Purposes: The purposes of this study are to investigate the usefulness of polygraphy (PG) in diagnosing obstructive sleep apnea (OSA) in sleepy/tired snorers compared to polysomnography (PSG) and, further, to search for suspected respiratory arousals in the PG.
Methods: One hundred eighty-seven adults suffering from sleepiness/tiredness and snoring had undergone ambulant PG and were considered to be normal, using American Academy of Sleep Medicine's 2007 hypopnea criteria A. After approximately 7 months, in-lab PSG was performed using hypopnea criteria B, where arousals are also recognized. Validated questionnaires (Hospital Anxiety and Depression Scale, self-rated general health) were answered. In a subgroup, the sensitivity and specificity were calculated for flow limitation index (FLI) and flattening index (FlatI) in PG compared with the respiratory distress index (RDI) in PSG.
Results: Despite the normal PG, at PSG, the median RDI was 11.0 (range, 0-89.1). One hundred sixty-eight out of one hundred seventy-eight (90%) were found to have at least mild OSA and 119/187 (64%) with moderate-severe OSA according to the RDI values. The sensitivity and specificity were low (<70%) for FLI and FlatI. Forty-nine percent of the patients rated anxiety at borderline or pathological levels, 35% rated corresponding depression levels, and 45% rated poor or fair general health.
Conclusions: PG was insufficient to rule out OSA when the respiratory events were mainly associated with arousals. Almost half of these patients experience low general health and psychiatric problems. We recommend a full-night PSG when PG is "normal", and patients have symptoms of snoring and sleepiness/tiredness.