How effective are dose-adjusted warfarin and aspirin for the prevention of stroke in patients with chronic atrial fibrillation? An analysis of the UK General Practice Research Database

The objective of this study was to evaluate the rate of stroke associated with aspirin and warfarin in routine clinical practice. The study included patients aged 40+ with chronic atrial fibrillation (cAF) registered in the UK General Practice Research Database. The outcome was the rate of stroke during current, past and no use of aspirin and warfarin. The study included 51,807 cAF patients. There was no difference in the rate of stroke between current and past use of aspirin (relative rate [RR] = 1.04 [95% confidence interval (CI) 0.94 - 1.15]), while the rate of stroke was reduced during current warfarin use compared to past use (RR = 0.62 [95% CI 0.54 - 0.71]). For warfarin, a pattern of lower rates of stroke during current exposure and higher rates with past exposure was seen only in patients treated for at least 6-12 months. For aspirin, no changes in the rates of stroke were observed with discontinuation of aspirin. The effectiveness of warfarin was dependent on the level of anticoagulation, with optimal risk reduction occurring within the recommended international normalised ratio (INR) range of 2.0 to 3.0. The proportion of patients achieving a stable INR within the target therapeutic range was at its lowest during the first three months of warfarin treatment. In conclusion, the results of this study support the effectiveness of warfarin treatment to reduce the rate of stroke in cAF patients in the general clinical practice setting, however the risk reduction is lower than that reported in clinical trials.

Individualizing the risks and benefits of postmenopausal hormone therapy

OBJECTIVE

The objective was to develop an individualized risk-benefit model quantifying the impact of combined use of estrogen and progestogen on chronic diseases.

DESIGN

The study population consisted of women, aged 40+, prescribed postmenopausal hormone therapy (HT) in the UK General Practice Research Database (N > 200,000). Individualized risks of fracture, colorectal cancer, diabetes mellitus, myocardial infarction, deep venous thrombosis/pulmonary embolism, breast cancer, and stroke were estimated using Cox regression. Relative rates from the Women's Health Initiative trial were used to estimate attributable risks (ie, excess risks) in a risk-benefit simulation model.

RESULTS

Risks and benefits increased with age and length of HT use. HT use for 5 years initiated at age 45 increased the absolute risk of myocardial infarction by 0.04% and breast cancer by 0.3% and reduced the risk of hip fracture by 0.03%. Comparably, 5-year HT use started at age 75 led to increases in the risks of myocardial infarction and breast cancer (+0.4% and +0.2%, respectively) and reduced that of hip fracture (-0.9%). There was considerable heterogeneity in the risks and benefits of HT. In most of the younger HT users, the frequency of risks exceeded that of the benefits, although the absolute excess risks were small. In HT users aged 70+, 62.4% experienced more benefits than risks, whereas 37.6% experienced more risks than benefits.

CONCLUSIONS

The frequency of beneficial and adverse effects of HT on chronic diseases was low in younger women, whereas the ratio of these risks and benefits varied substantially among the older users. However, the study could not asses the effects of HT on menopausal symptoms and quality of life, benefits more likely to be observed among younger women.

The importance of the disease process and disease-modifying antirheumatic drug treatment in the development of septic arthritis in patients with rheumatoid arthritis

OBJECTIVE

To evaluate the effect of disease-modifying antirheumatic drugs (DMARDs) on the likelihood of patients with rheumatoid arthritis (RA) developing septic arthritis (SA).

METHODS

The United Kingdom General Practice Research Database (GPRD) was used to identify adults with RA, and age-, sex-, and practice-matched control subjects. Subjects were studied between 1987 and 2002. The risk of developing SA (excluding infected joint replacements) for individuals with RA was calculated and the effect of DMARD use determined.

RESULTS

A total of 136,977 subjects (34,250 patients with RA, 102,747 controls) were identified. SA was identified in 345 subjects, of which 321 (236 in patients with RA, 85 in controls) cases occurred during the study period. The incidence rate of SA was 12.9 times higher in subjects with RA than in those without (95% confidence interval [95% CI] 10.1-16.5, P < 0.001). The incident rate ratios (IRRs) for developing SA while receiving DMARDs compared with receiving no DMARDs were different for different medications. Penicillamine (adjusted IRR 2.51, 95% CI 1.29-4.89, P = 0.004), sulfasalazine (adjusted IRR 1.74, 95% CI 1.04-2.91, P = 0.03), and prednisolone (adjusted IRR 2.94, 95% CI 1.93-4.46, P < 0.001) were associated with an increased incidence of SA when compared with not receiving any DMARD. The use of other DMARDs including methotrexate showed no such effect.

CONCLUSION

Individuals with RA have an increased risk of developing SA. This increased risk can be attributed to both the disease process and the use of DMARDs.

Lithium use and the risk of fractures

A recent study reported a decreased risk of fractures among lithium users. We conducted a case-control study within the UK General Practice Research Database, comparing never, ever, current, recent and past lithium use in 231,778 fracture cases to matched controls. In addition, the risk of fractures was assessed in relation to cumulative duration of use and time since discontinuation. Current use of lithium was associated with a decreased risk of fractures (adjusted odds ratio [OR]=0.75, 95% confidence interval [CI]=0.64-0.88), which did not vary with cumulative duration of use. Among past users an increased risk of fractures was observed (adjusted OR=1.35, 95% CI=1.01-1.79), increasing with time since discontinuation. Our results support the role of the underlying mental disorders in the aetiology of fractures and do not support a pharmacological effect of lithium based on lack of an association with cumulative duration of use.

