Cavcic 2000.

Methods	Quasi‐randomised study. Duration of study: 1990 to 2000 Follow‐up: 12 months
Participants	60 people with chronic radiation proctopathy and cytologically proven prostatic carcinoma staged to the TNM classification as T2N0M0 stage Sex (M/F): not reported Comparable groups with respect to age and previous treatment time Dropouts (after 3 months) IG: 3 CG: 12. Reasons for dropouts not explained
Interventions	Intervention: metronidazole (3 x 400 mg orally per day), mesalazine (3 x 1 g orally per day), and betamethasone enema (once a day) Comparator: same doses of mesalazine and betamethasone enema, but without metronidazole
Outcomes	The efficacy of metronidazole was assessed using rectal bleeding, diarrhoea, and endoscopy
Notes	The incidence of diarrhoea, rectal bleeding, ulcers and oedema was significantly reduced in the metronidazole group up to 12 months after treatment. No QoL
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Participants were allocated to 2 groups according to the date on which their treatment began (quasi random)
Allocation concealment (selection bias)	High risk	Allocation concealment could be foreseen, as participants were allocated according to the date on which their treatment began
Blinding (performance bias and detection bias)	High risk	Participants in intervention group received their medication orally, it seemed the intervention had not been blinded
Blinding of outcome assessment subjective	High risk	Participants in intervention group received their medication orally, it seemed the intervention had not been blinded
Blinding of outcome assessment objective	Low risk	Objective participant response was documented by rectal bleeding score and diarrhoea score. The participants were scored the same way before and after treatment. The same physician interviewed participants once a week during the treatment period, however unclear whether outcome assessment was blinded
Incomplete outcome data: subjective outcomes	High risk	Assessments before and after 4 weeks treatment: I: N = 30; C: N = 30. After 3 months dropouts: I: N = 3; C: = 12 (25%). After 1 year dropouts: I: N = 6; C: N = 18 (40%). After 2 years dropouts: I: N = 11; C: N = 20 (52%) Reasons for lost to follow‐up not reported. Not all participants were followed up for the same period of time: "The longest follow‐up period after 4 weeks treatment was 3 years, whereas the shortest one was 2 years."
Incomplete outcome data: objective outcomes	High risk	Assessments before and after 4 weeks treatment: I: N = 30; C: N = 30. After 3 months dropouts: I: N = 3; C: = 12 (25%). After 1 year dropouts: I: N = 6; C: N = 18 (40%). After 2 years dropouts: I: N = 11; C: N = 20 (52%) Reasons for lost to follow‐up not reported. Not all participants were followed up for the same period of time: "The longest follow‐up period after 4 weeks treatment was 3 years, whereas the shortest one was 2 years."
Selective reporting (reporting bias)	Unclear risk	No study protocol available, however all outcomes mentioned in the methods sections have been addressed in the results section
Other bias	Low risk	No indications of other bias