Fluid intake and risk of stress, urgency, and mixed urinary incontinence

OBJECTIVE

We investigated the relation between total fluid intake and incident urinary incontinence in the Nurses' Health Study cohorts.

STUDY DESIGN

We measured daily fluid intake using food frequency questionnaires among 65,167 women, who were 37-79 years old, without urinary incontinence at study baseline (2000-2001). Women reported incontinence incidence on questionnaires during 4 years of follow-up evaluation. Multivariable-adjusted hazard ratios and 95% confidence intervals were calculated with Cox proportional hazards models.

RESULTS

We found no association between total fluid intake and risk of incident incontinence (hazard ratio, 1.04; 95% confidence interval, 0.98-1.10; comparing top vs bottom quintile of fluid intake). In analyses of incontinence type, total fluid intake was not associated with risks of incident stress, urgency, or mixed incontinence.

CONCLUSION

No significant risk of incident urinary incontinence was found with higher fluid intake in women. These findings suggest that women should not restrict their fluid intake to prevent incontinence development.

Quantification of urinary stone volume: attenuation threshold-based CT method--a technical note

PURPOSE

To compare two threshold-based computed tomographic (CT) methods for the quantification of urinary stone volume; to assess their accuracy and precision at varying tube voltages, tube currents, and section thicknesses in a phantom; and to determine interobserver agreement with each of these methods in a pilot clinical study.

MATERIALS AND METHODS

After institutional review board approval, written informed consent was waived. The study was HIPAA compliant. Thirty-six calcium oxalate stones were scanned in an anthropomorphic phantom. For the fixed threshold method, stones were segmented with 0.6-mm-thick sections by using attenuation thresholds of 130 and 575 HU (equal to half of mean attenuation of all stones). For the variable threshold method, stones were segmented at an attenuation threshold equal to half of the attenuation of each stone and at variable section thicknesses (0.6, 1, and 3 mm), tube currents (150, 100, and 50 mAs [reference]), and tube voltages (100 and 80 kVp). Normalized Bland-Altman analysis was used to assess the bias and precision of the two CT methods compared with that of the fluid displacement method (reference standard). Two independent readers retrospectively measured stone volumes in 17 patients (male-to-female ratio, 1.4; mean age, 55 years), and interobserver agreement was assessed by using Bland-Altman limits of agreement.

RESULTS

The variable threshold method was more accurate and precise than the fixed threshold method with an attenuation threshold of 130 HU (P < .0001). Thinner sections (0.6 and 1 mm) resulted in more accurate (P < .05) and precise (P < .0001) stone volume measurements than 3-mm-thick sections. With the variable threshold method, no significant difference was seen in the accuracy and precision of stone volume measurements at various tube currents and tube potentials. Interobserver agreement was high with the fixed and variable threshold methods (r > 0.97).

CONCLUSION

An attenuation threshold-based CT method can be used to quantify urinary stone volume even at low radiation doses. The most accurate and precise method utilizes variable attenuation derived from the attenuation of each stone and thin sections.

Plasma fibroblast growth factor 23, parathyroid hormone, phosphorus, and risk of coronary heart disease

BACKGROUND

Fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and phosphorus all have been proposed as plasma biomarkers for the development of coronary heart disease (CHD) in individuals with normal renal function.

METHODS

In a nested case-control study of men in the Health Professionals Follow-up Study, free of diagnosed cardiovascular disease at blood draw, we prospectively examined associations between plasma FGF23, PTH, and phosphorus and risk of CHD. During 10 years of follow-up, 422 men developed nonfatal myocardial infarction or fatal CHD. Controls were selected in a 2:1 ratio and matched for age, date of blood collection, and smoking status.

RESULTS

Mean estimated glomerular filtration rate was 86 mL/min per 1.73 m(2) in cases and controls. At baseline, there were no statistically significant differences between cases and controls in plasma levels of FGF23, PTH, or phosphorus. After adjusting for matching factors, family history of myocardial infarction, body mass index, alcohol consumption, physical activity, history of diabetes mellitus and hypertension, ethnicity, region, plasma 25-hydroxyvitamin D, and other factors, the odds ratios for incident CHD for participants in the highest, compared with lowest, quartiles were 1.03 (95% CI 0.70-1.52, P for trend 0.84) for FGF23, 1.20 (95% CI 0.82-1.76, P trend 0.99) for PTH, and 0.72 (95% CI 0.51-1.02, P trend 0.13) for phosphorus.

CONCLUSIONS

Plasma FGF23, PTH, and phosphorus are not associated with the development of incident CHD in men without chronic kidney disease.

Association between passive and active smoking and incident type 2 diabetes in women

OBJECTIVE

Accumulating evidence has identified a positive association between active smoking and the risk of diabetes, but previous studies had limited information on passive smoking or changes in smoking behaviors over time. This analysis examined the association between exposure to passive smoke, active smoking, and the risk of incident type 2 diabetes among women.

RESEARCH DESIGN AND METHODS

This is a prospective cohort study of 100,526 women in the Nurses' Health Study who did not have prevalent diabetes in 1982, with follow-up for diabetes for 24 years.

RESULTS

We identified 5,392 incident cases of type 2 diabetes during 24 years of follow-up. Compared with nonsmokers with no exposure to passive smoke, there was an increased risk of diabetes among nonsmokers who were occasionally (relative risk [RR] 1.10 [95% CI 0.94-1.23]) or regularly (1.16 [1.00-1.35]) exposed to passive smoke. The risk of incident type 2 diabetes was increased by 28% (12-50) among all past smokers. The risk diminished as time since quitting increased but still was elevated even 20-29 years later (1.15 [1.00-1.32]). Current smokers had the highest risk of incident type 2 diabetes in a dose-dependent manner. Adjusted RRs increased from 1.39 (1.17-1.64) for 1-14 cigarettes per day to 1.98 (1.57-2.36) for ≥25 cigarettes per day compared with nonsmokers with no exposure to passive smoke.

CONCLUSIONS

Our study suggests that exposure to passive smoke and active smoking are positively and independently associated with the risk of type 2 diabetes.

Caffeine intake, and the risk of stress, urgency and mixed urinary incontinence

PURPOSE

Although caffeine consumption is common and generally believed to affect bladder function, little is known about caffeine intake and incident urinary incontinence.

MATERIALS AND METHODS

We performed a prospective cohort study in 65,176 women 37 to 79 years old without incontinence in the Nurses' Health Study and the Nurses' Health Study II. Incident incontinence was identified from questionnaires during 4 years of followup. Caffeine intake was measured using food frequency questionnaires administered before incontinence development. The multivariate adjusted relative risk of the relation between caffeine intake and incontinence risk as well as attributable risk were calculated.

RESULTS

Caffeine was not associated with incontinence monthly or more. However, there was a modest, significantly increased risk of incontinence at least weekly in women with the highest (greater than 450 mg) vs the lowest (less than 150 mg) daily intake (RR 1.19, 95% CI 1.06-1.34) and a significant trend of increasing risk with increasing intake (p for trend = 0.01). This risk appeared focused on incident urgency incontinence (greater than 450 vs less than 150 mg daily, RR 1.34, 95% CI 1.00-1.80, p for trend = 0.05) but not on stress or mixed incontinence (p for trend = 0.75 and 0.19, respectively). The attributable risk of urgency incontinence associated with high caffeine intake was 25%.

CONCLUSIONS

Findings suggest that high but not lower caffeine intake is associated with a modest increase in the incidence of frequent urgency incontinence. A fourth of the cases with the highest caffeine consumption would be eliminated if high caffeine intake were eliminated. Confirmation of these findings in other studies is needed before recommendations can be made.

Factors related to colonization with Oxalobacter formigenes in U.S. adults

GOALS

To elucidate the determinants of Oxalobacter formigenes colonization in humans.

BACKGROUND

O. formigenes is a gram-negative anaerobic bacterium that colonizes the colon of a substantial proportion of the normal population and metabolizes dietary and endogenous oxalate. The bacterium has been associated with a large reduction in the odds of recurrent calcium oxalate kidney stones. Subjects were 240 healthy individuals from Massachusetts and North Carolina. O. formigenes was detected by culture of fecal swabs. Information on factors of interest was obtained by telephone interviews and self-administered questionnaires.