Update on the epidemiology of Paget's disease of bone

Paget's disease of bone (PDB) is characterized by rapid bone remodeling and the formation of bone that is structurally abnormal. Recent studies have confirmed that both genetic and environmental factors are important in its etiology. Epidemiological studies in Europe and North America have revealed that PDB shows an increasing frequency of occurrence with age and is more prevalent among men than women. There is marked geographic variation in the prevalence of PDB throughout western nations, with the highest rates reported during the 1970s in Britain. Recent studies of the secular trends in PDB suggest declining rates in both prevalence and severity at diagnosis. Thus, the overall age/sex standardized prevalence rate in Britain during the period 1993-1995 was found to be 2.5% among men and 1.6% among women > or = 55 years of age. Prevalence rates had fallen by approximately 50% in several of the centers studied, suggesting an environmental contribution to the etiology of this disorder. Similar findings have been reported from other European countries and New Zealand. Recent study of the incidence and clinical manifestations of PDB have emerged from large cohort studies in primary care record linkage resources, such as the General Practice Research Database. Over the period 1988-1999, the incidence rate of clinically diagnosed PDB was found to be 5 per 10,000 person-years among men and 3 per 10,000 person-years among women 75 years of age. The disorder was associated with an increased risk of back pain (RR, 2.1; 95% CI, 1.9-2.3); osteoarthritis (RR, 1.7; 95% CI, 1.5-1.9); and fracture (RR, 1.2; 95% CI, 1.0-1.5). Using life table methodology, the estimated proportion of patients dying within 5 years of follow-up was 32.7% among the cohort with PDB compared with 28.0% among control patients (p < 0.05).

Risk of Aplastic Anemia in Patients Using Antiepileptic Drugs

PURPOSE

To assess the association between exposure to antiepileptic drugs (AEDs) and the occurrence of aplastic anemia.

METHODS

A retrospective case-control study was conducted using data from the U.K. General Practitioners Research Database (GPRD). Cases were defined as patients diagnosed with aplastic anemia. For each case, up to three control patients were matched on age, sex, and medical practice. Cases and controls were compared with respect to AED use. The effects of duration of AED use were assessed. Characteristics of individual cases with AED use were reviewed.

RESULTS

The study population comprised 173 cases and 497 controls. AED use was more prevalent among cases (9.2%) than among controls (0.8%). After adjustment for confounders, the use of AEDs was significantly associated with aplastic anemia (adjusted odds ratio (OR), 9.5; 95% confidence interval (CI), 3.0-39.7). The most frequently used AEDs were carbamazepine (CBZ), valproic acid (VPA), and phenytoin. The 16 exposed cases were heterogeneous with respect to patient and exposure characteristics: the age of these patients varied from 1 to 92 years, and the duration of AED use varied from 17 days to 6.8 years.

CONCLUSIONS

This study indicates that use of AEDs, in particular CBZ and VPA, is associated with a ninefold increased risk of aplastic anemia. Physicians should be alert to the possibility of AED-associated aplastic anemia.

Risk of hip/femur fractures in patients using antipsychotics

The objective of our study was to investigate whether use of antipsychotics is associated with hip/femur fractures and whether pharmacological differences between antipsychotics are related to the occurrence of fractures. A case-control study was conducted, in which cases were defined as patients with a hip/femur fracture. Each patient was matched to one control patient. The association between use of antipsychotics and the occurrence of hip/femur fractures was evaluated using conditional logistic regression. The study included 44,500 patients from 683 general practices from different geographical areas in the UK, registered within the General Practice Research Database (GPRD). Exposure to antipsychotics was categorized as "no use", "current use" and "prior use". Both current and prior use of antipsychotics were associated with an approximately two-fold increased risk of fractures. After adjustment for possible confounders, a small significant effect remained (Odds Ratios (OR) of 1.3). We did not find an association between dose of antipsychotics, or between the degree of blockade of the alpha-1 adrenoceptor or histamine-1 receptor and risk of fractures. The total number of days of antipsychotic use was significantly associated with an increased risk of hip/femur fractures. We conclude that there is a small increased risk of hip/femur fractures associated with the use of antipsychotics. This risk increases with long-term use.

Epidemiology of childhood fractures in Britain: a study using the general practice research database

A population-based British cohort study, including approximately 6% of the population, was used to derive age- and sex-specific incidence rates of fractures during childhood. Fractures were more common among boys than girls, with peak incidences at 14 and 11 years of age, respectively. At childhood peak, incidence rates were only surpassed later in life at 85 years of age among women and never among men.

INTRODUCTION

Fractures account for 25% of accidents and injuries in childhood; however, the descriptive epidemiology of childhood fractures remains uncertain.

MATERIALS AND METHODS

Age- and sex-specific incidence rates for fractures at various skeletal sites were derived from the General Practice Research Database (a population-based British cohort containing computerized medical records of approximately 7,000,000 residents) between 1988 and 1998.

RESULTS

A total of 52,624 boys and 31,505 girls sustained one or more fractures over the follow-up period, for a rate of 133.1/10,000 person-years. Fractures were more common in boys (161.6/10,000 person-years) than girls (102.9/10,000 person-years). The most common fracture in both sexes was that of the radius/ulna (30%). Fracture incidence was greater among boys than girls at all ages, with the peak incidence at 14 years of age among boys and 11 years of age among girls. Marked geographic variation was observed in standardized fracture incidence, with significantly (p < 0.01) higher rates observed in Northern Ireland, Wales, and Scotland compared with southeast England.

CONCLUSIONS

Fractures are a common problem in childhood, with around one-third of boys and girls sustaining at least one fracture before 17 years of age. Rates are higher among boys than girls, and male incidence rates peak later than those among females. At their childhood peak, the incidence of fractures (boys, 3%; girls, 1.5%) is only surpassed at 85 years of age among women and never among men. The most common site affected in both genders is the radius/ulna. Studies to clarify the pathogenesis of these fractures, emphasizing bone fragility, are now required.