Impact of allopurinol on risk of myocardial infarction.

BACKGROUND: Gout therapy includes xanthine oxidase inhibitors (XOI) and colchicine, which have both been associated with decreased cardiovascular risk. However, their effects on major cardiac events, such as myocardial infarction (MI), need to be investigated further. OBJECTIVES: To investigate whether XOIs and colchicine are associated with decreased risk of MI. METHODS: This case-control study compared patients with first-ever MI and matched controls. Cases were recruited from the Pharmacoepidemiological General Research on MI registry. Controls were selected from a referent population (n=8444) from general practice settings. RESULTS: The study sample consisted of 2277 MI patients and 4849 matched controls. Use of allopurinol was reported by 3.1% of cases and 3.8 of controls, and 1.1% of cases and controls used colchicine. The adjusted OR (95% CI) for MI with allopurinol use was 0.80 (0.59 to 1.09). When using less stringent matching criteria that allowed for inclusion of 2593 cases and 5185 controls, the adjusted OR was 0.73 (0.54 to 0.99). Similar results were found on analysis by sex and hypertension status. Colchicine used was not associated with a decreased risk of MI (aOR=1.17 (0.70 to 1.93)). CONCLUSIONS: Allopurinol may be associated with a reduced risk of MI. No decreased risk of MI was found in colchicine users. Besides its urate-lowering property, allopurinol might have a cardioprotective effect.

Autoimmune disorders and quadrivalent human papillomavirus vaccination of young female subjects.

OBJECTIVES: The aim of this study was to investigate whether the quadrivalent human papillomavirus (HPV) vaccine Gardasil is associated with a change in the risk of autoimmune disorders (ADs) in young female subjects. DESIGN: Systematic case-control study of incident ADs associated with quadrivalent HPV vaccination in young women across France. PARTICIPANTS AND SETTING: A total of 113 specialised centres recruited (from December 2007 to April 2011) females aged 14-26 years with incident cases of six types of ADs: idiopathic thrombocytopenic purpura (ITP), central demyelination/multiple sclerosis (MS), Guillain-Barré syndrome, connective tissue disorders (systemic lupus erythematosus, rheumatoid arthritis/juvenile arthritis), type 1 diabetes mellitus and autoimmune thyroiditis. Control subjects matched to cases were recruited from general practice. ANALYSIS: Multivariate conditional logistic regression analysis; factors included age, geographical origin, smoking, alcohol consumption, use of oral contraceptive(s) or vaccine(s) other than Gardasil received within 24 months before the index date and personal/family history of ADs. RESULTS: Overall, 211 definite cases of ADs were matched to 875 controls. The adjusted odds ratio (OR) for any quadrivalent HPV vaccine use was 0.9 [95% confidence interval (CI) 0.5-1.5]. The individual ORs were 1.0 (95% CI 0.4-2.6) for ITP, 0.3 (95% CI 0.1-0.9) for MS, 0.8 (95% CI 0.3-2.4) for connective disorders and 1.2 (95% CI 0.4-3.6) for type 1 diabetes. No exposure to HPV vaccine was observed in cases with either Guillain-Barré syndrome or thyroiditis. CONCLUSIONS: No evidence of an increase in the risk of the studied ADs was observable following vaccination with Gardasil within the time periods studied. There was insufficient statistical power to allow conclusions to be drawn regarding individual ADs.

Misconceptions about transmission of AIDS and attitudes toward prevention in the French general public.

A survey of the social perception of AIDS and its prevention was carried out in December 1987 in a representative sample of the adult population of the Paris region (France). A significant part of the general public still holds misconceptions about transmission by casual contact and blood donation. Misbeliefs about modes of transmission clearly encourage individuals' willingness to stigmatize AIDS patients and to support the most coercive measures of prevention (such as quarantine). Advertizing efforts to promote use of condoms, sexual education in schools, and systematic HIV screening for pregnant women are the only measures which create a broad consensus independently of sociocultural differences. Socioeconomic status and even religious or political beliefs strongly influence public opinions toward other preventive measures.