STUDY RESULTS

The overall prevalence of O. formigenes was 38%. Use of specific antibiotics previously thought to affect the bacterium was significantly related to colonization, with prevalences of 17%, 27%, and 36%, for those who had used these drugs <1, 1-5, and >5 years ago, compared with 55% in nonusers. There were no significant associations with demographic factors, nutrient intake, or medical history, although the prevalence appeared to increase somewhat with increasing oxalate consumption.

CONCLUSIONS

Some antibiotics markedly affect colonization with O. formigenes. Although no other factor was identified as having a material influence on the prevalence of the bacterium, there is much to learn about how an individual acquires the organism and which factors affect persistence of colonization.

Association of dietary patterns with albuminuria and kidney function decline in older white women: a subgroup analysis from the Nurses' Health Study

BACKGROUND

Dietary patterns have been linked to such chronic diseases as cardiovascular disease, but sparse data currently are available for associations between dietary patterns and microalbuminuria or kidney function decline.

STUDY DESIGN

Subgroup analysis from a prospective observational cohort study.

SETTING & PARTICIPANTS

Female participants in the Nurses' Health Study who had dietary pattern data from food frequency questionnaires returned in 1984, 1986, 1990, 1994, and 1998 and urinary albumin-creatinine ratios from 2000 (n = 3,121); estimated glomerular filtration rate (eGFR) change between 1989 and 2000 was available for 3,071.

PREDICTOR

Prudent (higher intake of fruits, vegetables, legumes, fish, poultry, and whole grains), Western (higher intake of red and processed meats, saturated fats, and sweets), and Dietary Approach to Stop Hypertension (DASH)-style dietary patterns (also greater intake of vegetables, fruits, and whole grains).

OUTCOMES & MEASUREMENTS

Microalbuminuria (albumin-creatinine ratio, 25-354 μg/mg) in 2000 and change in kidney function using eGFR between 1989 and 2000.

RESULTS

After multivariable adjustment, the highest quartile of Western pattern score compared with the lowest quartile was associated directly with microalbuminuria (OR, 2.17; 95% CI, 1.18-3.66; P for trend = 0.01) and rapid eGFR decline ≥3 mL/min/1.73 m(2)/y (OR, 1.77; 95% CI, 1.03-3.03). Women in the top quartile of the DASH score had decreased risk of rapid eGFR decline (OR, 0.55; 95% CI, 0.38-0.80), but no association with microalbuminuria. These associations did not vary by diabetes status. The prudent dietary pattern was not associated with microalbuminuria or eGFR decline.

LIMITATIONS

Study cohort included primarily older white women and generalizability of results would benefit from validation in nonwhites and men.

CONCLUSIONS

A Western dietary pattern is associated with a significantly increased odds of microalbuminuria and rapid kidney function decrease, whereas a DASH-style dietary pattern may be protective against rapid eGFR decline.

Mortality associated with low serum sodium concentration in maintenance hemodialysis

BACKGROUND

low serum sodium concentrations are associated with an increased risk of death in the general population, but causality is uncertain due to confounding from clinical conditions such as congestive heart failure and cirrhosis, in which hyponatremia results from elevated levels of arginine vasopressin.

METHODS

to examine the association between predialysis serum sodium concentration and mortality in patients undergoing hemodialysis for end-stage renal disease, a condition in which arginine vasopressin does not affect water excretion and osmoregulation, we studied 1549 oligoanuric participants in the HEMO study, a randomized controlled trial of hemodialysis patients examining the effect of hemodialysis dose and flux. We used proportional hazards models to compare the risk of death according to predialysis serum sodium concentration.

RESULTS

considered as a continuous variable, each 4-mEq/L increment in baseline predialysis serum sodium concentration was associated with a hazard ratio for all-cause mortality of 0.84 (95% confidence interval (CI), 0.78-0.90). Multivariable adjustment for demographic, clinical, laboratory, and dialysis-specific covariates, including ultrafiltration volume, did not appreciably change the results (hazard ratio for all-cause mortality of 0.89; 95% CI, 0.82-0.96). the results also were consistent in time-updated analyses using repeated measures of serum sodium and other relevant covariates.

CONCLUSION

Lower predialysis serum sodium concentration is associated with an increased risk of death. Considering the unique physiology in the dialysis population, these findings raise the possibility that hyponatremia itself may be a causal determinant of mortality in the broader population.

Prescribed dietary phosphate restriction and survival among hemodialysis patients

BACKGROUND AND OBJECTIVES

Hyperphosphatemia is common among hemodialysis patients. Although prescribed dietary phosphate restriction is a recommended therapy, little is known about the long-term effects on survival.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a post hoc analysis of data from the Hemodialysis Study (n = 1751). Prescribed dietary phosphate was recorded at baseline and annually thereafter. Marginal structural proportional hazard models were fit to estimate the adjusted association between dietary phosphate restriction and mortality in the setting of time-dependent confounding.

RESULTS

At baseline, prescribed daily phosphate was restricted to levels ≤ 870, 871 to 999, 1000, 1001 to 2000 mg, and not restricted in 300, 314, 307, 297, and 533 participants, respectively. More restrictive prescribed dietary phosphate was associated with poorer indices of nutritional status on baseline analyses and a persistently greater need for nutritional supplementation but not longitudinal changes in caloric or protein intake. On marginal structural analysis, there was a stepwise trend toward greater survival with more liberal phosphate prescription, which reached statistical significance among subjects prescribed 1001 to 2000 mg/d and those with no specified phosphate restriction: hazard ratios (95% CIs) 0.73 (0.54 to 0.97) and 0.71 (0.55 to 0.92), respectively. Subgroup analysis suggested a more pronounced survival benefit of liberal dietary phosphate prescription among nonblacks, participants without hyperphosphatemia, and those not receiving activated vitamin D.

CONCLUSIONS

Prescribed dietary phosphate restriction is not associated with improved survival among prevalent hemodialysis patients, and increased level of restriction may be associated with greater mortality particularly in some subgroups.

Associations of sugar and artificially sweetened soda with albuminuria and kidney function decline in women

BACKGROUND AND OBJECTIVES

Sugar-sweetened soda is reported to be associated with increased risk for diabetes and albuminuria, but there are currently limited data on how sugar or artificially sweetened soda may be related to kidney function decline.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study identified 3318 women participating in the Nurses' Health Study with data on soda intake and albuminuria; of these, 3256 also had data on estimated GFR (eGFR) change between 1989 and 2000. Cumulative average beverage intake was derived from the 1984, 1986, 1990, 1994, and 1998 food frequency questionnaires. Serving categories included <1/mo (referent), 1 to 4/mo, 2 to 6/wk, 1 to 1.9/d, and ≥ 2/d. Microalbuminuria (MA) was considered a urinary albumin-to-creatinine ratio of 25 to 355 μg/mg. For kidney function change, the primary outcome was a ≥ 30% decline in eGFR over 11 years; rapid eGFR decline defined as ≥ 3 ml/min per 1.73 m(2) per year was also examined.

RESULTS

Consumption of ≥ 2 servings per day of artificially sweetened (diet) soda was independently associated with eGFR decline ≥ 30% (OR 2.02, 95% CI 1.36 to 3.01) and ≥ 3 ml/min per 1.73 m(2) per year (OR 2.20, 95% CI 1.36 to 3.55). No increased risk for eGFR decline was observed for <2 servings per day of diet soda. No associations were noted between diet soda and MA or sugar soda and MA or eGFR decline.

CONCLUSIONS

Consumption of ≥ 2 servings per day of artificially sweetened soda is associated with a 2-fold increased odds for kidney function decline in women.

Insulin resistance and risk of incident hypertension among men

J Clin Hypertens (Greenwich). 2009;11:483-490. (c) 2009 Wiley Periodicals, Inc.The independent association between insulin resistance and the development of hypertension remains in doubt because insulin resistance correlates with other metabolic factors also proposed to be associated with hypertension. The authors examined the association between the insulin sensitivity index and incident hypertension in a prospective nested case-control study among 1453 men (mean age, 61 years) who participated in the Health Professionals' Follow-up Study. The authors computed the insulin sensitivity index for each man in the study based on fasting insulin and triglyceride levels. Logistic regression was performed conditioned on age and adjusted for standard hypertension risk factors as well as renal function, cholesterol, and uric acid. The insulin sensitivity index was 6% lower in the cases compared with the controls (P<.001). The multivariable odds ratio for hypertension comparing the lowest with highest quartile of insulin sensitivity index was 1.09 (0.71-1.65) among the entire sample. However, the association between the insulin sensitivity index and incident hypertension differed significantly by age (P interaction <.001). Among men younger than 60 years, the multivariable odds ratio for the lowest compared with highest quartile was 1.93 (1.01-3.71) but was 0.67 (0.37-1.24) among older men. Insulin resistance is independently associated with incident hypertension among younger men.

