Piai 1979.

Methods	RCT with cross‐over design
Participants	18 patients Unclear setting Diagnostic criteria not defined 56% females
Interventions	Spasmolytic prifinium 30 mg tds for 3 weeks
Outcomes	Global assessment, dichotomous
Notes	No run‐in
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind, methods not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	No drop‐outs
Selective reporting (reporting bias)	Low risk	All expected outcomes are reported
Other bias	Low risk	The study appears to be free of other sources of bias