Table 1.
Objectives and outcome measures
Objectives | Outcome measures | Timepoint(s) of evaluation of this outcome measure |
Primary objective: To compare the effect of SRT+SH vs SH on insomnia severity |
Self-rated insomnia severity using the ISI questionnaire | Baseline, 3, 6 and 12 months post-randomisation. Primary outcome is at 6 months. |
Secondary objectives: To compare the effect of SRT+SH vs SH on HRQoL |
Self-rated HRQoL using the SF-36 questionnaire (total score, MCS, PCS) | Baseline, 3, 6 and 12 months post-randomisation. |
To compare the effect of SRT+SH vs SH on subjective sleep | Subjective sleep recorded over 7 nights using the CSD (SOL; WASO; SE; TST; SQ) | Baseline, 6 and 12 months post-randomisation. |
To compare the effect of SRT+SH vs SH on objective estimates of sleep | Actigraphy-defined sleep over 7 nights (SOL; WASO; SE; TST) |
Baseline, 6 and 12 months post-randomisation. |
To compare the effect of SRT+SH vs SH on (1) patient-generated quality of life, (2) depressive symptoms, (3) work productivity, (4) hypnotic medication use, (5) use of other prescribed sleep-promoting medications and (6) pre-sleep arousal and sleep effort |
|
Baseline, 3, 6 and 12 months post-randomisation. Medication use will be quantified from diaries at baseline, 6 and 12 months post-randomisation. |
To compare the incremental cost-effectiveness of SRT+SH over SH, from both NHS and societal perspectives | Trial records (time and number of nurse-led appointments), practice records* (medications), CSRI, ISI, WPAI, EQ-5D-3L | Baseline, 3, 6 and 12 months post-randomisation. *Baseline and 12 months only |
To undertake a process evaluation to explain trial results and understand intervention delivery, fidelity and acceptability. | Semi-structured interviews with (1) trial participants, (2) nurses, (3) GPs or practice managers. | Throughout the trial. |
Moderator analysis: Test whether objective short sleep duration at baseline (<6 hours vs ≥6 hours) moderates the effect of SRT on clinical outcomes (at 6 months) |
Actigraphy, ISI, GSII, SF-36 | Baseline and 6 months. |
Mediator analysis: Test whether group difference on the ISI (6 months) is mediated by change in PSAS and GSES assessed at month 3 Test whether SRT adherence mediates degree of clinical change on the ISI |
ISI, PSAS, GSES Sleep diary during intervention phase, ISI |
Baseline, 3 and 6 months. |
To compare the number of specified adverse events between the groups | Questionnaire | Baseline, 3, 6 and 12 months. |
CSD, Consensus Sleep Diary; CSRI, client service receipt inventory; EQ-5D-3L, EuroQol 5 Dimensions 3 Levels Questionnaire; GPs, general practitioners; GSES, Glasgow Sleep Effort Scale; GSII, Glasgow Sleep Impact Index; HRQoL, health-related quality of life; ISI, Insomnia Severity Index; MCS, mental component summary score; NHS, National Health Service; PCS, physical component summary score; PHQ-9, patient health questionnaire; PSAS, Pre-Sleep Arousal Scale; SE, sleep efficiency; SF-36, Short Form 36 Questionnaire; SH, sleep hygiene; SOL, sleep-onset latency; SQ, sleep quality; SRT, sleep restriction therapy; TST, total sleep time; WASO, wake time after sleep onset; WPAI, work productivity and activity impairment questionnaire.