Choice of vascular access among incident hemodialysis patients: a decision and cost-utility analysis

BACKGROUND AND OBJECTIVES

Arteriovenous fistulas (AVFs) are widely accepted as the preferred hemodialysis vascular access type. However, supporting data have failed to consider morbidity and mortality incurred during failed creation attempts and may therefore overstate potential advantages. This study compares survival, quality-adjusted survival, and costs among incident hemodialysis patients after attempted placement of AVFs or arteriovenous grafts (AVGs).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Analogous Markov models were created, one each for AVF and AVG. Patients entered consideration at the time of first access creation, contemporaneous with dialysis initiation. Subsequent outcomes were determined probabilistically; transition probabilities, utilities, and costs were gathered from published sources. To ensure comparability between AVFs and AVGs, the timing and likelihood of access maturation were measured in a contemporary cohort of incident hemodialysis patients.

RESULTS

Mean (SD) overall survival was 39.2 (0.8) and 36.7 (1.0) months for AVFs and AVGs, respectively: difference (95% confidence interval [CI]) 2.6 (1.8, 3.3) months. Quality-adjusted survival was 36.1 (0.8) and 32.5 (0.9) quality-adjusted life months (QALMs) for AVFs and AVGs, respectively: difference (95% CI) 3.6 (2.8, 4.3) QALMs. The incremental cost-effectiveness ratio (95% CI) for AVFs relative to AVGs was $446 (-6023, 6994) per quality-adjusted life year saved.

CONCLUSIONS

AVFs are associated with greater overall and quality-adjusted survival than AVGs. Observed differences were much less pronounced than might be expected from existing literature, suggesting that prospective identification of patients at high risk for AVF maturational failure might enable improvements in health outcomes via individualization of access planning.

DASH-style diet and 24-hour urine composition

BACKGROUND AND OBJECTIVES

We previously observed associations between a Dietary Approaches to Stop Hypertension (DASH)-style diet and large reductions in kidney stone risk. This study examined associations between a DASH-style diet and 24-hour excretions of urinary lithogenic factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 3426 participants with and without nephrolithiasis in the Health Professionals Follow-up Study (HPFS) and the Nurses' Health Studies (NHS) I and II. A dietary DASH score was based on seven components: high intake of fruits, vegetables, nuts and legumes, dairy products, and whole grains and low intake of sweetened beverages and red and processed meats. We used analysis of covariance to adjust for age, stone history, body size, and other factors.

RESULTS

Comparing participants in the highest to lowest quintiles of DASH score, multivariate-adjusted urinary calcium excretion was 3% greater in HPFS (P trend 0.12), 10% greater in NHS I (P trend <0.01), and 12% greater in NHS II (P trend 0.05). Urinary oxalate was 4% to 18% greater (P trend all ≤0.03), urinary citrate was 11% to 16% greater (P trend all <0.01), and urinary volume was 16% to 32% greater (P trend all <0.001). Higher DASH score was associated with higher urine potassium, magnesium, phosphate, and pH, and lower relative supersaturations (RSS) of calcium oxalate (women only) and uric acid.

CONCLUSIONS

A DASH-style diet may reduce stone risk by increasing urinary citrate and volume. The small associations between higher DASH score and lower RSS suggest unidentified stone inhibitors in dairy products and/or plants.

Determinants of plasma parathyroid hormone levels in young women

While the effects of calcium, phosphorus intake, and vitamin D on parathyroid hormone (PTH) have been well studied, less is known about other factors that impact PTH. Our goal was to delineate associations between demographic, dietary, and plasma factors and PTH. We conducted a cross-sectional study of intact PTH among 1,288 nonblack women in the Nurses Health Study II aged 33-53 with BMI <30 kg/m2 and eGFR > or = 60 ml/min/1.73 m2. Median PTH was 30.7 pg/ml. After adjusting for 25-hydroxyvitamin D and other factors, PTH was 4.1 pg/ml lower (95% CI -7.7 to -0.5) in women who smoked 1-14 cigarettes/day and 6.4 pg/ml lower (95% CI -11.2 to -1.7) in women who smoked >15 cigarettes/day compared to nonsmokers. After multivariate adjustment, women whose BMI was 27-29 kg/m2 had PTH levels 2.0 pg/ml higher (95% CI 0.2-3.9) compared to BMI of 21-22 kg/m2 and women in the highest quartile of plasma phosphorus had PTH levels 4.1 pg/ml lower (95% CI -5.8 to -2.4) than women in the lowest quartile. Higher vitamin A intake was independently associated with lower PTH, whereas lower calcium intake, lower plasma calcium, lower plasma 25-hydroxyvitamin D, and winter blood draw were associated with higher PTH. Intakes of phosphorus, animal protein, magnesium, alcohol, and caffeine were not associated with PTH. Factors not classically associated with calcium-phosphorus metabolism impact PTH. Additional research is needed to elucidate the mechanisms whereby smoking, vitamin A, and phosphorus affect PTH and to examine how body size and season may affect PTH independent of 25(OH)D.

A prospective study of cardiovascular risk factors and incident hearing loss in men

OBJECTIVES/HYPOTHESIS

Hearing loss is the most common sensory disorder in the United States, affecting more than 36 million people. Cardiovascular risk factors have been associated with the risk of hearing loss in cross-sectional studies, but prospective data are currently lacking.

STUDY DESIGN

Prospective cohort study.

METHODS

We prospectively evaluated the association between diagnosis of hypertension, diabetes mellitus, hypercholesterolemia, smoking, or body mass index (BMI) and incident hearing loss. Participants were 26,917 men in the Health Professionals Follow-up Study, aged 40 to 74 years at baseline in 1986. Study participants completed questionnaires about lifestyle and medical history every 2 years. Information on self-reported professionally diagnosed hearing loss and year of diagnosis was obtained from the 2004 questionnaire, and cases were defined as hearing loss diagnosed between 1986 and 2004. Multivariable-adjusted hazard ratios (HRs) were calculated using Cox proportional hazards regression models.

RESULTS

A total of 3,488 cases of hearing loss were identified. History of hypertension (HR 0.96; 95% confidence interval [CI], 0.88-1.03), diabetes mellitus (HR 0.92; 95% CI, 0.78-1.08), or obesity (HR 1.02; 95% CI, 0.90-1.15 for BMI >or=30 compared to normal range of 19-24.9) was not significantly associated with hearing-loss risk. Hypercholesterolemia (HR 1.10; 95% CI, 1.02-1.18) and past smoking history (HR 1.09; 95% CI, 1.01-1.17) were associated with a significantly increased risk of hearing loss after multivariate adjustment.

CONCLUSIONS

A history of hypertension, diabetes mellitus, or obesity is not associated with increased risk of hearing loss; a history of past smoking or hypercholesterolemia has a small but statistically significant association with increased risk of hearing loss in adult males.

Change in prevalence of hearing loss in US adolescents

CONTEXT

Hearing loss is common and, in young persons, can compromise social development, communication skills, and educational achievement.

OBJECTIVE

To examine the current prevalence of hearing loss in US adolescents and determine whether it has changed over time.

DESIGN

Cross-sectional analyses of US representative demographic and audiometric data from the 1988 through 1994 and 2005 through 2006 time periods.

SETTING

The Third National Health and Nutrition Examination Survey (NHANES III), 1988-1994, and NHANES 2005-2006.

PARTICIPANTS

NHANES III examined 2928 participants and NHANES 2005-2006 examined 1771 participants, aged 12 to 19 years.