Use of oral corticosteroids and risk of fractures.

Treatment with oral corticosteroids is known to decrease bone density but there are few data on the attendant risk of fracture and on the reversibility of this risk after cessation of therapy. A retrospective cohort study was conducted in a general medical practice setting in the United Kingdom (using data from the General Practice Research Database [GPRD]). For each oral corticosteroid user aged 18 years or older, a control patient was selected randomly, who was matched by age, sex, and medical practice. The study comprised 244,235 oral corticosteroid users and 244,235 controls. The average age was 57.1 years in the oral corticosteroid cohort and 56.9 years in the control cohort. In both cohorts 58.6% were female. The most frequent indication for treatment was respiratory disease (40%). The relative rate of nonvertebral fracture during oral corticosteroid treatment was 1.33 (95% confidence interval [CI], 1.29-1.38), that of hip fracture 1.61 (1.47-1.76), that of forearm fracture 1.09 (1.01-1.17), and that of vertebral fracture 2.60 (2.31-2.92). A dose dependence of fracture risk was observed. With a standardized daily dose of less than 2.5 mg prednisolone, hip fracture risk was 0.99 (0.82-1.20) relative to control, rising to 1.77 (1.55-2.02) at daily doses of 2.5-7.5 mg, and 2.27 (1.94-2.66) at doses of 7.5 mg or greater. For vertebral fracture, the relative rates were 1.55 (1.20-2.01), 2.59 (2.16-3.10), and 5.18 (4.25-6.31), respectively. All fracture risks declined toward baseline rapidly after cessation of oral corticosteroid treatment. These results quantify the increased fracture risk during oral corticosteroid therapy, with greater effects on the hip and spine than forearm. They also suggest a rapid offset of this increased fracture risk on cessation of therapy, which has implications for the use of preventative agents against bone loss in patients at highest risk.

Multiple sclerosis and antecedent infections: a case-control study.

OBJECTIVES: To determine whether there is an excess of respiratory tract infections in the 5-week, 3-month, and 12-month periods before MS symptom onset and if there is an association between MS and a history of infectious mononucleosis (IM). BACKGROUND: The etiology of MS remains unknown, but infection is frequently suggested as a putative etiologic agent. Epidemiologic studies have produced inconsistent evidence for an etiologic role of respiratory tract infections (RTI) and IM in MS. METHODS: The authors performed a case-control study using the General Practice Research Database from the United Kingdom. There were 225 subjects with definite or probable MS, and 900 controls matched for age, sex, and physician practice. Using computerized patient records, the authors compared the mean rates of RTI per patient in the 5-week, 3-month, and 12-month periods before the date of onset of the first symptoms compatible with MS (index date). They also compared histories of IM. RESULTS: In all periods, an increased frequency of RTI was associated with a significantly increased risk of MS. A history of IM was associated with greater than five times the risk of MS (OR = 5.5 [95% CI 1.5 to 19.7]). CONCLUSIONS: These results support an association between a history of IM and subsequent MS. Respiratory tract infections may precipitate disease onset.

The influence of venous thromboembolism on quality of life and severity of chronic venous disease.

