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Obstructive sleep apnea (OSA) occurs in at least 50% to 60% of patients with chronic kidney disease (CKD), which is 10 times higher than in the general population .The high incidence of nocturnal hypoxiemia associated with OSA causes oxidative stress, RAAS activation and endothelial dysfunction. This contributes to both loss of kidney function and increased cardiovascular morbidity in patients with CKD. This study aimed to estimate the prevalence of OSA in patients with CKD and analyse the distribution of OSA according to its severity in different stages of CKD. We also looked to identify modifiable risk factors to decrease progression of both OSA and CKD. Finally, we analysed the effect of RAASi use on severity of OSA in these patients.
Sixty-five adult patients with CKD (stages 1-5) attending out-patient department or admitted in hospital at Yashoda Super speciality Hospital, Somajiguda, Hyderabad were included in the study, after taking informed consent. This was a prospective observational study conducted between June 2019 to July 2021. A detailed medical history including details of existing co-morbidities, medications and symptoms suggestive of OSA was taken. Additionally patients were asked to complete 2 questionnaires - a lifestyle questionnaire (to assess risk factors and well being) and a questionnaire to assess daytime sleepiness (Epworth sleepiness scale). All patients underwent a detailed general physical examination which included height, weight, BMI, waist circumference, neck circumference and Mallampati scoring. Lastly, in addition to the standard blood test and cardiac evaluation, all patient underwent a polysomnography using the ALICE 6 diagnostic system. The tracing was scored using 30 second epochs. The parameters monitored were central and occipital EEG, electrooculogram (EOG), sub-mentalis EMG, nasal and oral airflow, thoracic and abdominal wall motion, anterior tibialis EMG, body position, electrocardiogram and oxygenation. The data was assessed and reported using WINDOWS software by a pulmonologist. Chi-Sqaure test was used to find the association between qualitative factors. To find the correlation between Epworth sleep scale and apnea hypopnea index, Pearson Correlation was used. P value less than 0.05 was considered significant.
In our study, the prevalence of OSA was very high in patients with chronic kidney disease. Although patients with chronic kidney disease tend to have severe OSA there was no correlation between the stages of CKD and severity of OSA.
The classical symptoms of OSA did not correlate with the prevalence or severity of OSA in patients with CKD. Therefore, patients with CKD must be evaluated for OSA regardless of the presence of symptoms. There was a significant correlation between Mallampati score and severity of OSA. Hence it may be used in patients with CKD as a screening technique to assess for OSA