WINNIPEG, MANITOBA—Cardiovascular disease is more prevalent among patients with obstructive sleep apnea syndrome (OSAS) than among non-apneic individuals. A new study shows that in the year preceding diagnosis, OSAS patients are 88% more likely than control subjects to use a prescription drug and are 2.7-fold more likely to take an antihypertensive.[1] This increased drug use translates to higher overall medication costs for those with undiagnosed OSAS.

“Epidemiological studies have shown that people with OSAS have more hypertension,” Meir H. Kryger, MD, Professor of Medicine at the University of Manitoba, said in an interview with RESPIRATORY REVIEWS. This finding prompted Dr. Kryger to explore the impact of undiagnosed OSAS on patients’ health care. He added, “I wanted to know what drugs they were taking and whether or not they actually were being treated by their family doctors” for OSAS sequelae.

To answer these questions, Dr. Kryger and colleagues examined entries to a prescription database for 549 OSAS patients (148 women) and 549 matched controls. During the year before OSAS diagnosis, 36.6% of OSAS patients but only 19.7% of controls received cardiovascular medications. Specifically, antihypertensive drugs were prescribed for 31.7% of the OSAS patients and for 16.4% of the controls.

Logistic regression revealed that antihypertensive use was predicted by age, body mass index, and apnea-hypopnea index (AHI); patients with an AHI of 60 were 65% more likely than controls to receive blood pressure medications. Interestingly, patients’ total medication costs increased with the extent of hypoxemia: “The more time they spent with a low blood oxygen level, the more likely they were to be spending more money on drugs,” said Dr. Kryger, who is also Director of the Sleep Disorders Centre at St. Boniface General Hospital in Winnipeg.

Statistics on antihypertensive use corroborated earlier findings of hypertension prevalence among sleep apnea patients. Yet this finding underscores widespread underdiagnosis of OSAS among hypertensive patients, Dr. Kryger stressed: “The irony is that a lot of them were being treated for complications of sleep apnea, and their doctors may not have known whether a sleep disorder was playing a role in their high blood pressure.”

Therefore, Dr. Kryger emphasized, “Family doctors need to start thinking about sleep apnea in their patients with hypertension.” A physician seeing a patient with hypertension, he stated, “should be asking a couple of questions: ‘Do you snore?’ and ‘Have you ever been told that you stop breathing?’ ” Overweight patients should also be considered to be at risk for sleep apnea, he added.

Asked whether corrective measures, such as continuous positive airway pressure (CPAP), could be cost-effective in reducing the need for cardiovascular care, Dr. Kryger responded, “It would be paid for very quickly.” Based on previous research, he said, “After two years, there is an overall reduction in medical utilization costs.” Although CPAP lowers blood pressure, he noted, “We don’t yet know whether treating these patients with CPAP is translated to a lowered cardiovascular morbidity.”

—Mimi Zucker, PhD