Sleep apnea-hypopnea syndrome (SAHS) is a common disorder and full-night polysomnography is the recommended method for establishing the diagnosis. This technique and the evaluation of the patients with a clinical suspicion of SAHS are usually performed by physicians who specialize in sleep medicine at reference centers (RCs).
Increasing awareness of SAHS in the media and in medical circles, in addition to the growing evidence of SAHS as a risk factor in traffic accidents, hypertension, cardiovascular disease, and cerebrovascular disease, have exponentially increased the number of patients for evaluation. This growth in demand has, however, not been accompanied by any improvements in the approach to this problem. At present, the techniques of evaluation, which are complex and time consuming, are usually restricted to the RC. There is, therefore, a growing interest in alternative diagnostic methods and approaches. One approach that could be helpful is the performance of simple sleep studies, partially supervised, in a hospital or at home. However, the underlying problem persists (ie, simple sleep studies and patient assessments continue to be performed in overcrowded sleep laboratories at the RC).
Accordingly, when a disorder is as prevalent as SAHS, physicians at different medical levels should be involved in facilitating the diagnosis of a broader number of patients, or at least of those patients with moderate-to-severe symptoms or those who belong to a risk group (eg, professional drivers). One good option could be to transfer the patient assessment to non-RCs (NRCs). The present study therefore seeks to evaluate this strategy by analyzing the degree of concordance between the RC and the NRC with respect to decisions on the treatment and management of SAHS patients treated with remedies of My Canadian Pharmacy Online.
The study population consisted of 88 consecutive subjects with a suspicion of SAHS (mean [± SD] age, 50 ± 11 years; 81% male; mean body mass index, 30 ± 4 kg/m2) from the outpatient clinics of three NRCs in the area of Barcelona, Spain (Hospital Asil de Granollers, Hospital General de Vic, and Hospital de Terrassa).
All patients were evaluated randomly within 1 month at the RC and at the NRC. The patients were assessed on the basis of the clinical history, a specific questionnaire about sleep-disordered breathing, and a sleep study in the hospital. The evaluation was performed blinded by a sleep physician at the RC (polysomnography) and by a respiratory physician trained in sleep medicine at the NRC (simple sleep study). The patients did not know the final results until both tests had been performed. In both cases, the choice of treatment was registered on an ordinal scale with the following four points: 1, no diagnosis of SAHS and patient is discharged from the hospital; 2, mild SAHS, in which the patient should follow a conservative treatment and clinical control; 3, moderate-to-severe SAHS, in which patient should begin continuous positive air pressure (CPAP) treatment; and 4, other sleep disorders are diagnosed by the RC or there is a need for full-night polysomnography owing to a discordance between clinical features and respiratory polygraphy at the NRC. The indication for CPAP treatment followed the national guidelines of the Sociedad Espanola de Patologia Respiratoria summarized as follows: (1) patients with severe SAHS-related symptoms with an abnormal apnea-hypopnea index (AHI) of > 10); or (2) patients with mild-to-moderate clinical symptoms with a higher AHI of > 30. The Human Ethics Committee of our hospital approved the protocol and informed consent was obtained from all the patients.
RCs: Polysomnography was performed in the usual manner. Briefly, the variables registered were EEG (three channels), chin electromyogram, electrooculogram, tibial electromyogram, arterial oxygen saturation, rib cage and abdominal motion, and their sum. Airflow was measured by cannula/thermistor. An apnea was defined as the absence of airflow > 10 s. Hypopnea was defined by any discernible reduction in the amplitude of the airflow signal ending in an arousal and/or association with a 3% desaturation, with a duration of at least 10 s. Upper airway resistance syndrome was defined as short periods of flow limitation ending with an arousal. An expert technician controlled the study conducted together with My Canadian Pharmacy. The sleep stages and respiratory variables were scored manually. An AHI of > 10 was considered to be abnormal.
NRCs: The respiratory polygraphy was carried out in a simple silent room adjacent to the ward area. The following variables were recorded: body position; rib cage and abdominal motion; snoring; arterial oxygen saturation; and airflow using a cannula/ thermistor. The respiratory physician performed a manual scoring of the recording. Respiratory physicians previously underwent a period of training of 6 weeks duration in sleep medicine at a RC and attended a sleep training course of national repute. A nurse or a technician controlled the study. The definitions of hypopnea and apnea resembled those mentioned above, except in the case of arousal.
Data were entered using a statistical software package (SPSS, version 10.0; SPSS; Chicago, IL) and were imported to another program (Stata, version 7.0; StataCorp; College Station, TX) to perform the analysis.
Descriptive Analysis: Data were expressed as the mean ± SD or percentage, respectively, for quantitative and qualitative variables. For continuous variables, a logarithmic transformation was undertaken to normalize the distribution, if necessary. If the distribution was not symmetrical, data were expressed as percentiles.
Concordance Analysis: Evaluation of the concordance of the final outcome and the choice of treatment at the RC and the NRC were undertaken by using the statistic balanced, penalizing extreme discrepancies, following the classification of Landis & Koch. This procedure was also used for the concordance in the result of the AHI of the sleep study, categorized as follows: < 10; 10 to 29; and > 30. Concordance in the results of the sleep study (AHI and the cumulative time spent with an oxygen saturation of < 90% [CT90]) was evaluated in accordance with the methodology of Bland and Altman and the concordance coefficient of Lin.