|Should patients with sleep apnoea/hypopnoea syndrome be diagnosed and managed on the basis of home sleep studies
|Parra O, Garcia-Esclasans N, Montserrat J M, Eroles L G, Ruiz J, Lopez J A, Guerra J M, Sopena J J
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
A portable monitor of respiratory parameters (PMRP) in a home setting versus full-polysomnography (full-PSG) in the sleep laboratory for the diagnosis of patients with suspected sleep apnoea/hypopnoea syndrome (SAHS).
Economic study type
Community. The economic study was performed in Barcelona, Spain.
Dates to which data relate
Source of effectiveness data
The evidence for the final outcomes was derived from a single study.
Link between effectiveness and cost data
The costing for the intervention was prospectively performed on the same patient sample as that used in the effectiveness analysis. The costing for the comparator was based on its standard cost in the study institution.
Power calculations were not used to determine the sample size. A total of 89 consecutive patients with an average (SD) age of 54 (12) years were included in the study sample. Full-PSG in a sleep laboratoryand PMRP in the patient's home were performed randomly on the same patient sample within a 1 month period. In performing PMRP, 50 cases were carried out with a technologist's intervention in the set-up of the equipment and 39 cases with the patient's own set-up.
The study was a case-series, carried out in a single medical centre and patients' homes. No loss to follow-up was reported.
Analysis of effectiveness
It was not specified whether the analysis of effectiveness was based on intention to treat or treatment completers only. The primary clinical outcomes were the percentage of patients diagnosed as having SAHS (apnoea/hypopnoea index (AHI)>10), the mean AHI, the mean apnoea index (AI), the mean hypopnoea index (HI), the level of agreement between the two diagnostic tests employing the Bland and Altman method, the sensitivity and specificity of PMRP with reference to full-PSG-AHI>10, and the level of agreement between the clinical therapeutic decision taken after each diagnostic method.
Based on the results of PMRP, 82% of patients were diagnosed as having SAHS (AHI>10) as opposed to 84% based on full-PSG. PMRP had amean (SD) AHI of 31.8 (27) versus 34.3 (25) for full-PSG (not significant); the mean apnoea index (AI), was 10.9(16) for PMRP versus 8.7 (13.9) for full-PSG, (P<0.05); the mean hypopnoea index (HI) was 20.5 (14.2) versus 25.5 (19.7), respectively (P<0.05). The level of agreement between the two diagnostic tests employing the Bland and Altman method demonstrated a mean bias of 2.56 with a 95% Confidence Interval of 3.25 (not significantly different from zero). The sensitivity and specificity of PMRP with reference to full-PSG-AHI>10 depended on the PMRP-AHI cut-off point chosen. The sensitivity of PMRPincreased from 63% for a cut-off point of 23 to 95% for a cut-off point of 8. The specificity of PMRP decreased from 93% for a cut-off point of 23 to 33% for a cut-off point of 8. There was an 89% agreement between the clinical therapeutic decision taken after the two diagnostic methods.
The acceptable agreement between PMRP-AHI and full-PSG-AHI makes the former a valid method, despite its tendency to underestimate hypopnoeas. The diagnostic usefulness of the domiciliary method is supported by its acceptable sensitivity and specificity. Furthermore, in most cases, the clinical decision to treat based on the PMRP results is in agreement with that from full PSG.
Measure of benefits used in the economic analysis
No summary benefit measure was identified in the economic analysis, and only separate clinical outcomes were reported.
The resource quantities were not reported separately from the costs. The cost components were reported separately. The cost calculations for the intervention consisted of the costs of single-use materials, technician, false-negatives, establishing the new method, repetition of studies, unachievable studies, repairs and the travel costs of a technician in visiting a patient's home. The cost analysis was performed on the basis of an assumed output of 200 studies per year and a 5-year time span for the linear depreciation of the equipment. The cost associated with the comparator was reported as the standard price in the study institution. The perspective adopted in the cost analysis was not explicitly specified. The price date was not specified.
Spanish pesetas (Pta). A conversion to US dollars ($) was carried out.
No sensitivity analysis was performed.
Estimated benefits used in the economic analysis
PMRP with and without a technologist's intervention had an average total cost of Pta17,968.5 ($148.5) and Pta17,254.6 ($142.6), respectively. A full-PSG had a cost of Pta52,477.7 ($433.7).
Synthesis of costs and benefits
Costs and benefits were not combined since the use of PMRP was regarded as the weakly dominant strategy.
The authors believed "that patients with a suspected sleep apnoea/hypopnoea syndrome should initially be studied in a home setting with a portable monitor of respiratory parameters, since it is a reliable method with an acceptable cost-effectiveness profile".
CRD COMMENTARY - Selection of comparators
A justification was given for the choice of the comparator. It represented the gold standard in the context in question. You, as a database user, should consider whether this is a widely used health technology in your own setting.
Validity of estimate of measure of benefit
The estimates of effectiveness are likely to be internally valid.
Validity of estimate of costs
Resource utilisation was not reported separately from the costs. Adequate detail of the methods of cost estimation were not given, particularly in respect to the cost estimation related to the comparator.
In view of the lack of both sensitivity analysis, and statistical analysis of the costs, results need to be treated with some caution. The issue of generalisability to other settings or countries was addressed by the authors.
Source of funding
Supported by Grants 94/1006 from Fondo de Investigaciones Sanitarias de la Seguridad Social (FIS).
Parra O, Garcia-Esclasans N, Montserrat J M, Eroles L G, Ruiz J, Lopez J A, Guerra J M, Sopena J J. Should patients with sleep apnoea/hypopnoea syndrome be diagnosed and managed on the basis of home sleep studies. European Respiratory Journal 1997; 10(8): 1720-1724
Other publications of related interest
Comment in: European Respiratory Journal 1997;10(8):1699-700.
Subject indexing assigned by NLM
Adult; Evaluation Studies as Topic; Female; Health Care Costs; Humans; Male; Middle Aged; Polysomnography /economics /instrumentation /methods; ROC Curve; Respiration Disorders /diagnosis /therapy; Self Care; Sleep Apnea Syndromes /diagnosis /therapy; Syndrome
Date bibliographic record published
Date abstract record published