kitchell 1963 [17] | Not described (nor stated) | Not described | 33% of the treatment group upon cross-over | No | Allegedly participants blinded, but impossible to adequately assess | Unclear |
Olszewer 1990 [18] | Described | Not described | None | Yes | Initially double blinded but code was broken after 10 treatments and study was completed with single blind for remaining 10 treatments | Unclear |
Sloth-Nielsen 1991 [19] | Described | Not described | None | Yes | Double | Unclear |
Guldager 1992 [16] | Described | Not described | 4 drop outs by 3 months; 30 drop outs by 6 months | No | Double: code broken at 3 months | Unclear |
Guldager 1993 [15] | Not described | Not described | Not mentioned | No | Double | Unclear |
Van Rij 1994 [20] | Described | Yes | None | Yes | Double | Unclear |
Knudtson 2002 [4] | Described | Yes | 4 in placebo, 2 in treatment group | Yes | Double | Well described |