Objectives To systematically review and quantitatively synthesize the effect of vitamin D therapy on fall prevention in older adults. Design Systematic review and meta-analysis. Setting MEDLINE, CINAHL,Web of Science, EMBASE, Cochrane Library, LILACS, bibliographies of selected articles, and previous systematic reviews through February 2009 were searched for eligible studies. Participants Older adults (aged ≥60 years) who participated in randomized controlled trials that investigated the effectiveness of vitamin D therapy in the prevention of falls and used an explicit fall definition. Measurements Two authors independently extracted data including study characteristics, quality assessment, and outcomes. The I2 statistic was used to assess heterogeneity in a randomeffects model. Results Of 1,679 potentially relevant articles, 10 studies met inclusion criteria. In pooled analysis, vitamin D therapy (200-1000IU) reduced falls by 14% (relative risk [RR] 0.86;95% confidence interval 0.79-0.93;I2=7%) compared to calcium or placebo; number needed to treat=15. The following subgroups had significant fall reductions: community-dwelling (age<80 years), adjunctive calcium supplementation, no history of fractures/falls, duration>6 months, cholecalciferol, and dose≥800 IU. Meta-regression demonstrated no linear association of vitamin D dose or duration with treatment effect. Post-hoc analysis, including 7 additional studies (17 total) without explicit fall definitions, yielded smaller benefit (RR 0.92,0.87-0.98) and more heterogeneity (I2=36%) but found significant intergroup differences favoring adjunctive calcium versus none (p=0.001). Conclusion Vitamin D treatment effectively reduces the risk of falls in older adults. Future studies should investigate whether particular populations or treatment regimens may have greater benefit.

Objective Gout is often defined by self-report in epidemiologic studies. Yet the validity of self-reported gout is uncertain. We evaluated the reliability and sensitivity of the self-report of physician-diagnosed gout in the Campaign Against Cancer and Heart Disease (CLUE II) and the Atherosclerosis Risk in the Community (ARIC) cohorts. Methods The CLUE II cohort comprises 12,912 individuals who self-reported gout status on either the 2000, 2003, or 2007 questionnaires. We calculated reliability as the percentage of participants reporting having gout on more than 1 questionnaire using Cohen’s κ statistic. The ARIC cohort comprises 11,506 individuals who self-reported gout status at visit 4. We considered a hospital discharge diagnosis of gout or use of a gout-specific medication as the standard against which to calculate the sensitivity of self-reported, physician-diagnosed gout. Results Of the 437 CLUE II participants who self-reported physician-diagnosed gout in 2000, and subsequently answered the 2003 questionnaire, 75% reported gout in 2003 (κ = 0.73). Of the 271 participants who reported gout in 2000, 73% again reported gout at the 2007 followup questionnaire (κ = 0.63). In ARIC, 196 participants met the definition for gout prior to visit 4 and self-reported their gout status at visit 4. The sensitivity of a self-report of physician-diagnosed gout was 84%. Accuracy was similar across sex and race subgroups, but differed across hyperuricemia and education strata. Conclusion These 2 population-based US cohorts suggest that self-report of physician-diagnosed gout has good reliability and sensitivity. Thus, self-report of a physician diagnosis of gout is appropriate for epidemiologic studies.

Objective To quantify the role of diuretic use on gout development in an adult population with hypertension. Methods ARIC, a prospective population-based cohort from 4 US communities, consists of 4 visits over a 9-year period. Participants were included in this analysis if they answered the gout query, were free of gout at baseline, and had hypertension (medication to treat hypertension or a blood pressure ≥ 140/90 mmHg). Trained interviewers recorded antihypertensive use. Incident gout was defined as self-reported onset after baseline. Using a time-dependent Cox Proportional Hazards model, we estimated the hazard rate ratio (HR) of incident gout by time-varying diuretic use, adjusted for confounders, and tested for mediation by serum urate level. Results There were 5,789 hypertensive participants; 37% were treated with a diuretic. Use of any diuretic (HR=1.48, 95% CI: 1.11, 1.98), thiazide diuretic (HR=1.44, 95% CI: 1.00, 2.10), and loop diuretic (HR=2.31, 95% CI: 1.36, 3.91) was associated with incident gout compared with not using any diuretic, thiazide diuretic or loop diuretics, respectively. After adjusting for serum urate, the association between diuretic use and gout was null. Use of antihypertensive medication other than diuretic agents was associated with decreased gout risk (adjusted HR=0.64 95% CI: 0.49, 0.86) compared to untreated hypertension. The longitudinal change in serum urate was 0.72 mg/dL (95% CI: 0.57, 0.87) higher in those who initiated a diuretic compared with those who did not (p-value<0.001). Conclusions Thiazide and loop diuretics were associated with increased gout risk, an association mediated by a change in serum urate.

Some observational studies have identified elevated uric acid concentration as a risk factor for diabetes, while others have found an inverse relationship. We examined both the association of uric acid level with incident diabetes and the change in uric acid concentration after a diabetes diagnosis. We analyzed data from the Atherosclerosis Risk in Communities (ARIC) Study and quantified the independent association between uric acid level and incident diabetes via Cox proportional hazards models. The association between duration of diabetes and change in uric acid level was examined via linear regression. Among 11,134 participants without diagnosed diabetes at baseline (1987-1989), there were 1,294 incident cases of diabetes during a median of 9 years of follow-up (1987-1998). Uric acid level was associated with diabetes even after adjustment for risk factors (per 1 mg/dL, hazard ratio = 1.18, 95% confidence interval: 1.13, 1.23), and the association remained significant after adjustment for fasting glucose and insulin levels. Among participants with diabetes (n = 1,510), every additional 5 years' duration of diabetes was associated with a 0.10-mg/dL (95% confidence interval: 0.04, 0.15) lower uric acid level after adjustment. We conclude that uric acid concentration rises prior to diagnosis of diabetes and then declines with diabetes duration. Future studies investigating uric acid as a risk factor for cardiovascular disease should adequately account for the impact and timing of diabetes development.

We quantified the impact of hypertension on gout incidence in middle-aged white and African American, men and women. ARIC is a prospective population-based cohort recruited between 1987–1989 from 4 US communities. Using a time-dependent Cox Proportional Hazards model, we estimated the adjusted hazard ratio (HR) of incident gout by time-varying hypertension and tested for mediation by serum urate level. There were 10,872 participants among whom 45% had hypertension over follow-up; 43% were men and 21% were African-American. Over 9 years, 274 (2.5%) participants developed gout; 1.8% of women and 3.5% of men. The unadjusted HR of incident gout was approximately 3 times (HR=2.87; 95% CI: 2.24, 3.78) greater for those with hypertension. Adjusting for confounders resulted in an attenuated but still significant association between hypertension and gout (HR= 2.00; 95% CI: 1.54, 2.61). Adjustment for serum urate level further attenuated but did not abrogate the association (HR=1.36, 95% CI: 1.04, 1.79). There was no evidence of effect modification by sex (p-value=0.35), race (p-value=0.99), or obesity at baseline (p-value=0.82). Hypertension was independently associated with increased gout risk in middle-aged African American and white adults. Serum urate level may be a partial intermediate on the pathway between hypertension and gout.