Evaluation of a home respiratory polygraphy system in the diagnosis of the obstructive sleep apnea syndrome

Background: Recent recommendations advise against the use of portable home respiratory polygraphy systems for the diagnosis of the obstructive sleep apnoea syndrome (OSAS). Nevertheless such systems are widely used, particularly in France. Our aim was to assess the diagnostic value of one of these systems in the diagnosis of OSAS.

Methods: 65 consecutive patients were assessed prospectively, on account of suspicion of OSAS, by home respiratory polygraphy (HRP, Medcare Embletta). HRP confirmed severe OSAS [apnoea/hypopnoea index (AHI)>30/hr] in 8 patients. Those having AHI<30 hr or a failure of HRP (5 patients) were studied by full polysomnography in the sleep laboratory (PSG).

Results: In 52 patients the AHI obtained by HRP and analysed manually correlated weakly with that obtained by PSG (n=52; p<0.001; r=0.36). The AHI-PSG was 27.1+/-2.8/hr and the AHI-HRP was 12+/-0.9/hr. The mean difference (HRP-PSG) was 15.1+/-37.5/hr with poor concordance. A better cut off value in terms of efficacy of HRP was an AHI of 10/hr, with sensitivity of 61.4% and a specificity of 100%.

Conclusions: A negative result by HRP does not exclude OSAS and full PSG is required in patients suspected of having this condition.