Table 1

Data extraction classification scheme

ClassificationDefinition
Reasons for early stopping
 (A) BenefitStopped because of benefit seen in the intervention group(s).
 (B) HarmStopped because of harm seen in the intervention group(s).
 (C) FutilityStopped because continuing the trial would be futile relative to establishing a treatment benefit.
 (E) FundingStopped because funding was for a specific timeframe or limited.
 (E) RecruitmentStopped because of lower than anticipated recruitment.
Reported adverse events
 (A) Severe harmsSerious adverse events, for example, death, hospitalisation, life-threatening outcome, disability or permanent damage.
 (B) Any harmDescribed non-specifically as ‘side effects’ or ‘any/total/overall adverse events’.
 (C) Organ system level harmsDescribed non-specifically as adverse events in the organ systems, for example, cardiovascular adverse events and gastrointestinal adverse events.
 (D) Specific harmsDescribed specifically, for example, nausea, headache and vomiting.
Reported harm-related endpoints
 (A) Discontinuations due to adverse eventsParticipants discontinued the trial due to adverse events.
 (B) Unexplained withdrawalsParticipants withdrew from the trial, but the reason is not reported or reportedly unknown (could be due to adverse events or lack of efficacy).
 (C) MortalityDeath from any cause (could be disease progression, adverse events or lack of efficacy).
Primary outcome category
 (A) BehaviouralFor example, attitudes and eating behaviours.
 (B) BiomarkerFor example, blood glucose and urine cultures.
 (C) PainFor example, pain relief and pain prevention.
 (D) PhysiologicalFor example, disease progression and mortality.
 (E) PsychologicalFor example, depression assessment scores and neuropsychological test.
 (F) Techniques/trainingFor example, method of intubation and effectiveness of a focus group.
 (G) Quality of lifeFor example, Short Form Health Survey (SF-36), patient satisfaction.
 (H) OtherAny outcome that does not fit in another category.