Table 2 Frequency of outcome reporting classifications for each reporting itemfor the primary outcome in 18 included RCTs

1. Described the outcome domain^b

N/A

2. Stated the outcome

N/A

3. Specified the outcome as primary

N/A

4. Provided a rationale for classifying the outcome as primary, instead of secondary

N/A

5. Defined clinical significance on the outcome (e.g., minimal important difference, responder definition), including what would constitute a good or poor outcome

N/A

6. Justified the criteria used for defining meaningful change (e.g., the minimal important difference, responder definition), including what would constitute a good or poor outcome, such as from an outcome measurement interpretation guideline

N/A

7. Explained how the outcome addresses/relates to the hypothesis of the study

N/A

8. Explained how the outcome addresses the objective/research question of the study (i.e., to compare the effect of intervention A versus intervention B on outcome X)

N/A

9. Described why the outcome is relevant to each stakeholder group involved in this trial (e.g., patients, decision makers, policy makers, clinicians, funders, etc.)

N/A

10. Reported which stakeholders (e.g., patients, decision makers, policy makers, clinicians, funders, etc.) were actively involved in outcome selection

N/A

11. Explained the mechanism (e.g., pathophysiological, pharmacological, etc.) or theoretical framework/model by which the experimental intervention is expected to cause change in the outcome in the target population

N/A

12. Provided rationale for the choice of the specific type of outcome (e.g.,., why a patient-reported outcome instead of a clinician reported outcome)

N/A

13. Described the outcome measurement instrument used. This should include instrument scaling and scoring details (e.g., range and direction of scores)^c

8 (44)

14. Specified whether the outcome measurement instrument will be used in accordance with any user manual and specify and justify deviations if planned

N/A

15. Specified a recall period for outcome measurement instrument

N/A

16. Described mode of outcome assessment (e.g., face to face, telephone, electronically)

N/A

17. Justified the mode of outcome assessment (e.g., justification for equivalence between different modes of administration, if applicable)

N/A

18. Described any additional resources/materials or processes when performing outcome assessment, when relevant (e.g.,, a stethoscope, language interpreter, fasting prior to colonoscopy, etc.)

N/A

19. Described or provided reference to an empirical study that established validity of the outcome measurement instrument in individuals similar to the study sample (i.e., measures what it is supposed to measure)^c

3 (19)

20. Described or provided reference to an empirical study that established validity of the outcome measurement instrument in the study setting (i.e., measures what it is supposed to measure)^c

3 (19)

21. Specified whether more than one language version of the outcome measurement instrument was used and state whether translated versions have been developed using currently recommended methods, if applicable

0 (0)

22. Described or provided reference to an empirical study that established reliability of the outcome measurement instrument in individuals similar to the study sample (i.e., ability to produce consistent results)^c

6 (33)

23. Described or provided reference to an empirical study that established reliability of the outcome measurement instrument in the study setting (i.e., ability to produce consistent results)^c

7 (39)

24. Described or provided reference to an empirical study that established the responsiveness of the outcome measurement instrument in the study sample (i.e., ability to detect change over time given a change in disease activity or status)

0 (0)

25. Described the feasibility of the outcome measurement instrument in the study sample (i.e., the practical considerations of using an instrument, including its ease of use, time to complete, monetary costs, and interpretability of the question(s) included in the instrument)

0 (0)

26. Described the acceptability and burden of the outcome measurement instrument in the study sample^c

1 (6)

27. Specified whether order of administration of outcome measurement instrument was standardized, if assessing multiple outcomes

N/A

28. Specified whether outcome data will be monitored during the study to inform the clinical care of individual trial participants, and if so, how this will be managed in a standardized way

0 (0)

29. Described who (e.g., nurse, occupational therapist, technician, parent, outcome adjudicators), and if applicable, how many, assessed the outcome in each study group

0 (0)

30. Justified the choice of outcome assessor(s) (e.g., proxy versus healthcare provider)

N/A

31. Described whether the outcome assessor(s) were blinded/masked to intervention assignment

N/A

32. Described any study-specific training required for outcome assessors to apply the outcome measurement instrument

N/A

33. Described how outcome data quality was maximized (e.g., duplicate measurements)

N/A

34. Specified geographic location of outcome assessment for each study group (e.g., list of countries where outcome data was collected)

N/A

35. Described setting of outcome assessment for each study group (e.g., clinic, home, other)

N/A

36. Justified suitability of the outcome assessment setting(s) for the study sample (e.g., family doctor office vs. home when measuring blood pressure)

N/A

37. Specified timing and frequency of outcome assessment(s) for outcomes (e.g., time point for each outcome, time schedule of assessments)^c

2 (11)

38. Provided justification of timing and frequency of outcome assessment(s) (such as pathophysiological or epidemiological evidence for disease processes and complications to occur and/or pragmatic justification)

0 (0)

39. Provided definition of outcome analysis population

N/A

40. Described unit of analysis of the outcome (i.e., cluster or individual)

N/A

41. Described outcome analysis metric (e.g., change from baseline, final value, time to event)

N/A

42. Described method of aggregation for outcome data (e.g., mean, median, proportion)

N/A

43. Described statistical methods and/or significance test(s) (name or type) used for analyzing outcome data. This should include any analyses undertaken to address multiplicity/type I (α) error, particularly for trials with multiple domains and time points^c

7 (39)

44. Described the covariates and factors in the statistical model (e.g., adjusted analyses) used for analyzing outcome data, if applicable

N/A

45. Provided justification for covariates and factors and why they were selected, if applicable

N/A

46. Described results for each group, including estimated effect size and its precision (such as 95% confidence interval). For binary outcomes, presentation of both absolute and relative effect sizes is recommended^c

4 (22)

47. Described time period (i.e., chronological time since randomization) for which the outcome was analyzed

N/A

48. Described outcome data, assessment process, and analysis for participants who discontinued or deviated from the assigned intervention protocol^c

15 (83)

49. Described outcome data entry, coding, security and storage, including any related processes to promote outcome data quality (e.g., double entry, range checks from outcome data values)

1 (6)

50. Described blinding procedure(s) applied to data entry personnel and/or data analysts

0 (0)

51. Described methods for additional analyses (e.g., subgroup analyses), if applicable

N/A

52. Described how much outcome data was missing

N/A

53. Described any reasons for missing outcome data in each arm (e.g.,, reasons for withdrawal or reasons for lack of follow-up), with enough detail that the reported reason can be used to reduce the uncertainty about the potential underlying mechanism of missing outcome data

0 (0)

54. Explained statistical methods to handle missing outcome items or entire assessments (e.g., multiple imputation)

N/A

55. Provided justification for methods used to handle missing outcome data. This should include: (1) assumptions underlying the missing outcome data mechanism with justification (including analyses performed to support assumptions about the missingness mechanism); and (2) how the assumed missingness mechanism and any relevant features of the outcome data would influence the choice of statistical method(s) to handle missing outcome data including sensitivity analyses^c

1 (6)

56. Described any outcome analyses conducted to assess the risk of bias posed by missing outcome data (e.g., comparison of baseline characteristics of participants with and without missing outcome data)

N/A

57. Interpreted outcome data in relation to clinical outcomes, where relevant

N/A

58. Discussed impact of missing outcome data on the interpretation of findings, if applicable

N/A