Confirmation of self-reported cataract in the Physicians' Health Study

Adiposity by Differing Measures and the Risk of Cataract in the UK Biobank: The Importance of Diabetes

Purpose

To examine the association between adiposity by differing measures and incident cataract and identify important factors contributing to the association.

Methods

Our analysis included 153,139 adults from the UK Biobank, aged 40 to 70 years at baseline (2006-2010). Cataract was ascertained using hospital inpatient, and self-reported data until the early of 2021. Anthropometric measures, body fat percentage, and glycosylated hemoglobin (HbA1c) were measured at baseline.

Results

During a median follow-up of 10.9 years, 15,255 cases of incident cataract were documented. HbA1c was an important contributor to the association between obesity and incident cataract. Obesity; defined by body mass index was associated with an increased risk of cataract (hazard ratio [HR], 1.21 95% confidence interval [CI], 1.16-1.26), and this association was attenuated but remained significant after additional adjustment for HbA1c (HR, 1.05; 95% CI, 1.00-1.10). Similar results were observed for obesity defined by waist circumference or waist-to-hip ratio. Obesity defined by fat percentage was associated with an increased risk of cataract before but not after adjustment for covariates. The association between obesity defined by body mass index and incident cataract was positively significant in individuals with normal HbA1c (HR, 1.07; 95% CI, 1.02-1.13), but inversely significant in those with prediabetes (HR, 0.80; 95% CI, 0.67-0.96) or diabetes (HR, 0.74; 95% CI, 0.61-0.89).

Conclusions

Anthropometric measurements are more predictive of cataract than bioelectrical impedance measures. Diabetes plays an important role in the association between obesity and incident cataract.

Alcohol Consumption and Incident Cataract Surgery in Two Large UK Cohorts

Purpose

To examine the association of alcohol consumption and type of alcoholic beverage with incident cataract surgery in 2 large cohorts.

Design

Longitudinal, observational study.

Participants

We included 469 387 participants of UK Biobank with a mean age of 56 years and 23 162 participants of European Prospective Investigation of Cancer (EPIC)-Norfolk with a mean age of 59 years.

Methods

Self-reported alcohol consumption at baseline was ascertained by a touchscreen questionnaire in UK Biobank and a food-frequency questionnaire in EPIC-Norfolk. Cases were defined as participants undergoing cataract surgery in either eye as ascertained via data linkage to National Health Service procedure statistics. We excluded participants with cataract surgery up to 1 year after the baseline assessment visit or those with self-reported cataract at baseline. Cox proportional hazards models were used to examine the associations of alcohol consumption with incident cataract surgery, adjusted for age, sex, ethnicity, Townsend deprivation index, body mass index (BMI), smoking, and diabetes status.

Main Outcome Measures

Incident cataract surgery.

Results

There were 19 011 (mean cohort follow-up of 95 months) and 4573 (mean cohort follow-up of 193 months) incident cases of cataract surgery in UK Biobank and EPIC-Norfolk, respectively. Compared with nondrinkers, drinkers were less likely to undergo cataract surgery in UK Biobank (hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.85–0.93) and EPIC-Norfolk (HR, 0.90; 95% CI, 0.84–0.97) after adjusting for covariables. Among alcohol consumers, greater alcohol consumption was associated with a reduced risk of undergoing cataract surgery in EPIC-Norfolk (P < 0.001), whereas a U-shaped association was observed in the UK Biobank. Compared with nondrinkers, subgroup analysis by type of alcohol beverage showed the strongest protective association with wine consumption; the risk of incident cataract surgery was 23% and 14% lower among those in the highest category of wine consumption in EPIC-Norfolk and UK Biobank, respectively.

Conclusions

Our findings suggest a lower risk of undergoing cataract surgery with low to moderate alcohol consumption. The association was particularly apparent with wine consumption. We cannot exclude the possibility of residual confounding, and further studies are required to determine whether this association is causal in nature.

The association between self-reported cataracts and St. John's Wort

BACKGROUND/AIMS

Recent interest in Hypericum perforatum, or St. John's Wort (SJW), is related to its observed utility in treating depression. However, mounting evidence suggests one component, hypericin, may be associated with cataractogenesis. To date, this association has not been evaluated in humans. Therefore, the current study assesses the relationship between self-reported SJW use and cataracts utilizing data from a large, population-based sample.

METHODS

Self-reported data on SJW use in the past 12 months and cataract were obtained from the 2002 National Health Interview Survey, a nationally representative population-based sample. Crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) between SJW use and cataracts were estimated using logistic regression.

RESULTS

After adjusting for potential confounding characteristics, participants that reported having cataracts were 59% more likely to report SJW use (OR 1.59; 95% CI 1.02-2.46).

CONCLUSIONS

The results of the current study provide support for an association between SJW use and cataracts. Based on the methodological limitations of this study, further investigation is required.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 2, 2007), MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and The Chinese Biomedical Database from inception to October 2007. We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining occurrence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two authors (GB and DN) independently selected trials for inclusion and extracted data. Outcome measures were gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on random-effects and fixed-effect model meta-analysis. Meta-regression assessed the effect of covariates across the trials.