BACKGROUND: It is not known whether burden-of-illness differs in chronic venous disease patients with prior venous thromboembolism compared with patients with other forms of chronic venous disease. OBJECTIVE: To compare severity of disease and quality of life in chronic venous disease patients with and without prior venous thromboembolism. PATIENTS AND METHODS: The VEINES Study population is an international cohort of 1531 outpatients with chronic venous disease in Belgium, France, Italy and Canada. Clinical severity of chronic venous disease graded using the seven-category 'CEAP' scale, and quality of life using standardized generic (SF-36) and venous disease-specific (VEINES-QOL/Sym) questionnaires were compared in patients with and without venous thromboembolism. Multivariable analyses with adjustment for known confounders were used to examine associations between venous thromboembolism and quality of life. RESULTS: One hundred and fifty-one (10%) patients had prior venous thromboembolism. These patients had more severe chronic venous disease than those without venous thromboembolism (P <0.0001), including a higher frequency of healed or active ulcers (29% vs. 7%, respectively). Multivariable analyses controlling for age, sex, country, education, body mass index, years of chronic venous disease and comorbid conditions demonstrated that prior venous thromboembolism was an independent predictor of poorer generic quality of life (SF-36 Mental Component Summary score, P=0.047; SF-36 Physical Component Summary score, P=0.012) and venous disease-specific quality of life (VEINES-QOL, P = 0.0002; VEINES-Sym, P=0.009). CONCLUSIONS: Disease severity is worse and quality of life poorer in chronic venous disease patients with prior venous thromboembolism compared with patients with other forms of chronic venous disease. Our findings support the need for further research of interventions to prevent and treat the long-term complications of venous thromboembolism.

Upper gastrointestinal adverse events and cyclical etidronate.

PURPOSE: Recently, there have been several published case reports of esophagitis associated with the use of aminobisphosphonates. The objective of this study was to evaluate the upper gastrointestinal (GI) safety of cyclical etidronate, an alkylbisphosphonate, in routine clinical practice. PATIENTS AND METHODS: Information was obtained from 550 general practices in the United Kingdom that provide the medical records to the General Practice Research Database. A group of 7977 cyclical etidronate takers and 2 age-, gender-, and practice-matched control groups (1 with osteoporosis and 1 without) were analyzed. RESULTS: For cyclical etidronate takers, the average age was 71.6 years and total follow-up was 10,328 person-years. The risk of upper GI events (inflammation or ulcer of esophagus, stomach, or duodenum) was comparable between patients taking etidronate and the two control groups. The adjusted relative risk of upper GI events was 0.92 (95% confidence interval [CI] 0.78 to 1.09) for etidronate takers compared with osteoporosis controls and 1.12 (CI 0.91 to 1.37) compared to nonosteoporosis controls. For esophagitis and esophageal ulcers, the relative risks were 0.83 (CI 0.64 to 1.08) and 0.97 (CI 0.71 to 1.31) respectively. The incidence of upper GI events during nonsteroidal anti-inflammatory drug (NSAID), aspirin, or corticosteroid use was similar across the three groups. The upper GI risks of etidronate NSAID users were 0.71 (CI 0.45 to 1.11) and 2.06 (CI 0.98 to 4.35) compared with NSAID users in the two control groups. CONCLUSIONS: These results support the GI tolerability and safety profile of cyclical etidronate in routine clinical practice. Concomitant use of cyclical etidronate with NSAIDs, aspirin, or corticosteroids did not increase the incidence of upper GI events.

Clinical prediction of deep vein thrombosis in patients with leg symptoms.

Symptoms and clinical signs individually are inaccurate for the diagnosis of DVT. However, when assessing patients with leg symptoms, clinicians have access to additional information, such as whether or not DVT risk factors are present that could improve the accuracy of clinical judgment. The purpose of this study was to identify which clinical variables best predict DVT, and to use these variables to create a clinical prediction index for DVT. We studied 271 university hospital patients with a first episode of symptomatic, clinically suspected DVT. The prevalence of DVT was 27%, of which 71% were proximal. At baseline, information was collected on demographic features, comorbidity, and symptoms and signs. A Bayesian model selection strategy was used to estimate the logistic regression model that best predicted DVT. Male sex [OR = 2.8 (1.5, 5.1)], orthopedic surgery [OR = 5.4 (2.2, 13.6)], warmth [OR = 2.1 (1.2, 3.9)] and superficial venous dilation on exam [OR = 2.9 (1.4, 5.7)] were independent predictors of DVT. Using the model, a clinical prediction index that categorized patients into different levels of DVT risk was created, and was useful in a theoretical strategy aimed to limit the need for contrast venography in patients with suspected DVT, such that 96% of study patients could have avoided contrast venography. This index should be evaluated prospectively in other patient populations.

