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. 2020 Mar 4;10(3):e036248. doi: 10.1136/bmjopen-2019-036248

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
  1. Self-rated quality of life using the GSII (ranks 1, 2, 3)

  2. Self-rated depressive symptoms severity using the PHQ-9

  3. Self-rated WPAI questionnaire

  4. Use of prescribed hypnotics (quantified from 7 day diary)

  5. Use of other prescribed sleep-promoting medications (quantified from 7 day diary)

  6. Self-rated arousal and sleep effort using the PSAS and GSES

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.

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