Dalakas 1997.

Methods	Double‐blind, placebo‐controlled, cross‐over study; 3 months' IVIg and 3 months of placebo, separated by a wash‐out period of at least 1 month
Participants	22 randomised (gender not specified) IVIg group mean age: 61.2 (42 to 74 years); mean disease duration 5.6 (3 to 10 years) Placebo group mean age: 66.1 (35 to 76 years); mean disease duration 7.4 (4 to 16 years) Inclusion criteria: diagnostic criteria of s‐IBM; active disease characterised by progressive muscle weakness; impaired ability to perform fully the activities of daily living; absence of another systemic illness Exclusion criteria: coronary artery disease; IgA deficiency; kidney dysfunction; bedridden patients
Interventions	3 months IVIg versus placebo with a wash‐out period of at least 1 month. The placebo consisted of dextrose in half normal saline, and IVIg dosage was 2 g/kg body weight. 3 participants also received concomitant treatment with prednisone
Outcomes	Change in manual muscle testing sum scores (deltoid; biceps brachii; triceps brachii; brachioradialis; wrist extensors; wrist flexors; iliopsoas; gluteus maximus; quadriceps femoris; hamstrings; neck, finger, and foot extension and flexion) graded using a modified (0 to 10) Medical Research Council (MRC) Scale. "The net differences in the MRC scores from baseline to the end of 3 months of treatment were compared between the patients randomized to the two treatment groups for each period. The cross‐over data were analyzed separately, comparing the baseline scores after the washout period to the end of the 3‐month treatment" Change in upper and lower limb MRC scores (limb‐by‐limb analysis) "from baseline to the end of the 3‐month treatment" Change in quantitative muscle testing sum scores from baseline at cross‐over to the end of the second period of treatment Participants’ assessment of their response to therapy at "the end of the study and prior to breaking the code" Swallowing function by ultrasound assessment of the duration of both wet and dry swallowing "measured at baseline, at the end of the first 3 months of treatment, and at the end of the second phase" 20‐item self assessment questionnaire on swallowing function, "measured at baseline, at the end of the first 3 months of treatment, and at the end of the second phase" Videofluoroscopy "62 individual items of oral motor examination using validated scales"
Funding	Not reported
Conflicts of interest	Not reported
Notes	"Patients were referred...for therapeutic studies during the period 1992‐1994"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random component in the sequence generation process described: "The patients were assigned to receive IVIg or placebo by a block‐randomization procedure"
Allocation concealment (selection bias)	Low risk	Central allocation described: "Randomization was performed at the pharmacy"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Insufficient information to permit judgement: "The principal investigator, the physicians, nurses, physical therapists, and statisticians were unaware of which treatment was administered" but "Sixteen of the 19 patients correctly identified the period during which they received placebo or IVIg"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement: blinding following allocation concealment not described fully
Incomplete outcome data (attrition bias) All outcomes	High risk	There were 3 dropouts after the first period of the trial (14% attrition); it was unclear whether 2 of the 3 dropouts received treatment or placebo
Selective reporting (reporting bias)	High risk	Outcomes for swallowing function incompletely reported (videofluoroscopy and self assessment questionnaire). No standard deviation values reported. No published protocol available
Other bias	High risk	Randomisation was broken by giving participants the option to cross over intervention. There was a minimum wash‐out period of 1 month, which may not be long enough to exclude a carry‐over effect. There was also a possible carry‐over effect from drug treatment taken prior to the trial

IgA: immunoglobulin A
 IVIg: intravenous immunoglobulin
 s‐IBM: sporadic inclusion body myositis