Evidence of the depletion of susceptibles effect in non-experimental pharmacoepidemiologic research.

Past experience with a drug may modify the risk of adverse event associated with current use of this drug. This effect was investigated empirically with a study on non-steroidal anti-inflammatory drugs (NSAIDs)-gastropathy. A hospital-based case-control study was conducted with 244 cases of upper gastrointestinal bleeding (UGIB) age 68 and over and 615 matched controls. Data on all medications dispensed to the study patients during the 3 years preceding admission were obtained from the Quebec universal prescription program automated database. Recent use (within 30 days prior to admission) of non-aspirin NSAIDs increased the risk of UGIB. The estimate of relative risk (RR) was 3.4 (CI, 2.1-5.5). Use of NSAIDs in the previous 3 years was associated with a lower risk of UGIB; the estimate of RR was 0.7 (CI, 0.4-1.0). The estimate of RR for first-time users was 22.7 (2.8-200.0) vs 3.0 (1.9-4.7) for those who had used the drugs at least once in the past 3 years. These results provide empirical evidence of a depletion of susceptibles effect whereby patients who remain on the drugs are those who can tolerate them while those who are susceptible select themselves out of the population at risk. Thus, past use should be considered as a potential risk modifier in non-experimental risk assessment of events associated with drug use.

Study of civilian victims of terrorist attacks (France 1982-1987).

The medical and psychological consequences of terrorism were assessed through an epidemiologic survey of 254 survivors of terrorist attacks (TA) that occurred in public places in France between 1982 and 1987 (20 bombings and 1 machine-gun attack). Physical lesions were typical of bombings (blast syndrome, burn, coma), but amputations were rare. Post-traumatic stress disorder (PTSD) was present in 10.5% of uninjured victims, 8.3% of moderately injured and 30.7% of severely injured ones. Major depression was found in 13.3% of all victims, with no difference according to the level of the injury. Prevalence rates were not different in males and females, nor did they vary with age of the victim. The prevalence of PTSD was not associated with the delay between TA and questionnaire completion. These findings suggest the need for including psychiatric assistance in the initial care of TA victims, especially severely injured ones.

Rates of hypoglycemia in users of sulfonylureas.

OBJECTIVE: To identify the demographic and clinical characteristics of sulfonylurea users. To assess the risk of hypoglycemia in patients treated with sulfonylureas in clinical practice, and to characterize the risk in relation to the different drugs used. RESEARCH DESIGN AND METHODS: A cohort of 33,243 sulfonylurea users chosen from 719 clinical practices in the United Kingdom were identified through the VAMP-Research database. Information on demographic characteristics, medical diagnoses and use of medical services was obtained through the computerized records. For a stratified sample of 500 patients, general practioners completed a structured questionnaire on the duration, treatment, and complications of diabetes mellitus, obesity, alcohol use, and smoking history. Patients with a diagnosis of hypoglycemia, as recorded in the database within a time-window of a sulfonylurea prescription, were identified. Incidence rates per person-year of sulfonylurea therapy were estimated. RESULTS: Other than a longer duration of diabetes in users of chlorpropamide, no differences were observed among users of different sulfonylurea agents with respect to diabetic complications, adequacy of diabetic control, obesity, smoking, and excessive alcohol consumption. A diagnosis of hypoglycemia during sulfonylurea therapy was recorded in 605 people over 34,052 person-years of sulfonylurea therapy, which converted into an annual risk of 1.8%. The risk in glibenclamide users was higher than in users of other types of sulfonylureas uses. Duration of therapy, concomitant use of insulin, sulfonylurea-potentiating or antagonizing and concomitant use of beta-blockers were predictive of the risk of developing hypoglycemia. DISCUSSION: Drug use patterns showed comparability among users of different sulfonylurea agents. Our findings suggest that the rate of diagnosis of hypoglycemia made by physicians is higher for glibenclamide than for other sulfonylureas. An epidemiological study with objectively diagnosed hypoglycemia should be undertaken to confirm these results.

