Women’s Health
Relationship Between Kidney Stones and risk of incident Hypertension Among Postmenopausal Women Mahsa H Javadi* Mahsa H Javadi Danielle J Harvey Bernhard Haring Nora Franceschini JoAnn E Manson Matthew Allison John Robbins Lorena Garcia
Background:
Kidney stones have been linked to an increased risk for hypertension. The relationship between hypertension and kidney stones is influenced by interconnected factors like obesity, diet, and sedentary lifestyle. However, existing data lacked adjustment for a wide range of confounding variables. Also, the role of obesity as a potential effect modifier in this relationship remains unknown.
Objectives:
To evaluate whether self-reported kidney stones are associated with incident hypertension in postmenopausal women in the Women’s Health Initiative (WHI).
Methods:
In a prospective cohort study of 89,769 postmenopausal women ages 50-79 years without hypertension (HTN) at baseline, data from the WHI observational study and clinical trials were analyzed to assess the association between kidney stones and incident HTN. Kidney stone status was self-reported at baseline and during follow-up, treated as a time-varying, dichotomous variable (with 4,524 women reporting kidney stones at some point and 85,245 reporting no kidney stones). Incident hypertension was identified based on self-reported diagnosis of hypertension, blood pressure (BP) >130/80 mmHg on at least two separate occasions, or use of anti-hypertensive medications. At baseline, demographic and health history information were self-reported, while dietary data were collected using a validated food frequency questionnaire. Key covariates included age, metabolic factors (osteoporosis, diabetes, high cholesterol, body mass index (BMI), waist circumference, and waist-to-hip ratio (WHR)), lifestyle risk factors (Dietary Approach to Stop Hypertension (DASH), total energy expended from recreational physical activity, history of alcohol use and smoking, sociodemographic conditions (race, ethnicity, neighborhood socioeconomic status (NSES), and region of residence).
Temporal changes in Systolic BP (SBP) and Diastolic BP (DBP) in relation to a history of kidney stones were examined. The analysis assessed how mean SBP and DBP levels varied over 28 years among participants reporting kidney stones at some point and without a history of kidney stones. Two-sample t-tests were applied to compare the mean differences of each continuous variable between participants with and without hypertension. Chi-square tests were used to compare the two groups on categorical variables. Cox proportional hazards models assessed the association of kidney stone and incident hypertension adjusting for potential confounders. Cox regression models was conducted with the following models: Model 1adjusted for age at baseline; Model 2 additionally adjusted for metabolic factors; Model 3 added lifestyle-related risk factors to Model 2; Model 4 additionally included sociodemographic covariates; Model 5 added use of thiazide diuretics to Model 4.
Results:
Mean age for all participants was 62.5 (±7.17). Mean WHR differed slightly between groups [0.81 (±0.81) in kidney stone, 0.79 (±0.07) in no kidney stone, p<0.0001]. The racial/ethnic distribution was similar between participants with and without a history of kidney stones. Additionally, participants with a history of kidney stones tended to have lower NSES, [73.4 (±8.5) in kidney stone, 75.2 (±7.3) in no kidney stone, p<0.0001]. Kidney stone history is associated with lower levels of dietary calcium intake (807 (±475.78) mg/day vs 837 (±464.88) mg/day), lower levels of Vitamin D intake (4.26 (±3.24) mcg/day vs 4.33 (±3.04) mcg/day), lower total energy expenditure (12.93 (±14.14) Met-hours/week vs 13.79 (±14.24) Met-hours/week), a higher rate of osteoporosis-related fractures (2.19% vs 1.54%), and a higher rate of hormone replacement therapy use (71.09% vs 69.19%) compared to those without a history of kidney stones.
Over a mean follow-up of 17.5 years for the no kidney stone group, 44.2% developed hypertension compared to 43.1% over 15.4 years in the kidney stone group. Systolic and diastolic BP increased by about 14 mmHg and 12 mmHg during follow-up, respectively, which were not significantly different by kidney stone group (p=0.3).
A report of kidney stones was associated with increased risk of hypertension. The crude hazard ratio (HR) for incident hypertension was 1.27, 95% CI (1.23, 1.32), p<0.0001. After adjustment for age, metabolic factors, lifestyle risk factors and sociodemographic conditions, the multivariable-adjusted HR was 1.21, 95% CI of (1.16, 1.25), p<0.0001].
Conclusion:
Kidney stones are associated with an increased risk of hypertension in postmenopausal women. Individuals with a history of kidney stones may represent a high-risk group that could be targeted for early lifestyle/behavioral and other hypertension-prevention strategies.