People with obstructive sleep apnoea (OSA) have a higher risk of developing cancer, an increase in blood clots and experience a decline in mental processing powers, a European conference has heard.
Three studies were presented to the European Respiratory Society (ERS) International Congress in Barcelona, Spain, about the common sleep disorder, which is believed to affect at least 7 to 13% of the population.
The first study, led by Dr Andreas Palm, a researcher and senior consultant at Uppsala University, Sweden, examined the risk of cancer among people with OSA.
They looked at data from 62,811 patients in Sweden, five years prior to the start of treatment for OSA.
Between July 2010 and March 2018, patients were treated with continuous positive airway pressure (CPAP), and this information was linked with data from the Swedish National Cancer Registry and socio-economic data from Statistics Sweden.
After accounting for factors that could affect the results, such as body size, other health problems and socio-economic status, the team matched 2,093 OSA patients and a diagnosis of cancer up to five years before OSA diagnosis with a control group of 2,093 OSA patients who had no cancer.
When they measured the severity of OSA with the apnoea hypopnea index (AHI) or desaturation index (ODI), they found patients with cancer had slightly more severe OSA, as measured by an apnoea hypopnea index average of 32 versus 30, and an oxygen desaturation index of 28 versus 26.
In further analysis of subgroups, ODI was higher in patients with lung cancer (38 versus 27) prostate cancer (28 versus 24) and malignant melanoma (32 versus 25).
“The findings in this study highlight the need to consider untreated sleep apnoea as a risk factor for cancer and for doctors to be aware of the possibility of cancer when treating patients with OSA,” said Dr Palm.
“However, extending screening for cancer to all OSA patients is not justified or recommended by our study results.”
The second study, presented by Professor Raphaël Heinzer, director of the Centre for Investigation and Research on Sleep (CIRS) at Lausanne University, Switzerland, showed that OSA was linked to a greater decline in mental processing powers over five years.
Professor Heinzer, Dr Nicola Marchi, of Lausanne University Hospital, and colleagues studied 358 people aged 65 years and over in Lausanne, who were recruited to the CoLaus/PsyCoLaus and HypnoLaus studies between 2003 and 2008.
They took a sleep test to examine the presence and severity of OSA when they joined the studies and during the first follow-up between 2009 and 2013, their mental processing abilities were also tested and another cognitive assessment took place five years later.
The cognitive tests assessed global cognitive function, processing speed, executive function, verbal memory, language and visual perception of spatial relationships between objects.
Speaking before the congress, Dr Marchi said: “We found that OSA and, in particular, low oxygen levels during sleep due to OSA, was associated with a greater decline in global cognitive function, processing speed, executive function and verbal memory. We also found that people aged 74 and older and men were at higher risk of cognitive decline related to sleep apnoea in some specific cognitive tests.”
The third study, presented by Professor Wojciech Trzepizur, from Angers University Hospital, France, showed that patients with more severe OSA were more likely to develop venous thromboembolism (VTE).
In what is the first study to investigate the association between OSA and unprovoked venous thromboembolisms, they found out of 7,355 patients followed over more than six years, 104 developed VTEs.
“We found that those who spent more than 6% of their night-time with levels of oxygen in their blood below 90% of normal had an almost two-fold risk of developing VTEs as compared to patients without oxygen deprivation,” said Prof Trzepizur.
“Further studies are required to see whether adequate treatment for OSA, for instance with CPAP treatment, might reduce the risk of VTEs in patients with marked nocturnal oxygen deprivation.”
Abstract no: OA2290 *Cancer prevalence is increased in obstructive sleep apnea – the population-based DISCOVERY study*, presented by Andreas Palm.
Abstract no: OA2287 *Obstructive sleep apnea and cognitive decline in the elderly population: the HypnoLaus study*, presented by Nicola Andrea Marchi.
Abstract no: OA2288 *Sleep apnea and incident unprovoked venous thromboembolism: Data from the French Pays de la Loire Sleep Cohort*, presented by Wojciech Trzepizur.
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