A study of the effects of exposure misclassification due to the time-window design in pharmacoepidemiologic studies.

This paper considers the effects of the time-window design on the validity of risk estimates in record linkage studies. A time-window constitutes the number of exposure days assigned to each prescription, often fixed time-intervals. Prescription information was drawn from 36 Dutch pharmacies. Persons, assuming full compliance to the dosage regimen, used NSAIDs during 58% of the 30 day window time (31% with 90 day window). This proportion ranged from 51 to 81% for different NSAIDs; from 75% for elderly to 35% for younger persons. We observed with longer windows a substantive attenuation of incidence rates of peptic ulcer therapy. Simulations also showed that the assignment of equal windows to groups with different durations of drug use can bias risk comparisons, either away from the null or towards the null. We concluded that the choice of prescription time-windows can influence the estimates of exposure risks. Time-windows should cover the period with potential excess risk and be validated.

Sample size calculations for single group post-marketing cohort studies.

In pharmacoepidemiology, single group cohort is the most frequently proposed design to determine if the incidence rate of an adverse drug reaction among the exposed differs from a reference value. In many situations, the number of events expected in the cohort is too small to conduct sample size calculations based on the normal distribution. This paper proposes, for a single group cohort study, calculations and tables derived from the Poisson distribution. The results are based on a one-sided test with a 0.05 significance level and a power of 0.9 and 0.8. Two parameters have to be specified a priori: the expected incidence of the event under the null hypothesis and the minimum risk ratio to be detected. The required sample size and the critical number of events to reject the null hypothesis are directly derived from the tables. Results show that the normal approximation may lead to an underestimation of the required sample size.

The Quebec Back Pain Disability Scale: conceptualization and development.

The Quebec Back Pain Disability Scale is a new measure of functional disability for patients with back pain. Functional disability was operationalized in terms of perceived difficulty associated with simple physical activities. The content of the scale was developed in several stages, including a literature review, two studies seeking the opinions of patients and experts, pilot testing, and a large, longitudinal study of back pain patients. Forty-eight disability items were extensively studied using standard methods such as test-retest reliability, item-total correlations, and factor analysis, as well as modern techniques based on item response theory. Items that were highly effective in discriminating between different levels of disability were selected for the final, reduced scale. The scale has 20 items, representing six empirically derived categories of activities affected by back pain. Measurement properties of this instrument have been previously discussed.

Anorexigens and pulmonary hypertension in the United States: results from the surveillance of North American pulmonary hypertension.

BACKGROUND: The use of appetite suppressants in Europe has been associated with the development of primary pulmonary hypertension (PPH). Recently, fenfluramine appetite suppressants became widely used in the United States but were withdrawn in September 1997 because of concerns over adverse effects. MATERIALS AND METHODS: We conducted a prospective surveillance study on patients diagnosed with pulmonary hypertension at 12 large referral centers in North America. Data collected on patients seen from September 1, 1996, to December 31, 1997, included the cause of the pulmonary hypertension and its severity. Patients with no identifiable cause of pulmonary hypertension were classed as PPH. A history of drug exposure also was taken with special attention on the use of antidepressants, anorexigens, and amphetamines. RESULTS: Five hundred seventy-nine patients were studied, 205 with PPH and 374 with pulmonary hypertension from other causes (secondary pulmonary hypertension [SPH]). The use of anorexigens was common in both groups. However, of the medications surveyed, only the fenfluramines had a significant preferential association with PPH as compared with SPH (adjusted odds ratio for use > 6 months, 7.5; 95% confidence interval, 1.7 to 32.4). The association was stronger with longer duration of use when compared to shorter duration of use and was more pronounced in recent users than in remote users. An unexpectedly high (11.4%) number of patients with SPH had used anorexigens. CONCLUSION: The magnitude of the association with PPH, the increase of association with increasing duration of use, and the specificity for fenfluramines are consistent with previous studies indicating that fenfluramines are causally related to PPH. The high prevalence of anorexigen use in patients with SPH also raises the possibility that these drugs precipitate pulmonary hypertension in patients with underlying conditions associated with SPH.

