Ken Bassett

Gender and blindness: a meta-analysis of population-based prevalence surveys.

BACKGROUND: Many individual surveys of blindness have reported slightly higher rates of blindness for women. In order to gain a continent-by-continent and global sense of the burden of blindness by sex we conducted a meta-analysis of published, population-based surveys of blindness. METHOD: Published reports were collected using a predetermined search protocol involving commercial electronic databases, hand-searching of references and direct contact with researchers. Studies were included that were population-based, included clinical examination and had a minimum sample size of 1000. The studies were critically appraised to determine methodological rigour. Data were analysed using the Cochrane Collaboration Review Manager. RESULTS: The overall odds ratio (age-adjusted) of blind women to men is 1.43 (95% CI 1.33–1.53), ranging from 1.39 (95% CI 1.20–1.61) in Africa, 1.41 (95% CI 1.29–1.54) in Asia, and 1.63 (95% CI 1.30–2.05) in industrialised countries. There was good homogeneity of findings from Africa, Asia, and the industrialised countries. Globally, women bear excess blindness compared to men. In these surveys, overall, women account for 64.5% of all blind people. The excess of blindness in women was marked among the elderly and not due only to differential life expectancy. CONCLUSION: The excess burden of blindness among women is likely due to a number of factors, which are different in industrialised countries compared to developing countries. Particular attention to gender differences in blindness is needed in the creation of targets for blindness reduction and in the development of interventions.

Thiazolidinediones and Fractures in Men and Women

BACKGROUND Clinical trials and meta-analyses have found that rosiglitazone maleate, a thiazolidinedione that is prescribed for type 2 diabetes mellitus, increases the risk of fractures in women. The association between the use of thiazolidinediones and fractures in men and women is not adequately understood. METHODS We conducted a prospective cohort study. The primary outcome was peripheral fractures in men and women who were exposed to thiazolidinediones compared with sulfonylureas. We studied 84 339 patients from British Columbia, Canada, who began treatment with a thiazolidinedione or a sulfonylurea. The association between the use of thiazolidinediones and fractures was examined using multivariate-adjusted Cox models. RESULTS The mean age of the patients in the study was 59 years, and 43% were women. In this cohort, treatment with a thiazolidinedione was associated with a 28% increased risk of peripheral fractures compared with treatment with a sulfonylurea (hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.10-1.48). The use of pioglitazone hydrochloride was associated with an increased risk of peripheral fracture of 77% in women (HR, 1.76; 95% CI 1.32-2.38). Compared with exposure to sulfonylureas, exposure to pioglitazone was associated with more peripheral fractures in men (HR, 1.61; 95% CI 1.18-2.20), but we did not observe a similar association with exposure to rosiglitazone (HR, 1.00; 95% CI, 0.75-1.34). CONCLUSIONS Both men and women who take thiazolidinediones could be at increased risk of fractures. Pioglitazone may be more strongly associated with fractures than rosiglitazone. Larger observational studies are needed, and fracture data from clinical trials need to be fully published so that fracture risks can be known with greater certainty.

A systematic review of craniosacral therapy: Biological plausibility, assessment reliability and clinical effectiveness

OBJECTIVES The objective of this research was to review critically the scientific basis of craniosacral therapy as a therapeutic intervention. DESIGN A systematic search for and critical appraisal of research on craniosacral therapy was conducted. Medline, Embase, Healthstar, Mantis, Allied and Alternative Medicine, Scisearch and Biosis were searched from their start date to February 1999. MAIN OUTCOME MEASURES A three-dimensional evaluative framework with related appraisal criteria: (A) craniosacral interventions and health outcomes; (B) validity of craniosacral assessment; and (C) pathophysiology of the craniosacral system. RESULTS The available research on craniosacral treatment effectiveness constitutes low-grade evidence conducted using inadequate research protocols. One study reported negative side effects in outpatients with traumatic brain injury. Low inter-rater reliability ratings were found. CONCLUSIONS This systematic review and critical appraisal found insufficient evidence to support craniosacral therapy. Research methods that could conclusively evaluate effectiveness have not been applied to date.

