Which came first, obstructive sleep apnea or hypertension? A retrospective study of electronic records over 10 years, with separation by sex

Objectives Obstructive sleep apnea (OSA) is a risk factor for hypertension (HTN), but the clinical progression of the sleep disorder to the high blood pressure condition is unclear. There are also sex differences in prevalence, screening and symptoms of OSA. The objective was to estimate the time from OSA to HTN diagnoses, with sex-specific quantification. Design Retrospective analysis of electronic health records (EHR) over a 10-year period (2006 to 2015 inclusive). Setting UCLA Health System in Los Angeles, California, USA. Participants 4848 patients: female N=2086, mean [age±std] = 52.8±13.2 years; male N=2762, age=53.8±13.5 years. These patients were selected from 1.6 million patients with diagnoses in the EHR who met the criteria of: diagnoses of OSA and HTN; in long-term care defined by ambulatory visits at least one year prior and one year subsequent to the first OSA diagnosis; no diagnosis of OSA or HTN at intake; and a sleep study performed at UCLA. Primary and secondary outcome measures The primary outcome measure in each patient was time from the first diagnosis of OSA to the first diagnosis of HTN (in days). Since HTN and OSA are progressive disorders, a secondary measure was relationship between OSA-to-HTN time and age. Results The mean, std and 95% confidence intervals of the time from OSA to HTN diagnoses were: all - 732 ± 1094.9 [-764.6, -701.8] days; female -815.9 ± 1127.3 [-867.3, -764.2] days; and male -668.6 ± 1065.6 [-708.1, -626.8] days. Age was negatively related to time from OSA to HTN diagnosis in both sexes. Conclusions HTN was on average diagnosed years prior to OSA, with a longer separation in females. Our findings suggest under-screening of OSA, more so in females than males. Undiagnosed OSA may delay treatment for the sleep disorder and perhaps affect the development and progression of HTN. Brief Summary Strengths and limitations of this study ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial n/a ### Funding Statement This work was supported by NIH NR017435 (PMM) and NR017350 (EA), and National Center for Advancing Translational Science (NCATS) UCLA CTSI Grant Number UL1TR001881. ### Author Declarations All relevant ethical guidelines have been followed; any necessary IRB and/or ethics committee approvals have been obtained and details of the IRB/oversight body are included in the manuscript. Yes All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Data are publicly available in an online repository.