Pharmacists are often asked to help people with sleep problems and insomnia and obstructive sleep apnoea (OSA) each affect between 10 and 30 per cent of the general population.

Now a new study suggests that co-morbid insomnia and OSA (COMISA) is associated with a 47 per cent increase in mortality compared with controls who did not experience either problem.

“Previously, little was known about the impact of COMISA but what we did know was that for people with both conditions, health outcomes are consistently worse than those with neither condition or those with either condition alone,” says lead author Dr Bastien Lechat from Flinders University, Adelaide, Australia.

Researchers followed 5,236 people aged, on average, 63 years, for a median of 11.8 years, during which 21.1 per cent of those enrolled died.

At baseline, 52 per cent had neither insomnia nor OSA, 42 per cent had OSA only, 3 per cent had insomnia alone and 3 per cent had COMISA.

Compared with controls and adjusting for confounders, people with COMISA were twice as likely to have hypertension and 70 per cent more likely to have cardiovascular disease (CVD).

People with insomnia alone and OSA only were more likely to have hypertension than controls, by 97 and 23 per cent respectively, but no significant difference emerged with CVD.

Allowing for confounders, including diabetes, CVD and hypnotic use, COMISA was associated with a 47 per cent increase in all-cause mortality. No significant difference in all-cause mortality arose with either insomnia or OSA alone.

The association between COMISA and mortality was consistent across several definitions of OSA and insomnia.

The authors comment that the link between COMISA and mortality may reflect short sleep duration, poor cardiovascular health and a higher apnoea-hypopnoea index, a measure of OSA severity (the study, however, controlled for each of these).

They suggest that future research should also control for treated and untreated mental health symptoms and diagnosed psychiatric conditions, consider underlying mechanisms, determine if these associations are causal and whether treatment reduces mortality.

“Specific treatments may be needed for people with co-occurring disorders so it is important we examine the efficacy of insomnia and sleep apnoea treatments in this specific population,” says Dr Lechat.

“This is the first study to assess mortality risk in participants with co-morbid insomnia and sleep apnoea,” Dr Lechat adds.

“Given that these people are at higher risk of experiencing adverse health outcomes, it is important that people undergoing screening for one disorder should also be screened for the other.”

(European Respiratory Journal DOI:10.1183/13993003.01958-2021)