Determinants of initiation and suboptimal use of anti-ulcer medication: a study of the Quebec older population.

OBJECTIVES: To describe the use of anti-ulcer medication in the Quebec older population; to examine determinants of initiation, suboptimal use, and switches between products. DESIGN: Population-based retrospective cohort study. SETTING: Universal health program for older adults in Quebec. PARTICIPANTS: 5000 users and 5000 non-users of anti-ulcer medications were selected randomly. Use was defined as the presence in the 1991 prescription database of an anti-ulcer prescription. Among users, 1697 (34%) were new users and were considered as the exposure group. Subjects were followed for 365 days after inclusion. MEASUREMENTS: Measured were patient's age, gender, prescribed duration of anti-ulcer medication, concomitant medications, and gastrointestinal diagnostic procedures. RESULTS: A total of 17% of new users had unusually short courses; 18% were long-term users. There was no difference in duration for omeprazole compared with other anti-ulcer medications. First-time use of NSAIDs was the strongest predictor of initiation of anti-ulcer medication (odds ratio = 3.21; 95% CI, 2.66-3.88). Twenty-six percent of users switched brands. Only 9.5% of new users underwent a diagnostic procedure before initiation of therapy, and 49% of long-term users ever underwent such procedure. CONCLUSION: Despite a relatively homogeneous recommended duration of therapy, patterns of use of anti-ulcer medication among older people are highly variable, and treatment is often not accompanied by a diagnostic procedure.

Use of oral corticosteroids in the United Kingdom.

Administration of oral corticosteroids is associated with the development of osteoporosis and an increased risk of fractures. However, the size of the treated sub-population who would benefit from preventive therapy remains uncertain. The objective of this study was to investigate the usage pattern of oral corticosteroids in a large sample representative of the general population in England and Wales. Information was obtained from the General Practice Research Database (GPRD) which contains medical records of general practitioners. Oral corticosteroid users were patients aged 18 years or older who received one or more prescriptions for oral corticosteroids. Over 1.6 million oral corticosteroid prescriptions were issued to the cohort of 244 235 oral corticosteroid users. At any point in time, oral corticosteroids were being used by 0.9% of the total adult GPRD population. The highest use (2.5%) was by people between 70 and 79 years of age. Respiratory disease was the most frequently recorded indication for oral corticosteroid treatment (40%). Patients with arthropathies were most likely to use long-term, continuous treatment, and patients with chronic obstructive pulmonary disease least likely (19.3% and 6.1%, respectively, used oral corticosteroids for more than 2 years). The overall use of bone-active medication (oestrogens, bisphosphonates, vitamin D, and calcitonin) during oral corticosteroid treatment was low (between 4.0% and 5.5%). The current population in the UK at risk of developing corticosteroid-induced fractures might be as large as 350 000. Identification of these patients will be important for implementing preventive strategies in a cost-effective manner.

Postmarketing surveillance of the safety of cyclic etidronate.

To evaluate the safety of cyclic etidronate in routine clinical practice, we obtained information from 550 general practices in the United Kingdom that provide the medical records to the General Practice Research Database. A group of 7977 patients taking cyclic etidronate and two age-, gender-, and practice-matched control groups, one with osteoporosis and one without, were analyzed. For the group taking cyclic etidronate, the average age was 71.6 years and follow-up was 10,328 person-years. Conditions that do not induce osteoporosis generally occurred in these patients at a rate comparable to that in the control groups. The incidence of osteomalacia was low and comparable between patients taking cyclic etidronate and controls with osteoporosis. No medically significant increases in frequency were observed among patients taking cyclic etidronate for a broad group of diseases that may potentially be induced by exposure to the drug. These data support the favorable risk:benefit ratio of cyclic etidronate.