MAIN OUTCOME MEASURES

We calculated the prevalence of hearing loss in participants aged 12 to 19 years after accounting for the complex survey design. Audiometrically determined hearing loss was categorized as either unilateral or bilateral for low frequency (0.5, 1, and 2 kHz) or high frequency (3, 4, 6, and 8 kHz), and as slight loss (> 15 to < 25 dB) or mild or greater loss (> or = 25 dB) according to hearing sensitivity in the worse ear. The prevalence of hearing loss from NHANES 2005-2006 was compared with the prevalence from NHANES III (1988-1994). We also examined the cross-sectional relations between several potential risk factors and hearing loss. Logistic regression was used to calculate multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The prevalence of any hearing loss increased significantly from 14.9% (95% CI, 13.0%-16.9%) in 1988-1994 to 19.5% (95% CI, 15.2%-23.8%) in 2005-2006 (P = .02). In 2005-2006, hearing loss was more commonly unilateral (prevalence, 14.0%; 95% CI, 10.4%-17.6%, vs 11.1%; 95% CI, 9.5%-12.8% in 1988-1994; P = .005) and involved the high frequencies (prevalence, 16.4%; 95% CI, 13.2%-19.7%, vs 12.8%; 95% CI, 11.1%-14.5% in 1988-1994; P = .02). Individuals from families below the federal poverty threshold (prevalence, 23.6%; 95% CI, 18.5%-28.7%) had significantly higher odds of hearing loss (multivariate adjusted OR, 1.60; 95% CI, 1.10-2.32) than those above the threshold (prevalence, 18.4%; 95% CI, 13.6%-23.2%).

CONCLUSION

The prevalence of hearing loss among a sample of US adolescents aged 12 to 19 years was greater in 2005-2006 compared with 1988-1994.

Urinary biomarkers for sensitive and specific detection of acute kidney injury in humans

Acute kidney injury (AKI) is associated with high morbidity and mortality. The lack of sensitive and specific injury biomarkers has greatly impeded the development of therapeutic strategies to improve outcomes of AKI.The unique objective of this study was to evaluate the diagnostic performance of nine urinary biomarkers of AKI-kidney injury molecule-1 (KIM-1), neutrophil gelatinase associated lipocalin (NGAL), interleukin-18 (IL-18), hepatocyte growth factor (HGF), cystatin C (Cys), N-acetyl-beta-D-glucosaminidase (NAG), vascular endothelial growth factor (VEGF), chemokine interferon-inducible protein 10 (IP-10; CXCL10), and total protein-in a cross-sectional comparison of 204 patients with or without AKI.Median urinary concentrations of each biomarker were significantly higher in patients with AKI than in those without AKI (p < 0.001). The area under the receiver operating characteristics curve (AUC-ROC) for the combination of biomarkers using a logic regression model [risk score of 2.93*(NGAL > 5.72 and HGF > 0.17) + 2.93*(PROTEIN > 0.22) -2*(KIM < 0.58)] was greater (0.94) than individual biomarker AUC-ROCs. Age-adjusted levels of urinary KIM-1, NAG, HGF, VEGF, and total protein were significantly higher in patients who died or required renal replacement therapy (RRT) when compared to those who survived and did not require RRT.Our results demonstrate the comparative value of multiple biomarkers in the diagnosis and prognosis of AKI.

Prevalence and characteristics of tinnitus among US adults

BACKGROUND

Tinnitus is common; however, few risk factors for tinnitus are known.

METHODS

We examined cross-sectional relations between several potential risk factors and self-reported tinnitus in 14,178 participants in the 1999-2004 National Health and Nutrition Examination Surveys, a nationally representative database. We calculated the prevalence of any and frequent (at least daily) tinnitus in the overall US population and among subgroups. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) after adjusting for multiple potential confounders.

RESULTS

Approximately 50 million US adults reported having any tinnitus, and 16 million US adults reported having frequent tinnitus in the past year. The prevalence of frequent tinnitus increased with increasing age, peaking at 14.3% between 60 and 69 years of age. Non-Hispanic whites had higher odds of frequent tinnitus compared with other racial/ethnic groups. Hypertension and former smoking were associated with an increase in odds of frequent tinnitus. Loud leisure-time, firearm, and occupational noise exposure also were associated with increased odds of frequent tinnitus. Among participants who had an audiogram, frequent tinnitus was associated with low-mid frequency (OR 2.37; 95% CI, 1.76-3.21) and high frequency (OR 3.00; 95% CI, 1.78-5.04) hearing impairment. Among participants who were tested for mental health conditions, frequent tinnitus was associated with generalized anxiety disorder (OR 6.07; 95% CI, 2.33-15.78) but not major depressive disorder (OR 1.58; 95% CI, 0.54-4.62).

CONCLUSIONS

The prevalence of frequent tinnitus is highest among older adults, non-Hispanic whites, former smokers, and adults with hypertension, hearing impairment, loud noise exposure, or generalized anxiety disorder. Prospective studies of risk factors for tinnitus are needed.

Associations of diet with albuminuria and kidney function decline

BACKGROUND AND OBJECTIVES

Sparse longitudinal data exist on how diet influences microalbuminuria and estimated GFR (eGFR) decline in people with well-preserved kidney function.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

Of the 3348 women participating in the Nurses' Health Study who had data on urinary albumin to creatinine ratio in 2000, 3296 also had data on eGFR change between 1989 and 2000. Cumulative average intake of nutrients over 14 years was derived from semiquantitative food frequency questionnaires answered in 1984, 1986, 1990, 1994, and 1998. Microalbuminuria presence and eGFR decline > or = 30% were the outcomes of interest.

RESULTS

Compared with the lowest quartile, the highest quartile of animal fat (odds ratio (OR): 1.72; 95% confidence interval (CI): 1.12 to 2.64) and two or more servings of red meat per week (OR: 1.51; 95% CI: 1.01 to 2.26) were directly associated with microalbuminuria. After adjustment for other nutrients individually associated with eGFR decline > or = 30%, only the highest quartile of sodium intake remained directly associated (OR: 1.52; 95% CI: 1.10 to 2.09), whereas beta-carotene appeared protective (OR: 0.62, 95% CI: 0.43 to 0.89). Results did not vary by diabetes status for microalbuminuria and eGFR outcomes or in those without hypertension at baseline for eGFR decline. No significant associations were seen for other types of protein, fat, vitamins, folate, fructose, or potassium.

CONCLUSIONS

Higher dietary intake of animal fat and two or more servings per week of red meat may increase risk for microalbuminuria. Lower sodium and higher beta-carotene intake may reduce risk for eGFR decline.

New loci associated with kidney function and chronic kidney disease

Chronic kidney disease (CKD) is a significant public health problem, and recent genetic studies have identified common CKD susceptibility variants. The CKDGen consortium performed a meta-analysis of genome-wide association data in 67,093 individuals of European ancestry from 20 predominantly population-based studies in order to identify new susceptibility loci for reduced renal function as estimated by serum creatinine (eGFRcrea), serum cystatin c (eGFRcys) and CKD (eGFRcrea < 60 ml/min/1.73 m(2); n = 5,807 individuals with CKD (cases)). Follow-up of the 23 new genome-wide-significant loci (P < 5 x 10(-8)) in 22,982 replication samples identified 13 new loci affecting renal function and CKD (in or near LASS2, GCKR, ALMS1, TFDP2, DAB2, SLC34A1, VEGFA, PRKAG2, PIP5K1B, ATXN2, DACH1, UBE2Q2 and SLC7A9) and 7 loci suspected to affect creatinine production and secretion (CPS1, SLC22A2, TMEM60, WDR37, SLC6A13, WDR72 and BCAS3). These results further our understanding of the biologic mechanisms of kidney function by identifying loci that potentially influence nephrogenesis, podocyte function, angiogenesis, solute transport and metabolic functions of the kidney.

Plasma resistin levels associate with risk for hypertension among nondiabetic women

Emerging evidence suggests a role for resistin in inflammation and vascular dysfunction, which may contribute to the pathogenesis of hypertension, but the association between resistin levels and incident hypertension is unknown. We examined the association between plasma resistin levels and the risk for incident hypertension among 872 women without a history of hypertension or diabetes from the Nurses' Health Study. We identified 361 incident cases of hypertension during 14 years of follow-up. After adjustment for potential confounders, resistin levels in the highest tertile conferred a 75% higher risk for hypertension than the lowest tertile (relative risk [RR] 1.75; 95% confidence interval [CI] 1.19 to 2.56). Further adjustment for other adipokines did not change the RR substantially. In stratified analysis, resistin levels in the highest tertile significantly increased the risk for hypertension among women aged >or=55 years (adjusted RR 2.40; 95% CI 1.55 to 3.73) but not among women aged <55 years (adjusted RR 0.64; 95% CI 0.25 to 1.62). In a subset analysis of 362 women who also had measurements of inflammatory and endothelial biomarkers, plasma resistin levels significantly correlated with IL-6, soluble TNF receptor 2, intercellular adhesion molecule 1, vascular adhesion molecule 1, and E-selectin after controlling for age and body mass index. After further adjustment for these biomarkers and C-reactive protein, resistin levels remained significantly associated with incident hypertension. In conclusion, higher plasma resistin levels independently associate with an increased risk for incident hypertension among women without diabetes.

