Sleep Apnea. Concordance Between Non-reference and Reference Centres
Sleep Apnea. Concordance Between Non-reference and Reference Centres
When a disorder is as prevalent as sleep apnea hypopnea syndrome various medical levels and
 strategies should be implicated. We to evaluate the degree of concordance in management
 between a sleep reference centre and non-reference centres.
INTRODUCTION: When a disorder is as prevalent as SAHS, different medical levels should be
 involved to facilitate diagnosis for all patients, or at least those that are in
 moderate-severe or risk groups. A good option could be to transfer the patient assessment to
 non-reference centres (NRC). Therefore, the aim of the present study was to evaluate this
 strategy by analysing the degree of concordance between RC and NRC in treatment decision and
 management of SAHS patients.

 MATERIALS AND METHODS: Study subjects: The study population consisted of 88 consecutive
 subjects with a suspicion of SAHS (age 50±11 years, 81 % male, BMI 30±4 K/m2) from the
 out-patient clinics of three NRC in the Barcelona area: Hospital Asil de Granollers, Hospital
 General de Vic and Hospital de Terrassa.

 Study design: The patients were evaluated independently, at random, over the course of 1
 month in the RC and NRC. In both types of centre, the patient evaluation was carried out on
 the basis of the clinical history, with a specific questionnaire about sleep disordered
 breathing, and a sleep study in the hospital. The evaluation was performed by a sleep
 physician in the RC and by a respiratory physician with training in sleep medicine in the
 NRC. In both cases, the choice of treatment was registered on an ordinal scale with four
 points: 1= No diagnosis of SAHS and patient is discharged; 2= Mild SAHS, patient should
 follow a conservative treatment and clinical control; 3= Moderate to severe SAHS, patient
 should begin continuous positive air pressure (CPAP) treatment; 4= Other sleep disorders are
 diagnosed (RC), or there is a need for full-night PSG owing to a discordance between clinical
 features and respiratory polygraphy in NRC. The indication for CPAP treatment followed the
 national-SEPAR guidelines summarized as: 1) Patients with severe SAHS-related symptoms with
 an AHI>10; or 2) Patients with mild to moderate clinical symptoms with an AHI>30. The human
 ethics committee of our hospital approved the protocol and informed consent was obtained from
 all the patients. Sleep studies: Reference hospital: Full-night polysomnography was performed
 in the usual manner. Briefly, the variables registered were electroencephalogram, chin
 electromyogram, electro-oculogram, tibial electromyogram, arterial oxygen saturation, ribcage
 and abdominal motion and their sum. Airflow was measured by cannula/thermistor. An apnea was
 defined as the absence or airflow equal to or greater than 10 seconds. Hypopnoea 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 seconds. An expert
 technician scored sleep stages and respiratory variables manually. An apnea-hypopnoea index
 (AHI) equal to or greater than 10 was considered abnormal.Non-reference centres: patients
 received a respiratory poligraphy with recording of body position, ribcage and abdominal
 motion, snoring, arterial oxygen saturation and airflow using a cannula/thermistor. The
 respiratory physician performed a manual scoring of the recording. The definitions of
 hypopnoea and apnea resembled those mentioned above, except in the case of arousal. Data
 analysis: Data were entered using SPSS 10.0 and imported to STATA 7.0 to perform the analysis
 (StatatCorp. 1999. Stata Statistical software: Release 7.0. College Station, TX: Stata
 Corporation). Descriptive analysis: Data were expressed as mean ± SD or percentage for
 quantitative and qualitative variables, respectively. For continuum variables, a logarithmic
 transformation was undertaken to normalise 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, between the
 RF and the NFC centres, was performed by using the statistic Kappa balanced, penalizing
 extreme discrepancies, following the classification of Landis & Koch (25). This procedure was
 also used for the concordance in the result of the AHI of the sleep study, categorised as
 follows: <10, 10-29, ≥30. Concordance in the results of the sleep study (AHI and CT90) was
 evaluated in accordance with the Band & Altman methodology and the concordance coefficient of
 Lin.
Inclusion Criteria:

 -  Supected sleep apnea

 Exclusion Criteria:

 -  Major diseases