Longitudinal association of sleep-disordered breathing and nondipping of nocturnal blood pressure in the Wisconsin Sleep Cohort Study.
OBJECTIVE
The association of sleep-disordered breathing (SDB) and blunting of normal nocturnal lowering of blood pressure (BP) (nondipping) has only been examined cross-sectionally. The purpose of this study is to investigate whether SDB is prospectively associated with nondipping.


METHODS
The longitudinal association between SDB and incident nondipping was examined in a subsample of 328 adults enrolled in the Wisconsin Sleep Cohort Study who completed 2 or more 24-hour ambulatory BP studies over an average of 7.2 years of follow-up. SDB identified by baseline in-laboratory polysomnography was defined by apnea-hypopnea index (AHI) categories. Systolic and diastolic nondipping was defined by systolic and diastolic sleep-wake BP ratios > 0.9. All models were adjusted for age, sex, body mass index at baseline and follow-up, smoking, alcohol consumption, hypertension, sleep time, length of follow-up time, and antihypertensive medication use.


RESULTS
There was a dose-response increased odds of developing systolic nondipping in participants with SDB. The adjusted odds ratios (95% confidence interval) of incident systolic nondipping for baseline AHI 5 to < 15 and AHI > or = 15, versus AHI < 5, were 3.1 (1.3-7.7) and 4.4 (1.2-16.3), respectively (P trend = 0.006). The adjusted odds ratios (95% confidence interval) of incident diastolic nondipping for corresponding SDB categories were not statistically significant: 2.0 (0.8-5.6) and 1.3 (0.2-7.1).


CONCLUSIONS
Our longitudinal findings of a dose-response increase in development of systolic nondipping of BP with severity of SDB at baseline in a population-based sample provide evidence consistent with a causal link. Nocturnal systolic nondipping may be a mechanism by which SDB contributes to increased cardiovascular disease.
Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705-2276, USA. kmh@medicine.wisc.edu
Khin Mae
KM
Hla
Terry
T
Young
Laurel
L
Finn
Paul E
PE
Peppard
Mariana
M
Szklo-Coxe
Maryan
M
Stubbs
D015992:Body Mass Index; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000453:epidemiology*; D012907:Smoking / Q000453:epidemiology