The incidence of urinary incontinence across Asian, black, and white women in the United States

OBJECTIVE

We calculated incidence rates of urinary incontinence by incontinence frequency and type over 4 years in Asian, black, and white women in the United States.

STUDY DESIGN

Prospective analyses included 76,724 participants aged 37-79 years in the Nurses' Health Study cohorts with no incontinence at baseline.

RESULTS

The 4-year incidence of incontinence at least monthly was higher in white women (7.3/100 person-years) compared with Asian (5.7/100 person-years; P = .003) and black women (4.8/100 person-years; P < .001). The incidence of at least weekly stress incontinence was significantly lower in black compared with white women (0.1 vs 0.8 per 100 person-years; P < .001). The difference between black and white women in the incidence of any incontinence and stress incontinence remained significant after adjusting for known risk factors (P < .001 for both).

CONCLUSION

Urinary incontinence incidence differs by race. Studies to confirm these results and better understand underlying mechanisms are needed.

A prospective study of vitamin intake and the risk of hearing loss in men

OBJECTIVE

Hearing loss is the most common sensory disorder in the United States, afflicting more than 36 million people. Higher intakes of vitamins C, E, beta carotene, B12, and folate have been proposed to reduce the risk of hearing loss.

STUDY DESIGN

We prospectively evaluated the association between intake from foods and supplements of vitamins C, E, beta carotene, B12, and folate, and the incidence of hearing loss.

SETTING

Health Professionals Follow-up Study.

SUBJECTS AND METHODS

A total of 26,273 men aged 40 to 74 years at baseline in 1986. Participants completed questionnaires about lifestyle and medical history every two years and diet every four years. Information on self-reported professionally diagnosed hearing loss and year of diagnosis was obtained from the 2004 questionnaire, and cases were defined as hearing loss diagnosed between 1986 and 2004. Cox proportional hazards multivariate regression was used to adjust for potential confounders.

RESULTS

There were 3559 cases of hearing loss identified. Overall, there was no significant association between vitamin intake and risk of hearing loss. Among men aged > or =60 years, total folate intake was associated with a reduced risk of hearing loss; the relative risk for men aged > or =60 years old in the highest quintile compared with the lowest quintile of folate intake was 0.79 (95% confidence interval 0.65-0.96).

CONCLUSIONS

Higher intake of vitamin C, E, beta carotene, or B12 does not reduce the risk of hearing loss in adult males. Men aged > or =60 years may benefit from higher folate intake to reduce the risk of developing hearing loss.

Analgesic use and the risk of hearing loss in men

BACKGROUND

Hearing loss is a common sensory disorder, yet prospective data on potentially modifiable risk factors are limited. Regularly used analgesics, the most commonly used drugs in the US, may be ototoxic and contribute to hearing loss.

METHODS

We examined the independent association between self-reported professionally diagnosed hearing loss and regular use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen in 26,917 men aged 40-74 years at baseline in 1986. Study participants completed detailed questionnaires at baseline and every 2 years thereafter. Incident cases of new-onset hearing loss were defined as those diagnosed after 1986. Cox proportional hazards multivariate regression was used to adjust for potential confounding factors.

RESULTS

During 369,079 person-years of follow-up, 3488 incident cases of hearing loss were reported. Regular use of each analgesic was independently associated with an increased risk of hearing loss. Multivariate-adjusted hazard ratios of hearing loss in regular users (2+ times/week) compared with men who used the specified analgesic <2 times/week were 1.12 (95% confidence interval [CI], 1.04-1.20) for aspirin, 1.21 (95% CI, 1.11-1.33) for NSAIDs, and 1.22 (95% CI, 1.07-1.39) for acetaminophen. For NSAIDs and acetaminophen, the risk increased with longer duration of regular use. The magnitude of the association was substantially higher in younger men. For men younger than age 50 years, the hazard ratio for hearing loss was 1.33 for regular aspirin use, 1.61 for NSAIDs, and 1.99 for acetaminophen.

CONCLUSIONS

Regular use of aspirin, NSAIDs, or acetaminophen increases the risk of hearing loss in men, and the impact is larger on younger individuals.

Physical activity and albuminuria

Higher urinary albumin excretion predicts future cardiovascular disease, hypertension, and chronic kidney disease. Physical activity improves endothelial function so activity may reduce albuminuria. Among diabetics, physical activity decreases albuminuria. In nondiabetics, prior studies have shown no association. The authors explored the cross-sectional association between physical activity and albuminuria in 3,587 nondiabetic women in 2 US cohorts, the Nurses' Health Study I in 2000 and the Nurses' Health Study II in 1997. Physical activity was expressed as metabolic equivalents per week. The outcome was the top albumin/creatinine ratio (ACR) decile. Multivariate logistic regression was used. Secondary analyses explored the ACR association with strenuous activity and walking. The mean age was 58.6 years. Compared with women in the lowest physical activity quintile, those in the highest quintile had a multivariate-adjusted odds ratio for the top ACR decile of 0.65 (95% confidence interval (CI): 0.46, 0.93). The multivariate-adjusted odds ratio for the top ACR decile for those with greater than 210 minutes per week of strenuous activity compared with no strenuous activity was 0.61 (95% CI: 0.37, 0.99), and for those in the highest quintile of walking compared with the lowest quintile, it was 0.69 (95% CI: 0.47, 1.02). Greater physical activity is associated with a lower ACR in nondiabetic women.

Physical activity and the risk of community-acquired pneumonia in US women

BACKGROUND

Exercise bolsters the immune system and can prevent various infections in certain populations. However, limited data exist regarding the role of physical activity and the risk of community-acquired pneumonia.

METHODS

During a 12-year period, we prospectively examined the association between physical activity and the risk of community-acquired pneumonia among 83,165 women in the Nurses' Health Study II who were between the ages of 27 and 44 years in 1991. We excluded women who had pneumonia before 1991 and those with a history of cancer, cardiovascular disease, or asthma. Biennial self-administered mailed questionnaires were used to determine activity level. Cases of pneumonia required a diagnosis by a physician and confirmation with a chest radiograph.

RESULTS

We identified 1265 new cases of community-acquired pneumonia during 965,168 person-years of follow up. After adjusting for age, women in the highest quintile of physical activity were less likely to develop pneumonia than women in the lowest quintile (relative risk [RR] = 0.72; 95% confidence interval [CI], 0.60-0.86; P for trend<.001). However, the association was attenuated and only marginally significant after further adjusting for body mass index, smoking, and alcohol use (RR=0.84; 95% CI, 0.70-1.01; P for trend=.06). Women in the highest quintile of walking were less likely to develop pneumonia compared with women who walked the least (multivariate adjusted RR=0.82; 95% CI, 0.69-0.98); however, the trend across quintiles was not significant (P for trend=.25).

CONCLUSION

Higher physical activity does not substantially reduce pneumonia risk in well-nourished women.

Lipid and inflammatory biomarkers and kidney function decline in type 2 diabetes

AIMS/HYPOTHESIS

Potentially modifiable biomarkers may influence the decline in estimated GFR (eGFR), but few data are currently available in type 2 diabetic adults.

METHODS

We studied 516 women with type 2 diabetes in the Nurses' Health Study with data on lipid and inflammatory biomarkers from plasma collected in 1989 and plasma creatinine in samples collected in 1989 and 2000. An estimated GFR decline of >or=25% over 11 years was the outcome of interest.

