Sleep Apnea. Concordance Between Non-reference and Reference Centres
Condition: Sleep Apnea
MeSH terms: Sleep Apnea Syndromes
Study type: Interventional
Phase: Phase 4

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): SAHS diagnosis
Intervention type(s): Procedure
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double
Primary purpose: Diagnostic
Keywords: breathing disorders