The association between Parkinson's disease and anti-epilepsy drug carbamazepine: a case-control study using the UK General Practice Research Database.

AIMS: To investigate whether the use of carbamazepine is associated with reduced risk of Parkinson's disease. METHODS: We conducted a population-based, matched case-control study of patients randomly selected from the UK General Research Practice Database. We identified 8549 patients with Parkinson's disease using diagnosis criteria with a positive predictive value of 90%. These patients were compared with 42, 160 control subjects matched for age, sex and general practice. RESULTS: Overall, 3.0% of cases (257 of 8549) had at least one recorded prescription for carbamazepine compared with 2.5% (1050 of 42, 160) of controls. The crude odds ratio for the association between Parkinson's disease and carbamazepine was 1.22 (95% confidence interval 1.06-1.40), but this reduced to 0.93 (95% confidence interval 0.81-1.08, P = 0.34) after adjusting for annual consultation rate. Further adjustment for body mass index, smoking status, alcohol consumption or use of calcium channel blockers did not affect results. There was no evidence that risk decreased with higher doses or longer duration of carbamazepine use. CONCLUSIONS: There was little to no evidence that use of carbamazepine is associated with reduced risk of Parkinson's disease. Although the study was underpowered, it does indicate that any effect of carbamazepine is likely to be small

Hospital admissions in older people with visual impairment in Britain.

BACKGROUND: We aimed to assess the risk of hospital admission associated with visual impairment in a representative sample of older people living in the community in Britain. METHODS: DESIGN: Prospective study of hospital admission in a population-based sample of community dwelling people aged 75 years and above in Britain. SETTING: 53 general practices. PARTICIPANTS: 14,394 participants in the MRC Trial of Assessment and Management of Older people in the Community. MAIN OUTCOME MEASURE: Hospital admission. RESULTS: Visually impaired older people had 238.7 admissions/1000 person-years compared to 169.7 admissions/1000 person-years in people with good vision: age and sex adjusted rate ratio (RR) 1.32 (95% CI 1.19 to 1.47). Adjusting for a wide range of potential explanatory factors largely eliminated this association: RR 1.06 (95% CI 0.94 to 1.20). However, adjusting for a more limited range of confounding factors, excluding those factors possibly a consequence of reduced vision, left a modest increased risk: RR 1.19 (95% CI 1.06 to 1.34). CONCLUSION: The association between visual impairment and rate of hospital admission can be attributed to higher levels of co-morbidity and reduced functional ability among people with reduced vision. Visual impairment is likely to be an important contributor to reduced functional ability, but other factors may also be involved

What is the difference between missing completely at random and missing at random?

The terminology describing missingness mechanisms is confusing. In particular the meaning of 'missing at random' is often misunderstood, leading researchers faced with missing data problems away from multiple imputation, a method with considerable advantages. The purpose of this article is to clarify how 'missing at random' differs from 'missing completely at random' via an imagined dialogue between a clinical researcher and statistician

A case-control study of drug risk factors for age-related macular degeneration.

OBJECTIVE: To investigate the association between age-related macular degeneration (AMD) and exposure to antacids, antithyroids, thyroid hormones, and thiazide diuretics. DESIGN: Matched case-control study. PARTICIPANTS: Population-based participants were selected from the United Kingdom General Practice Research Database. A total of 18,007 people with diagnosed AMD were compared with 86 169 controls matched for age, gender, and general practice. METHODS: Conditional logistic regression was used to determine the association between exposure to each drug group of interest and a diagnosis of AMD, adjusting for relevant confounding variables. MAIN OUTCOME MEASURES: The primary outcome was the odds ratio for the association between exposure to antacids, antithyroids, thyroid hormones, or thiazide diuretics and AMD. Secondary analyses were conducted to assess the effect of recent exposure to the drugs of interest, the total number of prescriptions received, and restricting the data set to participants with more than 2 years of observation time. RESULTS: The crude odds ratios for association between any record of drug exposure and AMD were as follows: 1.34 (95% confidence interval [CI], 1.29-1.39) for antacids; 1.15 (95% CI, 0.92-1.44) for antithyroids; 1.34 (95% CI, 1.29-1.39) for thyroid hormones; and 1.13 (95% CI, 1.08-1.17) for thiazide diuretics. After adjusting for consultation rate, observation time, diabetes, heart failure, hyperlipidemia, cardiovascular drug use, atherosclerosis, hypertension, aspirin use, hormone replacement therapy use, body mass index, alcohol consumption, and smoking, the odds ratios reduced to: 1.06 (95% CI, 1.02-1.10) for antacids, 0.98 (95% CI, 0.78-1.24) for antithyroids, 0.99 (95% CI, 0.92-1.06) for thyroid hormones, and 0.98 (95% CI, 0.94-1.02) for thiazides. Secondary analyses were consistent with these findings for all 4 drug categories. CONCLUSIONS: No association was detected between short- and medium-term use of antithyroids, thyroid hormones, and thiazide diuretics and the risk of AMD. Short- and medium-term use of antacids seems to be associated with a small increase in the risk of this disease. However, this increased risk is likely the result of residual confounding by smoking or uncontrolled confounding resulting from socioeconomic status. No conclusions could be drawn regarding longer-term use of each drug category

A Systematic Review of Tobacco Smoking Prevalence and Description of Tobacco Control Strategies in Sub-Saharan African Countries; 2007 to 2014.

OBJECTIVE: To systematically review current smoking prevalence among adults in sub-Saharan Africa from 2007 to May 2014 and to describe the context of tobacco control strategies in these countries. DATA SOURCES: Five databases, Medline, Embase, Africa-wide Information, Cinahl Plus, and Global Health were searched using a systematic search strategy. There were no language restrictions. STUDY SELECTION: 26 included studies measured current smoking prevalence in nationally representative adult populations in sub-Saharan African countries. DATA EXTRACTION: Study details were independently extracted using a standard datasheet. Data on tobacco control policies, taxation and trends in prices were obtained from the Implementation Database of the WHO FCTC website. RESULTS: Studies represented 13 countries. Current smoking prevalence varied widely ranging from 1.8% in Zambia to 25.8% in Sierra Leone. The prevalence of smoking was consistently lower in women compared to men with the widest gender difference observed in Malawi (men 25.9%, women 2.9%). Rwanda had the highest prevalence of women smokers (12.6%) and Ghana had the lowest (0.2%). Rural, urban patterns were inconsistent. Most countries have implemented demand-reduction measures including bans on advertising, and taxation rates but to different extents. CONCLUSION: Smoking prevalence varied widely across sub-Saharan Africa, even between similar country regions, but was always higher in men. High smoking rates were observed among countries in the eastern and southern regions of Africa, mainly among men in Ethiopia, Malawi, Rwanda, and Zambia and women in Rwanda and rural Zambia. Effective action to reduce smoking across sub-Saharan Africa, particularly targeting population groups at increased risk remains a pressing public health priority