RESULTS

Comparing the highest with the lowest quartile, soluble tumour necrosis factor receptor 2 (sTNFR-2) was independently associated with an eGFR decline of >or=25% (multivariate OR 5.81; 95% CI 2.90-11.65); this association was stronger in obese women (OR 16.76; 95% CI 4.69-59.90 for BMI >or=30 kg/m(2); OR 2.78, 95% CI 1.12-6.89 for BMI <30 kg/m(2); p for interaction = 0.02). No lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, non-HDL-cholesterol, triacylglycerols, lipoprotein(a), or apolipoprotein B) or other markers of inflammation (C-reactive protein, fibrinogen, E-selectin, intracellular cell adhesion molecule 1, leptin or adiponectin) were significantly associated with eGFR decline after multivariable adjustment.

CONCLUSIONS/INTERPRETATION

Elevated sTNFR-2 levels may be an important and potentially modifiable risk factor for eGFR decline in type 2 diabetes, especially in those with a BMI of >or=30 kg/m(2).

CRP gene variation and risk of community-acquired pneumonia

BACKGROUND AND OBJECTIVE

CRP has several potentially antibacterial effects, and variation in the CRP gene is known to influence CRP levels. Whether this variation influences risk of infection, and hence whether CRP has anti-infective activity in humans, is uncertain.

METHODS

We evaluated a series of haplotype-tagging single nucleotide polymorphisms among 5374 individuals in the Cardiovascular Health Study, a cohort of older adults from four communities, who were followed for community-acquired pneumonia for 12-13 years. Secondarily, we evaluated whether these polymorphisms varied among men in the Health Professionals Follow-up Study who self-reported pneumonia on biennial questionnaires.

RESULTS

There were 581 (507 white and 74 black) Cardiovascular Health Study participants with incident hospitalizations for pneumonia. No single nucleotide polymorphism or haplotypes were associated with risk among white Cardiovascular Health Study participants. Among black participants, the haplotype tagged by A790T was associated with lower risk of incident pneumonia (hazard ratio 0.5; 95% confidence interval: 0.3-0.9) and with higher CRP levels. In Health Professionals Follow-up Study, a separate haplotype was associated with less frequent self-reported pneumonia but not with circulating CRP levels.

CONCLUSIONS

Some genetic variants in CRP may be associated with risk of pneumonia, but haplotypes associated with risk are variably associated with baseline CRP levels. If CRP is a relevant component of innate immunity in humans, the inducibility or tissue-specificity of expression may be at least as important as chronic circulating levels.

Demographic, dietary, and urinary factors and 24-h urinary calcium excretion

BACKGROUND AND OBJECTIVES

Higher urinary calcium is a risk factor for nephrolithiasis. This study delineated associations between demographic, dietary, and urinary factors and 24-h urinary calcium.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Cross-sectional studies were conducted of 2201 stone formers (SF) and 1167 nonstone formers (NSF) in the Health Professionals Follow-up Study (men) and Nurses' Health Studies I and II (older and younger women).

RESULTS

Median urinary calcium was 182 mg/d in men, 182 mg/d in older women, and 192 mg/d in younger women. Compared with NSF, urinary calcium as a fraction of calcium intake was 33 to 38% higher in SF (P values < or =0.01). In regression analyses, participants were combined because associations with urinary calcium were similar in each cohort and in SF and NSF. After multivariate adjustment, participants in the highest quartile of calcium intake excreted 18 mg/d more urinary calcium than those in the lowest (P trend =0.01). Caffeine and family history of nephrolithiasis were positively associated, whereas urinary potassium, thiazides, gout, and age were inversely associated, with urinary calcium. After multivariate adjustment, participants in the highest quartiles of urinary magnesium, sodium, sulfate, citrate, phosphorus, and volume excreted 71 mg/d, 37 mg/d, 44 mg/d, 61 mg/d, 37 mg/d, and 24 mg/d more urinary calcium, respectively, than participants in the lowest (P values trend < or =0.01).

CONCLUSIONS

Intestinal calcium absorption and/or negative calcium balance is greater in SF than NSF. Higher calcium intakes at levels typically observed in free-living individuals are associated with only small increases in urinary calcium.

Mortality after hospitalization with mild, moderate, and severe hyponatremia

BACKGROUND

Hyponatremia is the most common electrolyte abnormality in hospitalized individuals.

METHODS

To investigate the association between serum sodium concentration and mortality, we conducted a prospective cohort study of 98,411 adults hospitalized between 2000 and 2003 at 2 teaching hospitals in Boston, Massachusetts. The main outcome measures were in-hospital, 1-year, and 5-year mortality. Multivariable logistic regression and Cox proportional hazards models were used to compare outcomes in patients with varying degrees of hyponatremia against those with normal serum sodium concentration.

RESULTS

Hyponatremia (serum sodium concentration <135 mEq/L) was observed in 14.5% of patients on initial measurement. Compared with patients with normonatremia (135-144 mEq/L), those with hyponatremia were older (67.0 vs 63.1 years, P <.001) and had more comorbid conditions (mean Deyo-Charlson Index 1.9 vs 1.4, P <.001). In multivariable-adjusted models, patients with hyponatremia had an increased risk of death in hospital (odds ratio 1.47, 95% confidence interval [CI], 1.33-1.62), at 1 year (hazard ratio 1.38, 95% CI, 1.32-1.46), and at 5 years (hazard ratio 1.25, 95% CI, 1.21-1.30). The increased risk of death was evident even in those with mild hyponatremia (130-134 mEq/L; odds ratio 1.37, 95% CI, 1.23-1.52). The relationship between hyponatremia and mortality was pronounced in patients admitted with cardiovascular disease, metastatic cancer, and those admitted for procedures related to the musculoskeletal system. Resolution of hyponatremia during hospitalization attenuated the increased mortality risk conferred by hyponatremia.

CONCLUSION

Hyponatremia, even when mild, is associated with increased mortality.

DASH-style diet associates with reduced risk for kidney stones

The impact of the Dietary Approaches to Stop Hypertension (DASH) diet on kidney stone formation is unknown. We prospectively examined the relation between a DASH-style diet and incident kidney stones in the Health Professionals Follow-up Study (n = 45,821 men; 18 yr of follow-up), Nurses' Health Study I (n = 94,108 older women; 18 yr of follow-up), and Nurses' Health Study II (n = 101,837 younger women; 14 yr of follow-up). We constructed a DASH score based on eight components: high intake of fruits, vegetables, nuts and legumes, low-fat dairy products, and whole grains and low intake of sodium, sweetened beverages, and red and processed meats. We used Cox hazards regression to adjust for factors that included age, BMI, and fluid intake. Over a combined 50 yr of follow-up, we documented 5645 incident kidney stones. Participants with higher DASH scores had higher intakes of calcium, potassium, magnesium, oxalate, and vitamin C and had lower intakes of sodium. For participants in the highest compared with the lowest quintile of DASH score, the multivariate relative risks for kidney stones were 0.55 (95% CI, 0.46 to 0.65) for men, 0.58 (95% CI, 0.49 to 0.68) for older women, and 0.60 (95% CI, 0.52 to 0.70) for younger women. Higher DASH scores were associated with reduced risk even in participants with lower calcium intake. Exclusion of participants with hypertension did not change the results. In conclusion, consumption of a DASH-style diet is associated with a marked decrease in kidney stone risk.

Diet-dependent net acid load and risk of incident hypertension in United States women

Animal and human studies suggest a potential link between acid-base status and blood pressure. Contemporary Western diets yield a daily systemic acid load of varying amounts, yet the association with hypertension has never been explored. We prospectively examined the association between the diet-dependent net acid load (also known as the estimated net endogenous acid production) and the risk of incident hypertension among 87 293 women without a history of hypertension in the Nurses' Health Study II. We also used the ratio of animal protein intake to potassium intake as an alternative evaluation of diet-dependent net acid load. We identified 15 385 incident cases of hypertension during 995 239 person-years of follow-up. After adjusting for potential confounders, women in the top decile of estimated diet-dependent net acid load had an increased risk of hypertension (relative risk: 1.14; 95% CI: 1.05 to 1.24; P for trend=0.01) compared with women in the bottom decile. To test whether the association between estimated diet-dependent net acid load and hypertension is independent of its individual components, an additional adjustment for intakes of protein and potassium was made and resulted in a relative risk of 1.23 (95% CI: 1.08 to 1.41; P for trend=0.003) for the top decile of estimated diet-dependent net acid load. Results of the ratio of animal protein intake to potassium intake were similar with those of estimated diet-depend net acid load. In conclusion, a high diet-dependent net acid load is independently associated with a higher risk of incident hypertension.