MAIN RESULTS

We identified 20 randomised trials (211,818 participants), assessing beta-carotene (12 trials), vitamin A (4 trials), vitamin C (8 trials), vitamin E (10 trials), and selenium (9 trials). Trials quality was generally high. Heterogeneity was low to moderate. Antioxidant supplements were without significant effects on gastrointestinal cancers (RR 0.94, 95% CI 0.83 to 1.06). However, there was significant heterogeneity (I(2) = 54.0%, P = 0.003). The heterogeneity may have been explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96 to 1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43 to 0.80; test of interaction P < 0.0005), and type of antioxidant supplement (beta-carotene potentially increasing and selenium potentially decreasing cancer risk). The antioxidant supplements had no significant effects on mortality in a random-effects model meta-analysis (RR 1.02, 95% CI 0.97 to 1.07, I(2) = 53.5%), but significantly increased mortality in a fixed-effect model meta-analysis (RR 1.04, 95% CI 1.02 to 1.07). Beta-carotene in combination with vitamin A (RR 1.16, 95% CI 1.09 to 1.23) and vitamin E (RR 1.06, 95% CI 1.02 to 1.11) significantly increased mortality. Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In five trials (four with high risk of bias), selenium seemed to show significant beneficial effect on gastrointestinal cancer occurrence (RR 0.59, 95% CI 0.46 to 0.75, I(2) = 0%).

AUTHORS' CONCLUSIONS

We could not find convincing evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, antioxidant supplements seem to increase overall mortality. The potential cancer preventive effect of selenium should be tested in adequately conducted randomised trials.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 1, 2003), MEDLINE, EMBASE, LILACS, and SCI-EXPANDED from inception to February 2003, and The Chinese Biomedical Database (March 2003). We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining the incidence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted data. The outcome measures were incidence of gastrointestinal cancers, overall mortality, and adverse events. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on fixed and random effects meta-analyses.

MAIN RESULTS

We identified 14 randomised trials (170,525 participants), assessing beta-carotene (9 trials), vitamin A (4 trials), vitamin C (4 trials), vitamin E (5 trials), and selenium (6 trials). Trial quality was generally high. Heterogeneity was low to moderate. Neither the fixed effect (RR 0.96, 95% CI 0.88 to 1.04) nor random effects meta-analyses (RR 0.90, 95% CI 0.77 to 1.05) showed significant effects of supplementation with antioxidants on the incidences of gastrointestinal cancers. Among the seven high-quality trials reporting on mortality (131,727 participants), the fixed effect (RR 1.06, 95% CI 1.02 to 1.10) unlike the random effects meta-analysis (RR 1.06, 95% CI 0.98 to 1.15) showed that antioxidant supplements significantly increased mortality. Two low-quality trials (32,302 participants) found no significant effect of antioxidant supplementation on mortality. The difference between the mortality estimates in high- and low-quality trials was significant by test of interaction (z = 2.10, P = 0.04). Beta-carotene and vitamin A (RR 1.29, 95% CI 1.14 to 1.45) and beta-carotene and vitamin E (RR 1.10, 95% CI 1.01 to 1.20) significantly increased mortality, while beta-carotene alone only tended to do so (RR 1.05, 95% CI 0.99 to 1.11). Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In four trials (three with unclear/inadequate methodology), selenium showed significant beneficial effect on gastrointestinal cancer incidences.

REVIEWERS' CONCLUSIONS

We could not find evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, they seem to increase overall mortality. The potential cancer preventive effect of selenium should be studied in adequately conducted randomised trials.

Prevalence of cataract in the Speedwell Cardiovascular Study: a cross-sectional survey of men aged 65-83

AIMS

To ascertain the prevalence of cataract in a representative group of men who have been followed since 1979 for cardiovascular disease.

METHODS

Of 2348 men aged 45-63 recruited in 1979 to the Speedwell Cardiovascular Study, 1420 were alive and willing to take part in further studies in 1997. They were sent a questionnaire about their eye health and invited to an ophthalmological examination at Bristol Eye Hospital. Cataract was graded using the Lens Opacities Classification System III (LOCS III) method.

RESULTS

Of the 1420 men, 26 died before they could be examined. Out of the remaining 1394 men, 949 presented for examination and full information was available for 936. Some information about eye health was obtainable for 394 men and 51 were not contactable. The prevalence of cataract increased with age and 36 men (3.8%) had had previous cataract surgery in either or both eyes. Of the remaining 903 men with no previous history of cataract surgery, cortical cataract was present in the right eye of 75 men (8.3%), nuclear (opalescence) in 128 (14.2%) and posterior subcapsular in 15 (1.7%). Five men (0.6%) had visual acuity of 6/60 or worse attributable to cataract in the right eye and 232 (25%) had visual acuity in one or both eyes of 6/24 or less at least partially attributable to cataract. There was no association between social class and the presence of cataract.