Cataract surgical coverage remains lower in women

Background: Cataract remains the leading cause of global blindness. Evidence from population-based surveys, carried out up to 2000, and the launch of the VISION 2020 initiative to address avoidable blindness showed that women in low- and middle-income countries had a lower cataract surgical coverage (CSC) than men. Methods: A systematic review identified population-based surveys reporting CSC in low- and middle-income countries published since 2000. Researchers extracted data on sex-specific CSC rates and estimated the overall CSC differences using meta-analyses. Results: Among the 23 surveys selected for this review, 21 showed higher CSC among men. The Peto odds ratio revealed that men were 1.71 times (95% CI 1.48 to 1.97) more likely to have cataract surgery than women. The risk difference in the rates of surgery varied from −0.025 to 0.276, and the combined average was 0.116 (95% CI 0.082 to 0.149). Discussion: Gender inequity in use of cataract surgical services persists in the low- and middle-income countries. It is estimated in this study that blindness and severe visual impairment from cataract could be reduced by around 11% in the low- and middle-income countries if women were to receive cataract surgery at the same rate as men. Additional effort globally is needed to ensure that women receive the benefits of cataract surgery at the same rate as men.

Blindness prevalence and cataract surgical coverage in Lumbini Zone and Chetwan District of Nepal.

Aim To determine the prevalence of blindness, visual impairment and the cataract surgical coverage for people aged 50 years and older in the Lumbini Zone and the Chitwan District (Narayani Zone) of Nepal. Methods A population-based cross-sectional study in 2006 selected subjects aged 50 years and older through a random multistage cluster sampling and door-to-door enumeration. Ophthalmic examination included visual-acuity assessment and refraction, and anterior and posterior segment examination of the eyes carried out by a trained ophthalmologist and two ophthalmic assistants at centralised locations. Results The survey examined 5138 of 5196 persons enumerated (response rate of 86.8%). The mean age of the subjects was 61 (SD 9.2) years, and 2701 (52.6%) subjects were women. The age–sex-adjusted prevalence of blindness (best presenting vision <6/60) and visual impairment (better-eye presenting visual acuity of <6/18 to ≥6/60) were 4.6% (95% CI 3.4 to 5.8) and 18.9% (95% CI 16.4 to 21.4), respectively. Blindness was significantly lower in the hill (3.3%) compared with the plain (5.8%) regions (OR 0.6; 95% CI 0.4 to 0.9). The primary causes for blind eyes were cataract (n = 228, 48.1%), refractive error (n = 149, 31.4%), retinal disorders (n = 19, 4.0%) and corneal opacity (n = 18, 3.8%). The overall cataract surgical coverage was 66.6%. Cataract surgical coverage was not significantly associated with age, sex, literacy or District. Conclusion Although the prevalence of blindness and visual impairment is lower than 10 years ago, particularly among women, correctable blindness due to cataract and refractive error (79.5% of blind people) remains a significant population health problem in Lumbini Zone and Chitwan District.

Rosiglitazone and Myocardial Infarction in Patients Previously Prescribed Metformin

Objective Rosiglitazone was found associated with approximately a 43% increase in risk of acute myocardial infarction (AMI) in a two meta-analyses of clinical trials. Our objective is to estimate the magnitude of the association in real-world patients previously treated with metformin. Research Design and Methods We conducted a nested case control study in British Columbia using health care databases on 4.3 million people. Our cohort consisted of 158,578 patients with Type 2 diabetes who used metformin as first-line drug treatment. We matched 2,244 cases of myocardial infarction (AMI) with up to 4 controls. Conditional logistic regression models were used to estimate matched odds ratios for AMI associated with treatment with rosiglitazone, pioglitazone and sulfonylureas. Results In our cohort of prior metformin users, adding rosiglitazone for up to 6 months was not associated with an increased risk of AMI compared to adding a sulfonylurea (odds ratio [OR] 1.38; 95% confidence interval [CI], 0.91–2.10), or compared to adding pioglitazone (OR for rosi versus pio 1.41; 95% CI, 0.74–2.66). There were also no significant differences between rosiglitazone, pioglitazone and sulfonylureas for longer durations of treatment. Though not significantly different from sulfonylureas, there was a transient increase in AMI risk associated with the first 6 months of treatment with a glitazone compared to not using the treatment (OR 1.53; 95% CI, 1.13–2.07) Conclusions In our British Columbia cohort of patients who received metformin as first-line pharmacotherapy for Type 2 diabetes mellitus, further treatment with rosiglitazone did not increase the risk of AMI compared to patients who were treated with pioglitazone or a sulfonylurea. Though not statistically significantly different compared from each other, an increased risk of AMI observed after starting rosiglitazone or sulfonylureas is a matter of concern that requires more research.

