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

Exposure to antipsychotics and risk of stroke: self controlled case series study

Objectives To investigate the association between use of typical and atypical antipsychotic drugs and incidence of stroke in patients with and without dementia