Introduction:
Obstructive sleep apnea (OSA) is a recognized risk factor for the development of diabetic kidney disease (DKD) as it is linked to impaired glycemic control. However, the impact of apnea-hypopnea suppression on DKD progression remains unclear. Despite increasing evidence of the association between OSA and DKD, the ability of continuous positive airway pressure (CPAP) to reduce the progression of DKD has been lacking.
Our primary objective was to assess the effect of CPAP on urinary albumin-to-creatinine ratio (UACR) in patients with both DKD and OSA while the secondary objectives included evaluation of CPAP’s impact on estimated glomerular filtration rate (eGFR), serum creatinine, potassium and HbA1c concentrations starting from baseline to 36 weeks. Additional metrics included changes in body weight, blood pressure, sleepiness, health-related quality of life, and daily physical activity over 36 weeks.
Methods:
Study Design: It was a single-centered, open-label, randomized clinical trial comparing CPAP to usual care for reducing UACR in patients with both OSA and DKD. Study was conducted according to the Declaration of Helsinki and Good Clinical Practice guidelines after obtaining approval from the Institutional Ethics Committee.
Participants: Fifty type 2 diabetes patients aged 18-70 years with OSA and DKD who were on stable doses of angiotensin-converting enzyme(ACE) inhibitors, angiotensin II receptor blockers (ARB) or aldosterone receptor antagonists (MRA) for minimum of 4 weeks, and provided informed written consent were included in the study.
Randomization: Participants were eligible for randomization if apnea–hypopnea index(AHI) was ≥10 events/hour. They were randomly assigned (1:1) to either ‘CPAP plus usual care’ group (n=25) or ‘usual care alone’ group (n=25).
Methodology: Sleep test was performed for patients allocated to the CPAP group at home using a validated portable monitor. They received continuous positive airway pressure through an automated machine. The CPAP device used (S9 or S10, ResMed) recorded all the data from baseline to 9 months of use.
Assessments were carried out at baseline, 12, 24, and 36 weeks respectively. Anthropometrics, blood pressure, heart rate, co morbidities, medications, cardiovascular events, sleepiness (ESS),quality of life (EQ-5D),and physical activity (IPAQ) were measured at every visit. Early-morning urine and blood samples were collected to measure UACR, eGFR, creatinine, potassium, HbA1c, albumin, lipid profile, homocysteine and high-sensitivity C-reactive protein.
Statistical Analysis: Sample size of 21 per group was needed for 80% power to detect a 0.36 change in UACR. ANCOVA compared changes in log-transformed UACR between CPAP and control groups, with baseline UACR, eGFR, HbA1c, mean arterial pressure, Body Mass Index, and AHI as covariates. For comparisons Student’s t test, Mann-Whitney U test, ANOVA, and chi-square tests were used. Significance was set at 0.005, analyzed using SPSS version 24.0.
Results:
Fifty eligible patients were randomly assigned to either ‘CPAP plus usual care’ group (n=25) or ‘usual care alone’ (n=25)group. Of these, 20 (80%) in the CPAP group and 23 (92%) in the usual-care group maintained adequate adherence (Adequate adherence was defined as at least 4 hours/night over 9 months).Significant improvement in UACR was found in OSA patients with good compliance to CPAP treatment and usual care after 9 months of therapy (baseline vs 9-month follow-up, 22.0±9.5 vs 11.2±6.5mg/g, respectively, P=0.005)whereas, slight worsening in UACR was noted in patients assigned to the group receiving only usual care (13.7±4.4 vs 16.1±6.3mg/g, respectively, P=0.39).Statistically significant results also revealed that higher the baseline UACR (i.e., the larger the difference from normal levels), greater was the effect of CPAP treatment. CPAP additionally improved glycemic control, sleepiness and health-related quality of life.
Conclusions:
In patients with OSA and DKD, the prescription of CPAP for 9 months resulted in a statistically significant reduction in UACR. Thus, measuring UACR can be a simple way to assess CPAP compliance and effectiveness in the future. Further research is needed to determine if UACR improvement is linked with reductions in other comorbidities.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.