ORCADES Oral Appliance research
Clinical results for Narval CC™ – the ORCADES study | ResMed

Clinical results for Narval CC™ – the ORCADES study

Evaluating the efficacy and compliance of the Narval CC™ mandibular repositioning device (MRD): that is the purpose of ORCADES, the largest multicentre trial of patients with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) who are being treated with a custom-made MRD. The ongoing study follows 369 patients over a period of 5 years.1 158 patients - 43% of the study participants - have severe OSAHS (apnoea hypopnoea index (AHI)>30).

The aim of the ORCADES study is to provide solid clinical proof of the benefits of Narval CC in the treatment of snoring and OSAHS in routine practice. The 3-6 months follow-up results of the ORCADES study were published in the Sleep Medicine Journal in 2015; the 2 year follow-up results were  presented  at the ERS congress in September 2016  and published in the Sleep Medicine Journal in 2019.

In the 3 months analysis2, ORCADES looked at the difference in manufacturing process for Narval CC: out of the total sample, 312 patients were treated with a Narval CC produced with a computer-aided design and computer-aided manufacturing process (CAD/CAM), while 57 patients were treated with a Narval CC that used a “traditional” process (non-CAD/CAM). This allowed for sub-group analysis.

Efficacy in the reduction of AHI and symptoms

AHI efficacy:1-3

Narval CC conceived with CAD/CAM process is more effective in reducing AHI than a non-CAD/CAM MRD, regardless of the initial OSAHS severity.

  • Success rate (reduction of initial AHI ≥50%) of the Narval CC CAD/CAM MRD: 79% (CI 95%: 74-83 %) regardless of the initial severity of initial OSAHS; for the non-CAD/CAM MRD: 61% (CI 95%: 47-72%) ; p=0.0031
  • Complete response (AHI<10): CAD/CAM Narval CC: 66% (CI 95%: 61–72%) vs non-CAD/CAM: 49% (CI 95%: 36–62%); p=0.017
  • The Narval CC CAD/CAM MRD had three times the probability of success compared to the non-CAD/CAM MRD (OR=3.0, p=0.0035)

After 2 years, Narval CC efficacy on AHI remained positive in a majority of cases.3

  • Complete response (AHI<10) = 56% of OSAHS patients
  • Reduction of AHI < 15 (cardiovascular risks protection)

        - 84% of moderate OSAHS patients (patients who presented an AHI between 15 and 30 at the 1st inclusion visit);

        - 53% of severe OSAHS patients (patients who presented an AHI > 30 at the 1st inclusion visit);

        - 70% of patients maintain or improve their AHI reached at 3-6 months.

Efficacy in sub-groups:

  • In severe OSAHS patients (AHI>30 at inclusion): 61% obtained an AHI<15 at the 3 month follow-up (FU)1 and 53% of the patients still had an AHI<153 after 2 years of therapy.
  • In women: Whatever the baseline severity of OSA, efficacy at the 3 month FU is higher compared to men.4

Symptom efficacy:1,3

  • Significant efficacy on snoring
    • Patient self-reported data show the disappearance of bothersome snoring in more than 80% of patients after 3 months, with results maintained after 2 years (p<0.0001).

    • Objective snoring data measured by PSG after 2 years show a reduction of 75% (p<0.0001).

  • Sleepiness reduction: also improving over time. 4.4 points of reduction in the Epworth score (P<0.0001). 62% of patients with an initial Epworth score > 10 were no longer sleepy at 2 year FU.3

  • Significant improvement in quality of life: +24% increase in the Quebec sleep questionnaire (p<0.0001) after 3 months, which continues to improve after 2 years: + 29% increase in the Quebec questionnaire after 2 years (p<0.0001).

At 3 month FU, we saw a disappearance of libido problems in 81% of affected patients.2

Sleep efficacy (PSG data) measured after 3 months:2

  • Significant reduction in the number of micro-arousals regardless of OSAHS level: from 24.2 ± 17.5 evt/hr  to 16.1 ± 12.1 evt/hr (p<0.0001)
  • Significant increase in REM sleep duration in severe OSAHS patients: +3% (p=0.023)

Excellent compliance and tolerance maintained over time1,3

The Narval CC is well-tolerated by patients:1,2

• 85% of patients wore the device every night even after 2 years

• After 2 years, compliance was 6.7 hours/night and 6.7 nights/week (average sleep duration of 7 hours in the study).

• Only 8% of treatment withdrawal for adverse events and/or intolerance after 3 months1. This results remains stable after 2 years as the majority of side effects appears during the first weeks of treatment3.

The most frequent adverse events were minor and temporary.


  1. Vecchierini MF & al. A custom-made mandibular repositioning device for obstructive sleep apnoea-hypopnoea syndrome: the ORCADES study. Sleep Med. 2016 Mar;19:131-40. doi: 10.1016.
  2. Vecchierini MF & al. Impact of a custom-made mandibular repositioning device on blood pressure in obstructive sleep apnea patients noncompliant with continuous positive airway pressure. Abstract supplement. Sleep, 2015;(38).
  3. Attali V & al (for Orcades Study Investigators). Two year follow-up results of ORCADES study: Long-term mandibular repositioning device (MRD) therapy in patients treated for obstructive sleep apnea (OSA) - European Respiratory Journal 01 September 2016; Volume 48, issue suppl 60
  4. Vecchierini MF & al (for Orcades Study investigators). Gender-specific efficacy of Mandibular Repositioning Device (MRD) therapy in obstructive sleep apnea (OSA) patients. Subgroup analysis of ORCADES study data. 2016 JSR 25 (Suppl. 1),5–377

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