Compliance with continuous positive airway pressure for obstructive sleep apnoea
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To determine the clinical effectiveness of interventions in improving compliance with CPAP in adults with OSA.
Background
Obstructive sleep apnoea may affect up to 4% of men and 2% of women and if left untreated is associated with significant morbidity and mortality (Young 1993; Partinen 1998). CPAP has become the treatment of choice for OSA. It has been shown to improve ventilatory function (Berthen‐Jones 1987), objective and subjective measures of daytime somnolence (Engleman 1998), and quality of life (Jenkinson 1999) in patients with moderate to severe OSA.
The success of CPAP is probably dependent on regular use. The number of hours of use required to achieve clinical effectiveness is unknown, 6‐8 hours each night is the usual prescription. Concern about the acceptance and compliance with CPAP has been raised. Long term adherence to CPAP therapy was initially reported to range from 65‐80% (Nino Murcia 1989; Waldhorn 1990; Rolfe 1991; Hoffstein 1992) with 8‐15% of patients refusing to accept treatment (Waldhorn 1990; Krieger 1992) after a single night's use. Other studies have evaluated compliance as regular CPAP use. Only 46% of patients fell into the category of regular users (defined as at least 4 hours of CPAP per day and more than 70% of the days CPAP was to be administered) (Kribbs 1993). More recent studies have shown up to 80% of patients falling into the category of regular users (Pepin 1999).
Several factors may influence compliance with CPAP therapy (Pepin 1999) . Among these are motivation linked to severity of symptoms and satisfaction with the mode of therapy, discomfort including claustrophobia and upper airways side effects from the use of CPAP and the degree of education about OSA, and its treatment.
Various methods to improve compliance have been proposed; one, enhanced patient education and support, two, humidification therapy to reduce side effects of upper airway symptoms and three, use of auto CPAP which aims to reduce mean mask pressure which decreases the haemodynamic and local side effects of CPAP therapy.
This review aims to examine the impact of these methods on compliance with CPAP for OSA.
Objectives
To determine the clinical effectiveness of interventions in improving compliance with CPAP in adults with OSA.
Methods
Criteria for considering studies for this review
Types of studies
Studies will be randomized and controlled, either parallel group or crossover design and may be single blind. Studies of any duration will be considered.
Types of participants
Participants will be adults of either sex with a diagnosis of OSA, based on history and results of sleep studies. The sleep studies will be either oximetry studies showing desaturation index (DI) of at least 5 per hour or of respiratory movements and airflow to give an apnoea hypopnoea index (AHI) of at least 5 per hour.
Types of interventions
Participants will be randomized to receive one, intensive education and/or support vs. standard education and/or support, two, humidification vs. no humidification and three, auto CPAP vs conventional CPAP.
Types of outcome measures
The following outcomes will be to be examined where available
1) Hours of use measured
*Subjectively from patients' reports of the duration of CPAP use
*Objectively from either :
a) Counter output that records the cumulative time that power is turned on to a CPAP machine (this does not provide information on actual time of day and duration of CPAP used each 24 hour period).
b) Microprocessor and monitor that measures the pressure at the mask for every minute of each 24 hour day.
2) Desaturation index, apnoea hypopnoea index, respiratory disturbance index, and minimum arterial saturation during sleep.
3) Symptom scores such as the Epworth Sleepiness Scale, Stanford Sleepiness Score and Nasal symptoms.
4) Quality of life or Health Status such as the Short Form 36, Nottingham Health Profile.
Search methods for identification of studies
Searches will be carried out on the Cochrane Airways Group RCT Register derived from a search of EMBASE, MEDLINE, and CINAHL. Additional hand searching will be performed as relevant.
Searches will be made using the terms:
*Sleep apnoea (or sleep apnea)
*Compliance
*Patient education
*Humidification therapy
*Auto CPAP
An advance search of CENTRAL the Cochrane controlled trials registrar will be completed using the above search strategy.
Authors of studies will be contacted to locate other unpublished or in progress studies which meet the inclusion criteria. Bibliographies from included studies, reviews and texts will be searched for citations.
Data collection and analysis
Initially the titles, abstracts and citations will be independently reviewed by the two reviewers to assess potential relevance for full review.
Subsequently, from the full text, both reviewers independently will asses the studies for inclusion based on the criteria for population, intervention, study design and outcomes. Agreement will be measured by simple agreement and kappa statistics. Disagreement will be resolved by a third party.
SELECTION OF STUDIES
Both reviewers, using two methods, subjected studies included to quality assessment. First, using the Cochrane approach to assessment of allocation concealment, trial will be scored and entered using the following principles:
Grade A: Adequate concealment
Grade B: Unclear concealment
Grade C: Obviously not adequate concealment
Each study will be assessed for validity on a 0‐5 scale, method of Jadad (1996) as follows:
1. Was the study described as randomised? (1=yes, 0=no)
2. Was the study described as double blind? (1=yes, 0=no)
3. Was there a description of withdrawals and dropouts? (1=yes, 0=no)
4. Was the method of randomization well described and appropriate? (1=yes, 0=no)
5. Was the method of double blinding well described and appropriate? (1=yes, 0=no)
6. Deduct 1 point if methods of randomization or blinding were inappropriate.
Inter‐rater reliability will be measured using simple agreement.
DATA EXTRACTION
Data will be extracted from published selected studies independently by MH and IES and entered into the Cochrane Collaboration software program, Review Manager. Data in table or graphic form will be to be used if published and authors will be requested to confirm data extraction and provide clarification and additional information for the review.
STATISTICAL CONSIDERATIONS
All included trials will be to be combined using the Review Manager MetaView software package.
For continuous variables the results of individual studies will be calculated as fixed effects weighted mean difference (WMD) or standardized mean difference (SMD), with 95% Confidence Intervals (CI). For similar studies the pooled WMD and SMD and 95% CI will be calculated. For pooled effects, a Breslow‐Day test of heterogeneity will be carried out and a p value <0.05 will be considered significant.
Subgroup comparisons to be considered will be:
Population‐ male vs. female
Severity AHI > or =to 20 and < 20 per hour
Sensitivity analysis will be to be performed using the domains:
1. Methodological quality ‐ CC criteria A vs. B&C
‐Jadad score 3‐5 vs. <3
2. Random effects vs. fixed effects modeling.
