Gorlich 1991.
| Methods | Double‐blind, parallel group RCT, set in Germany | |
| Participants | 164 participants (mean age 56 years) suffering from at least 3 nights of leg cramps per week | |
| Interventions | Combination therapy of quinine sulphate plus theophylline ethylene diamine, or quinine alone, or placebo daily for 2 weeks. Before this treatment period, participants were put on placebo as a run‐in phase | |
| Outcomes | Cramp number, cramp nights, cramp intensity (graded 1 = mild to 3 = severe), cramp duration, adverse events | |
| Notes | Multicentre study in Germany conducted by Merrell Dow Pharma (now Sanofi‐Aventis) | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Quote: "für jedes Zentrum wurde eine Blockrandomisierung vorgenommen....."; [for each centre a blockwise randomization sequence was generated]......" Comment: probably adequate |
| Allocation concealment (selection bias) | Low risk | Quote: "Die Prüfärzte hatten für jeden Patienten einen verschlossenen Umschlag erhalten, in dem aussen die Randomnummer und innen das Prüfmedikament verzeichnet war" [Each prinicipal investigator was given a sealed envelope for each respective patient with the random number marked on the outside and the medication on the inside] Comment: probably done |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quote: " 3‐fache blinde Studienanlage" [Triple blind study setting]:; die äusserlich indentischen und nicht voneinander zu unterscheidenen Tabletten..." [from the outside identical tablets indistinguishable with respect to form, taste, colour...] Comment: participants, principal investigators and statistician were all blinded |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | "Tab.5: Gründe für die fehlende Aufnahme in die inferenzstatistischen Zeitreihenanalysen.." [Tab.5: Reasons for exclusion from statistical analysis] Comment: reasons are given for all participants not included in the statistical analysis |
| Selective reporting (reporting bias) | Low risk | Results of all outcome measures are reported |
| Other bias | Unclear risk | Conducted by manufacturer of quinine and also the quinine‐theophylline combination |