CONCLUSIONS

The prevalence of cataract in a representative cohort of men followed since 1979 for cardiovascular disease was comparable to that previously reported in the UK and is consistent with studies from around the world. It appears that substantial amounts of visual loss, attributable to cataract, are present in men. Further studies establishing the reasons for this should be undertaken.

The Roche European American Cataract Trial (REACT): a randomized clinical trial to investigate the efficacy of an oral antioxidant micronutrient mixture to slow progression of age-related cataract

CONTEXT

Funding surgery worldwide for age-related cataract (ARC), a leading cause of blindness, is a huge economic burden. Non-surgical means of slowing ARC progression could benefit patients and reduce this burden.

OBJECTIVE

To determine if a mixture of oral antioxidant micronutrients [mg/day] (beta-carotene [18], vitamin C [750], and vitamin E [600]) would modify progression of ARC.

DESIGN

REACT was a multi-centered, prospective, double-masked, randomized, placebo-controlled, 3-year trial.

SETTING

Consecutive adult American and English outpatients with early ARC were recruited.

PATIENTS

Four-hundred-and-forty-five patients were eligible; 297 were randomized; 231 (78%) were followed for two years; 158 (53%) were followed for three years; 36 (12%) were followed for four years. Twelve patients died during the trial (9 on vitamins; 3 on placebo (p = 0.07)). There were no serious safety issues.

INTERVENTION

After a three-month placebo run-in, patients were randomized by clinical center to the vitamin or placebo groups and followed every four months.

MAIN OUTCOME MEASURE

Cataract severity was documented with serial digital retroillumination imagery of the lens; progression was quantified by image analysis assessing increased area of opacity. This measure of area, 'increase % pixels opaque' (IPO), was the main outcome measure.

RESULTS

There were no statistically significant differences between the treatment groups at baseline. The characteristics of dropouts and the mean follow-up times by treatment group were the same. After two years of treatment, there was a small positive treatment effect in U.S. patients (p = 0.0001); after three years a positive effect was apparent (p = 0.048) in both the U.S. and the U.K. groups. The positive effect in the U.S. group was even greater after three years: (IPO = 0.389 (vitamin) vs. IPO = 2.517 (placebo); p = 0.0001). There was no statistically significant benefit of treatment in the U.K. group. In spite of nearly perfect randomization into treatment groups, the U.S. and U.K. cohorts differed significantly.

CONCLUSION

Daily use of the afore-mentioned micronutrients for three years produced a small deceleration in progression of ARC.

Relations of body fat distribution and height with cataract in men

BACKGROUND

Cataract is the leading cause of blindness worldwide. Body mass index (BMI; in kg/m(2)) is a risk factor for cataract, but other anthropometric measurements may also be important.

OBJECTIVE

We tested relations of alternative measures of body size, including height and waist-to-hip ratio (WHR), as well as BMI, with cataract.

DESIGN

This was a prospective follow-up study. We analyzed data from 20271 participants in the Physicians' Health Study who did not have cataract at baseline and for whom there was complete information on weight, height, and other risk factors. For analyses concerning WHR, we excluded 3121 additional men for whom we did not have these measurements, assessed at the ninth year of follow-up. The main outcome measures were incident cataract and cataract surgery.

RESULTS

Among the 17150 men for whom there were complete data, we confirmed an incident cataract in 1727 during an average of 14 y of follow-up. In proportional hazards regression models that adjusted for many known or suspected risk factors, higher BMI [rate ratio (RR) = 1.25 for >/=27.8 compared with <22, P: for trend = 0. 03], height (RR = 1.23 for >/=184 cm compared with </=170 cm, P: for trend = 0.02), and WHR (RR = 1.31 for top compared with bottom quintile, P: for trend = 0.003) were each independently associated with incident cataract.

CONCLUSIONS

In addition to BMI, both height and abdominal adiposity are independent risk factors for cataract. These relations are biologically plausible and, if causal, suggest that prevention of obesity and beneficial lifestyle changes resulting in weight loss and reduction of central obesity would lessen the incidence and costs of cataract.

Serum ascorbic acid and other correlates of self-reported cataract among older Americans

The purpose of this study was to examine the correlates of self-reported cataract among older Americans, and specifically, to determine whether serum ascorbic acid levels are associated with a decreased prevalence of cataract. A national probability survey of Americans, the Second National Health and Nutrition Examination Survey (NHANES II), was conducted between 1976 and 1980. A total of 4001 participants were included between the ages of 60 and 74 years with data on serum ascorbic acid level and other variables of interest. A total of 252 women (12%) and 164 men (9%) reported a history of cataract. Serum ascorbic acid level was inversely associated with prevalence of cataract in multiple logistic regression analyses; each 1 mg/dl increase was independently associated with a 26% decrease in cataract (P = 0.03). Other independent correlates of cataract included increasing age, female sex, smoking, and diabetes mellitus (all P<0.01). We identified four correlates of cataract among older Americans: serum ascorbic acid level, increasing age, smoking, and diabetes mellitus. Ascorbic acid, a water-soluble antioxidant found in high concentrations in the lens, may be of importance for the prevention of cataract among older Americans.