Changes in rates of upper gastrointestinal hemorrhage after the introduction of cyclooxygenase-2 inhibitors in British Columbia and Ontario

Background: Population rates of upper gastrointestinal (GI) hemorrhage have been observed to increase with the introduction and rapid uptake of selective cyclooxygenase-2 (COX-2) inhibitors. Changes in COX-2 inhibitor use and upper GI bleeding rates in regions with relatively restrictive drug policies (e.g., British Columbia) have not been compared with changes in regions with relatively less restrictive drug policies (e.g., Ontario). Methods: We collected administrative data for about 1.4 million people aged 66 years and older in British Columbia and Ontario for the period January 1996 to November 2002. We examined temporal changes in the prevalence of NSAID use and admissions to hospital because of upper GI hemorrhage in both provinces using cross-sectional time series analysis. Results: During the period studied, the prevalence of NSAID use in British Columbias population of older people increased by 25% (from 8.7% to 10.9%; p < 0.01), as compared with a 51% increase in Ontario (from 10.9% to 16.5%; p < 0.01). Hospital admissions because of upper GI hemorrhage increased significantly in Ontario by about 16% on average, or about 2 admissions per 10 000 elderly people, above expected values (p < 0.01). A similar increase was not observed in British Columbia. Interpretation: More restrictive drug coverage policies, although limiting access to drugs and their potential benefits, may protect the population from adverse drug effects.

Cataract Surgical Outcome and Predictors of Outcome in Lumbini Zone and Chitwan District of Nepal

Purpose: To evaluate visual acuity outcome from cataract surgery based on a population-based survey among people aged 50 years and older in Lumbini Zone and Chitwan District of Nepal. Methods: A randomly selected, population-based cross sectional epidemiological study of blindness, visual impairment and cataract surgical outcome was conducted. All subjects underwent a comprehensive ocular examination by an ophthalmic assistant, while people with visual impairment (visual acuity less than 6/18) after refraction and all cataract surgical cases underwent dilated fundus examination by an ophthalmologist. Results: 5,916 people were enumerated and 5,141 (86.9%) examined. Among the 359 people who had cataract surgery, 485 eyes were included in the study. First eye surgery was before 2000 in 84 (23%), between 2000 and 2003 in 130 (36%), and after 2003 in 145 (41%). A presenting visual acuity ≥ 6/18 was achieved in 298 (61.4%) eyes (10 [17.8%] and 288 [67.1%] of aphakic and pseudophakic eyes, respectively) and best corrected vision ≥ 6/18 in 411 (84.7%) in all eyes. A presenting visual acuity less than 6/60 was found in 27 (6.3%) pseudophakic eyes. There was no significant difference in visual outcome based on age, sex, literacy, or institution. Uncorrected refractive error was the main cause (72.9%) of visual impairment in pseudophakic eyes. Conclusions: Visual acuity outcome after cataract surgery requires further improvement to meet World Health Organization standards, particularly improvement in preoperative biometry and refractive services. The same quality cataract surgery was provided in and equitably distributed throughout Lumbini Zone and Chitwan District independent of age, sex, literacy or location.

Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic

Aim: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation. Methods: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters. Results: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence. Conclusions: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

Comparative persistence of the TNF antagonists in rheumatoid arthritis--a population-based cohort study.

Objective To compare persistence with tumor necrosis factor alpha (TNF) antagonists among rheumatoid arthritis patients in British Columbia. Treatment persistence has been suggested as a proxy for real-world therapeutic benefit and harm of treatments for chronic non-curable diseases, including rheumatoid arthritis. We hypothesized that the different pharmacological characteristics of infliximab, adalimumab and etanercept cause statistically and clinically significant differences in persistence. Methods We conducted a population-based cohort study using administrative health data from the Canadian province of British Columbia. The study cohort included rheumatoid arthritis patients who initiated the first course of a TNF antagonist between 2001 and 2008. Persistence was measured as the time between first dispensing to discontinuation. Drug discontinuation was defined as a drug-free interval of 180 days or switching to another TNF antagonist, anakinra, rituximab or abatacept. Persistence was estimated and compared using survival analysis. Results The study cohort included 2,923 patients, 63% treated with etanercept. Median persistence in years (95% confidence interval) with infliximab was 3.7 (2.9–4.9), with adalimumab 3.3 (2.6–4.1) and with etanercept 3.8 (3.3–4.3). Similar risk of discontinuation was observed for the three drugs: the hazard ratio (95% confidence interval) was 0.98 (0.85–1.13) comparing infliximab with etanercept, 0.95 (0.78–1.15) comparing infliximab with adalimumab and 1.04 (0.88–1.22) comparing adalimumab with etanercept. Conclusions Similar persistence was observed with infliximab, adalimumab and etanercept in rheumatoid arthritis patients during the first 9 years of use. If treatment persistence is a good proxy for the therapeutic benefit and harm of these drugs, then this finding suggests that the three drugs share an overall similar benefit-harm profile in rheumatoid arthritis patients.