Diet and lifestyle risk factors associated with incident hypertension in women

CONTEXT

Hypertension is an important preventable risk factor for death among women. While several modifiable risk factors have been identified, their combined risk and distribution in the population have not been assessed.

OBJECTIVE

To estimate the hypothetical fraction of hypertension incidence associated with dietary and lifestyle factors in women.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 83,882 adult women aged 27 to 44 years in the second Nurses' Health Study who did not have hypertension, cardiovascular disease, diabetes, or cancer in 1991, and who had normal reported blood pressure (defined as systolic blood pressure of < or = 120 mm Hg and diastolic blood pressure of < or = 80 mm Hg), with follow-up for incident hypertension for 14 years through 2005. Six modifiable lifestyle and dietary factors for hypertension were identified. The 6 low-risk factors for hypertension were a body mass index (BMI) of less than 25, a daily mean of 30 minutes of vigorous exercise, a high score on the Dietary Approaches to Stop Hypertension (DASH) diet based on responses to a food frequency questionnaire, modest alcohol intake up to 10 g/d, use of nonnarcotic analgesics less than once per week, and intake of 400 microg/d or more of supplemental folic acid. The association between combinations of 3 (normal BMI, daily vigorous exercise, and DASH-style diet), 4 (3 low-risk factors plus modest alcohol intake), 5 (4 low-risk factors plus avoidance of nonnarcotic analgesics), and 6 (folic acid supplementation > or = 400 microg/d) low-risk factors and the risk of developing hypertension was analyzed.

MAIN OUTCOME MEASURES

Adjusted hazard ratios for incident self-reported hypertension and population attributable risks (PARs).

RESULTS

A total of 12,319 incident cases of hypertension were reported. All 6 modifiable risk factors were independently associated with the risk of developing hypertension during follow-up after also adjusting for age, race, family history of hypertension, smoking status, and use of oral contraceptives. For women who had all 6 low-risk factors (0.3% of the population), the hazard ratio for incident hypertension was 0.22 (95% confidence interval [CI], 0.10-0.51); the hypothetical PAR was 78% (95% CI, 49%-90%) for women who lacked these low-risk factors. The corresponding hypothetical absolute incidence rate difference (ARD) was 8.37 cases per 1000 person-years. The PARs were 72% (95% CI, 57%-82%; ARD, 7.76 cases per 1000 person-years) for 5 low-risk factors (0.8% of the population), 58% (95% CI, 46%-67%; ARD, 6.28 cases per 1000 person-years) for 4 low-risk factors (1.6% of the population), and 53% (95% CI, 45%-60%; ARD, 6.02 cases per 1000 person-years) for 3 low-risk factors (3.1% of the population). Body mass index alone was the most powerful predictor of hypertension, with a BMI of 25 or greater having an adjusted PAR of 40% (95% CI, 38%-41%) compared with a BMI of less than 25.

CONCLUSIONS

Adherence to low-risk dietary and lifestyle factors was associated with a significantly lower incidence of self-reported hypertension. Adopting low-risk dietary and lifestyle factors has the potential to prevent a large proportion of new-onset hypertension occurring among young women.

Menopause, postmenopausal hormone use and risk of incident gout

OBJECTIVE

To prospectively study the relation between menopause, postmenopausal hormone use and risk of gout, since female sex hormones have been postulated to decrease gout risk among women.

METHODS

In the Nurses' Health Study, the association between menopause, age at menopause, postmenopausal hormone use and risk of self-reported physician-diagnosed incident gout among 92 535 women without gout at baseline was examined. Multivariate proportional hazards regression analysis was used to adjust for other risk factors for gout such as age, body mass index, diuretic use, hypertension, alcohol intake and dietary factors.

RESULTS

During 16 years of follow-up (1 240 231 person-years), 1703 incident gout cases were recorded. The incidence rate of gout increased from 0.6 per 1000 person-years in women <45 years of age to 2.5 in women > or =75 years of age (p for trend <0.001). Compared with premenopausal women, postmenopausal women had a higher risk of incident gout (multivariate-adjusted relative risk (RR)=1.26; 95% confidence interval (CI) 1.03 to 1.55). Among women with a natural menopause, women with age at menopause <45 years had a RR of 1.62 (95% CI 1.12 to 2.33) of gout compared with women with age at menopause 50-54 years. Postmenopausal hormone users had a reduced risk of gout (RR=0.82; 95% CI 0.70 to 0.96).

CONCLUSION

These prospective findings indicate that menopause increases the risk of gout, whereas postmenopausal hormone therapy modestly reduces gout risk.

Post-menopausal hormone use and albuminuria

BACKGROUND

Higher levels of urinary albumin excretion predict future hypertension and chronic kidney disease. Post-menopausal hormone use may influence the renin-angiotensin system and renal endothelial function, impacting albumin excretion. The association between post-menopausal hormone use and albuminuria is not well defined.

METHODS

We explored the cross-sectional association between duration of PMH use and albuminuria in 2445 post-menopausal, non-diabetic women from the Nurses' Health Study. Women were categorized as hormone non-users, past users or current users grouped by 3-year intervals of duration of use, from < or =3 years to >15 years. The outcome was the top decile of urine albumin/creatinine ratio (ACR). Multivariate logistic regression was used to assess the association between duration of PMH use and risk of being in the top decile.

RESULTS

The mean age was 66.8 years, and 57% were currently using PMH. The median ACR was 2.9 mg/g, and the 90th percentile was 9.2 mg/g. Compared with women with no history of PMH use, the odds ratio for being in the top ACR decile was lower for women with use of >6-9 years, >9-12 years, >12-15 years and >15 years, but there was no dose-response. The overall odds ratio was 0.55 (95% CI: 0.39-0.77) among women with >6 years of current PMH use compared with non-users. Current hormone use of shorter duration and past hormone use were not associated with albumin excretion.

CONCLUSIONS

Current PMH use of >6 years is associated with a lower urinary ACR in non-diabetic women.

Psoriasis and the risk of diabetes and hypertension: a prospective study of US female nurses

OBJECTIVE

To evaluate the independent association between psoriasis and risk of diabetes and hypertension.

DESIGN

A prospective study of female nurses who were followed up from 1991 to 2005.

SETTING

Nurses' Health Study II, a cohort of 116 671 US women aged 27 to 44 years in 1991.

PARTICIPANTS

The study included 78 061 women who responded to a question about a lifetime history of physician-diagnosed psoriasis in 2005. Women who reported a diagnosis of diabetes or hypertension at baseline were excluded. Main Outcome Measure New diagnosis of diabetes or hypertension, obtained from biennial questionnaires.

RESULTS

Of the 78 061 women, 1813 (2.3%) reported a diagnosis of psoriasis. During the 14 years of follow-up, a total of 1560 incident cases (2%) of diabetes and 15 724 incident cases (20%) of hypertension were documented. The multivariate-adjusted relative risk of diabetes in women with psoriasis compared with women without psoriasis was 1.63 (95% confidence interval, 1.25-2.12). Women with psoriasis were also at an increased risk for the development of hypertension (multivariate relative risk, 1.17; 95% confidence interval, 1.06-1.30). Age, body mass index, and smoking status did not significantly modify the association between psoriasis and risk of diabetes or hypertension (P values for interaction, > or =.07).

CONCLUSIONS

In this prospective analysis, psoriasis was independently associated with an increased risk of diabetes and hypertension. Future studies are needed to find out whether psoriasis treatment will reduce the risk of diabetes and hypertension.

Oral contraceptive use and incident urinary incontinence in premenopausal women

PURPOSE

Recent data in postmenopausal women indicate that current and past use of exogenous hormones is related to urinary incontinence risk. Little is known about exogenous hormones and risk of urinary incontinence in younger women. We investigated the association between oral contraceptive pills and incident urinary incontinence in premenopausal women enrolled in the Nurses' Health Study II.

MATERIALS AND METHODS

Participants reported use of oral contraceptive pills from 1989 to 2001. Among 21,864 premenopausal women 37 to 54 years old reporting no urinary incontinence in 2001 we identified 749 with incident urinary incontinence at least weekly between 2001 and 2003. Odds ratios and 95% confidence intervals were estimated using multivariable logistic regression.

