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11th October 2021
Chronic urticaria (CU) is a recurrent skin condition characterised by hives, angioedema or both. The prevalence appears to vary across the world, with one 2020 review of studies indicating a prevalence of 1.4% in Asian, 0.5% in European and 0.1% in North American studies. The condition creates a huge burden on patients, markedly interfering with sleep, daily activities and overall quality of life. Interestingly, one study found that a quarter of patients with CU experienced sleep-related breathing disorders and in a small study of 31 patients with chronic idiopathic urticaria, 13 were diagnosed with obstructive sleep apnoea (OSA), one of whom had severe OSA.
Given that a proportion of patients with chronic urticaria have sleep-related breathing problems and even OSA, the precise nature of this relationship and whether CU and OSA are causally related remains uncertain. This led a team from the Department of Immunology and Pulmonary Medicine, San Jorge, Ecuador, to undertake a cross-sectional study among patients with CU to determine the frequency of OSA risk factors. Included patients were 18 years and over with a diagnosis of CU and all were screened using the STOP-Bang questionnaire, which is a highly sensitive screening tool for OSA. The “STOP” part of the questionnaire enquires about snoring, tiredness during the day, observed apnoea and high blood pressure, whereas the “Bang” part screens patients for a high body mass index (BMI > 35), age (> 50), neck circumference (> 40 cm) and male gender. Using STOP-Bang questionnaire, patients were categorised as low risk (scores 0 -2), intermediate risk (scores 3 – 4) and high ( scores 5 – 8). Patients deemed at intermediate risk were reclassified as high risk if they had two positive responses from the STOP part and were male and with a BMI > 35. In addition, patients completed the Urticaria Activity Score summed over 7 days (UAS7) which assesses itch severity and hive count. The USA7 categorises patients in terms of disease severity, with higher scores indicating more severe disease. Further questionnaires completed included a chronic urticaria quality of life questionnaire and the urticaria control test (UCT), which defines patients as being either poorly controlled or well-controlled.
A total of 171 patients with a mean age of 41.9 years (68.4% female) were included. The mean STOP-Bang score was 2.5 with 24% and 21% of patients classed as being at intermediate and high risk of OSA, respectively. There was a statistically significant association (Cramer’s V = 0.263, p < 0.001) between the UAS7 categories and the STOP-Bang risk categories. In fact, more than half of the subjects within the “moderate-severe” category (based on the UAS7 score) had an intermediate or high risk for moderate-to-severe OSA. There was also a significant association between UCT categories and STOP-Bang risk categories, such that 82.4% of patients with controlled urticaria had a low risk of OSA.
The authors concluded that their data suggested that a considerable proportion of patients with chronic urticaria were at intermediate to high risk for OSA, based on the STOP-Bang questionnaire. They added how further support for this conclusion came from the associations between higher disease activity and poor disease control. They called for more studies to determine the exact link between the two conditions.
Cherrez-Ojeda I et al. Chronic urticaria and obstructive sleep apnea: is there a significant association? World Allergy Org J 2021