Obstructive sleep apnea (OSA) is the most common type of sleep apnea is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in blood oxygen saturation. These pauses in breathing, called apneas (literally, "without breath"), typically last 20 to 40 seconds.

The individual with OSA is rarely aware of having difficulty breathing, even upon awakening. It is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body (sequelae). OSA is commonly accompanied with snoring.

Psoriasis is a common chronic disease characterized by recurrent exacerbations of thickened, erythematous, and scaling plaques. It is universal in occurrence and affects approximately 2 percent of the US population. It is equally common in males and females. The mean age of onset is 27 years, with approximately 50 percent of cases occurring in the most productive years between the ages of 20 and 60; however, the age of onset is widely variable from infancy to old age.

Researchers using data from the Taiwan "Longitudinal Health Insurance Database 2000" investigated the risk of psoriasis or psoriatic arthritis in patients with obstructive sleep apnea (OSA). The study consisted of 2,258 patients with OSA and 11,255 matched comparison patients as the study cohort. Each subject was individually traced for a three-year period to identify patients who had been diagnosed with psoriasis during the follow-up period. The results showed that of the 13,513 sampled subjects, 0.27% (n=36) had psoriasis during the three-year follow-up period; the percentage was 0.49% and 0.22% for sampled subjects with and without OSA, respectively. The risk of psoriasis during the three-year follow-up period was 2.30 times greater for patients with OSA than for comparison patients. The authors concluded “Our results suggest that OSA is associated with an increased risk of subsequent psoriasis or psoriatic arthritis.”<sup>1

1</sup> Yang YW, Kang JH, Lin HC. Increased risk of psoriasis following obstructive sleep apnea: A longitudinal population-based study. Sleep Med. Jan2012.