RESULTS

Women who had ever used oral contraceptive pills had a statistically significant 27% (95% CI 1-59) increased odds of experiencing urinary incontinence at least weekly compared with those who never used oral contraceptive pills. In women with 10 or more years of use the odds ratio increased to 1.48 (95% CI 1.13-1.95). Ever using oral contraceptive pills was specifically associated with urgency urinary incontinence (OR 2.48, 95% CI 1.07-5.76) rather than stress urinary incontinence (OR 1.04, 95% CI 0.78-1.40). Although we had limited information on urinary tract infection, control for urinary tract infection did not alter these findings.

CONCLUSIONS

Use of oral contraceptive pills may be associated with a modest increase in the odds of urinary incontinence among premenopausal women. However, this is one of the first reports of such an association and, thus, further research is needed to confirm our findings and investigate possible mechanisms.

Genetic polymorphisms and the risk of accelerated renal function decline in women

Background

Reduced glomerular filtration rate is an important predictor of cardiovascular disease and death. Genetic polymorphisms, particularly in genes involved in the renin-angiotensin system (RAS), may influence the rate of renal function decline.

Methodology/Principal Findings

We examined the relation between specific single nucleotide polymorphisms (SNPs), including those in the RAS, apolipoprotein E and alpha-adducin, and renal function decline assessed by estimated glomerular filtration rate (eGFR) over an 11-year period in 2578 Caucasian participants of the Nurses' Health Study. Logistic regression was used to examine the associations between genotype and risk of eGFR decline of ≥25%.

Results

After 11 years between creatinine measurements, the eGFR declined by ≥25% in 423 of 2578 (16%) women. The angiotensinogen (AGT) A-20C polymorphism was associated with a higher risk of renal function decline when two risk alleles were present than if one or no alleles were present (CC vs AA and AC) OR 1.83 (95% CI 1.02–3.26; p = 0.04). The angiotensin II type 1 receptor (AT₁R) A1166C polymorphism was marginally associated with a higher risk of renal function decline when two risk alleles were present (CC vs AA, OR = 1.41; 95% CI 0.98–2.01; p = 0.06). The alpha-adducin G460W polymorphism was associated with a lower risk of renal function decline when any number of risk alleles were present (WG vs GG, OR = 0.78, 95% CI 0.61–0.99, p = 0.04; WW vs GG, OR = 0.46; 95% CI 0.20–1.07, p = 0.07). Linear regression analysis with change in eGFR as the outcome showed a larger decline of 3.5 (95% CI 0.5 to 6.4, p = 0.02) ml/min/1.73 m² in AGT A-20C CC homozygotes. No other polymorphisms were significantly associated with renal function decline or absolute change in eGFR over the study period.

Conclusions

Genetic variants in the angiotensinogen, angiotensin II type 1 receptor and alpha-adducin genes may contribute to loss of renal function in the general female Caucasian population.

Uric acid and insulin sensitivity and risk of incident hypertension

BACKGROUND

Uric acid, insulin sensitivity, and endothelial dysfunction may be important in the development of hypertension. Corresponding circulating biomarkers are associated with risk of hypertension, but because these factors may be interrelated, whether they independently affect risk is unknown.

METHODS

In 1496 women aged 32 to 52 years without hypertension at baseline, we prospectively analyzed the associations between fasting plasma levels of uric acid, insulin, triglycerides, the insulin sensitivity index, and 2 biomarkers associated with endothelial dysfunction (homocysteine and soluble intercellular adhesion molecule-1) and the odds of incident hypertension. Odds ratios were adjusted for standard risk factors and then for all biomarkers plus estimated glomerular filtration rate and total cholesterol level. Population-attributable risk was estimated for biomarkers significantly associated with hypertension.

RESULTS

All the biomarkers were associated with incident hypertension after adjustment for standard hypertension risk factors. However, after simultaneously controlling for all the biomarkers, estimated glomerular filtration rate, and total cholesterol level, only uric acid and insulin levels were independently associated with incident hypertension. Comparing the highest and lowest quartiles of uric acid levels, the odds ratio was 1.89 (95% confidence interval, 1.26-2.82). A similar comparison yielded an odds ratio of 2.03 (95% confidence interval, 1.35-3.05) for insulin levels. Using an estimated basal incidence rate of 14.6 per 1000 annually, 30.8% of all hypertension occurring in young women annually is associated with uric acid levels of 3.4 mg/dL or greater (to convert to micromoles per liter, multiply by 59.485). For insulin levels of 2.9 microIU/mL or greater (to convert to picomoles per liter, multiply by 6.945), this proportion is 24.2%.

CONCLUSIONS

Differences in uric acid and insulin levels robustly and substantially affect the risk of hypertension in young women. Measuring these biomarkers in clinical practice may identify higher-risk individuals.

Fructose and vitamin C intake do not influence risk for developing hypertension

Higher uric acid levels are associated with an increased risk for developing hypertension. Higher intake of fructose increases plasma uric acid levels and higher intake of vitamin C reduces uric acid levels, but whether these nutrients are independently associated with the risk for developing hypertension is unknown. We studied this question by analyzing data from participants of three large and independent prospective cohorts: Nurses' Health Study 1 (n = 88,540), Nurses' Health Study 2 (n = 97,315), and the Health Professionals Follow-up Study (n = 37,375). Relative risks and 95% confidence intervals for incident hypertension were computed according to quintiles of fructose intake and categories of vitamin C intake using multivariable Cox proportional hazards regression. Fructose intake was not associated with the risk for developing hypertension; the multivariable relative risks (95% confidence intervals) for the highest compared with the lowest quintile of fructose intake were 1.02 (0.99 to 1.06) in Nurses' Health Study 1, 1.03 (0.98 to 1.08) in Nurses' Health Study 2, and 0.99 (0.93 to 1.05) in Heath Professionals Follow-up Study. Regarding vitamin C, the relative risks for individuals who consumed > or =1500 mg/d compared with those who consumed <250 mg/d were 0.89 (0.83 to 0.96) in Nurses' Health Study 1, 1.02 (0.91 to 1.14) in Nurses' Health Study 2, and 1.06 (0.97 to 1.15) in Health Professionals Follow-up Study. In conclusion, fructose and vitamin C intake do not substantially influence the risk for developing hypertension.

Postmenopausal hormone therapy and incident urinary incontinence in middle-aged women

OBJECTIVE

The objective of the study was to examine the association of hormone therapy with incident urinary incontinence (UI) in postmenopausal women aged 37-54 years in the Nurses' Health Study II.

STUDY DESIGN

Participants reported use of hormone therapy, including hormone type, on biennial questionnaires from 1989 to 2001. Among 7341 postmenopausal women reporting no UI in 2001, we identified 1026 women who developed UI at least monthly between 2001 and 2003. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Women currently using hormone therapy had 1.39-fold (95% CI, 1.16-1.67) increased odds of incident UI, compared with women who never used hormone therapy. ORs were similar in current users of oral estrogen alone (OR, 1.35, 95% CI, 1.03-1.78) and oral estrogen with progestin (OR, 1.37, 95% CI, 1.13-1.67).

CONCLUSION

These findings suggest an increased risk of UI associated with use of postmenopausal hormone therapy in younger postmenopausal women.

Current issues in measurement and reporting of urinary albumin excretion

BACKGROUND

Urinary excretion of albumin indicates kidney damage and is recognized as a risk factor for progression of kidney disease and cardiovascular disease. The role of urinary albumin measurements has focused attention on the clinical need for accurate and clearly reported results. The National Kidney Disease Education Program and the IFCC convened a conference to assess the current state of preanalytical, analytical, and postanalytical issues affecting urine albumin measurements and to identify areas needing improvement.

CONTENT

The chemistry of albumin in urine is incompletely understood. Current guidelines recommend the use of the albumin/creatinine ratio (ACR) as a surrogate for the error-prone collection of timed urine samples. Although ACR results are affected by patient preparation and time of day of sample collection, neither is standardized. Considerable intermethod differences have been reported for both albumin and creatinine measurement, but trueness is unknown because there are no reference measurement procedures for albumin and no reference materials for either analyte in urine. The recommended reference intervals for the ACR do not take into account the large intergroup differences in creatinine excretion (e.g., related to differences in age, sex, and ethnicity) nor the continuous increase in risk related to albumin excretion.

DISCUSSION

Clinical needs have been identified for standardization of (a) urine collection methods, (b) urine albumin and creatinine measurements based on a complete reference system, (c) reporting of test results, and (d) reference intervals for the ACR.