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Biomedical subjects

Alexander M Walker

Publications and source records attributed to Alexander M Walker.

At least 19 recordsLinked to original sources
PubMed2006

Algorithms to identify colonic ischemia, complications of constipation and irritable bowel syndrome in medical claims data: development and validation.

PURPOSE: A challenge in the use of insurance claims databases for epidemiologic research is accurate identification and verification of medical conditions. This report describes the development and validation of claims-based algorithms to identify colonic ischemia, hospitalized complications of constipation, and irritable bowel syndrome (IBS). METHODS: From the research claims databases of a large healthcare company, we selected at random 120 potential cases of IBS and 59 potential cases each of colonic ischemia and hospitalized complications of constipation. We sought the written medical records and were able to abstract 107, 57, and 51 records, respectively. We established a 'true' case status for each subject by applying standard clinical criteria to the available chart data. Comparing the insurance claims histories to the assigned case status, we iteratively developed, tested, and refined claims-based algorithms that would capture the diagnoses obtained from the medical records. We set goals of high specificity for colonic ischemia and hospitalized complications of constipation, and high sensitivity for IBS. RESULTS: The resulting algorithms substantially improved on the accuracy achievable from a naïve acceptance of the diagnostic codes attached to insurance claims. The specificities for colonic ischemia and serious complications of constipation were 87.2 and 92.7%, respectively, and the sensitivity for IBS was 98.9%. CONCLUSIONS: U.S. commercial insurance claims data appear to be usable for the study of colonic ischemia, IBS, and serious complications of constipation.

Algorithms↗
PubMed2006

Cardiovascular risk of selective cyclooxygenase-2 inhibitors and other non-aspirin non-steroidal anti-inflammatory medications.

PURPOSE: The purpose of this study was to estimate rates of acute coronary syndrome (ACS), and sudden cardiac death in relation to use of rofecoxib, celecoxib, naproxen, diclofenac, and ibuprofen. METHODS: We conducted a retrospective cohort study among 424,584 health plan enrollees ages 40-64 who used non-aspirin non-steroidal anti-inflammatory drugs (NANSAIDs) by prescription from 1999 to 2001. We used automated medical and pharmacy claims data to compute person-time exposed to study drugs, and to identify hospitalizations for ACS. The primary endpoint was ACS, inclusive of myocardial infarction (MI), unstable angina, and sudden cardiac death as identified through claims data and confirmed through hospital medical records, or through the National Death Index. RESULTS: Compared with ibuprofen or diclofenac use, the relative risk (RR) of ACS during periods of current rofecoxib use was 1.35 (95%CI 1.09-1.68). For current use of celecoxib, the RR was 1.03 (95%CI 0.83-1.27). Risks in the first 30 days of rofecoxib and celecoxib use were modestly elevated. Rofecoxib use at the 25 mg/day (modal) dose was associated with an elevated risk of ACS (RR 1.54, 95%CI 1.15-2.04), while use at 26-50 mg/day (>modal) was not (RR 0.81, 95%CI 0.41-1.60). There were no increased risks with modal or greater than modal doses of celecoxib or naproxen compared with all doses of ibuprofen or diclofenac combined. CONCLUSIONS: The incidence of ACS was 1.35 times greater during rofecoxib use than use of ibuprofen or diclofenac. No statistically significant elevation in risk was observed with celecoxib use. Naproxen use was not associated with risk of ACS.

Acute Disease↗
PubMed2005

Results of multivariable logistic regression, propensity matching, propensity adjustment, and propensity-based weighting under conditions of nonuniform effect.

Observational studies often provide the only available information about treatment effects. Control of confounding, however, remains challenging. The authors compared five methods for evaluating the effect of tissue plasminogen activator on death among 6,269 ischemic stroke patients registered in a German stroke registry: multivariable logistic regression, propensity score-matched analysis, regression adjustment with the propensity score, and two propensity score-based weighted methods-one estimating the treatment effect in the entire study population (inverse-probability-of-treatment weights), another in the treated population (standardized-mortality-ratio weights). Between 2000 and 2001, 212 patients received tissue plasminogen activator. The crude odds ratio between tissue plasminogen activator and death was 3.35 (95% confidence interval: 2.28, 4.91). The adjusted odds ratio depended strongly on the adjustment method, ranging from 1.11 (95% confidence interval: 0.67, 1.84) for the standardized-mortality-ratio weighted to 10.77 (95% confidence interval: 2.47, 47.04) for the inverse-probability-of-treatment-weighted analysis. For treated patients with a low propensity score, risks of dying were high. Exclusion of patients with a propensity score of <5% yielded comparable odds ratios of approximately 1 for all methods. High levels of nonuniform treatment effect render summary estimates very sensitive to the weighting system explicit or implicit in an adjustment technique. Researchers need to be clear about the population for which an overall treatment estimate is most suitable.

Aged↗
PubMed2005

Determinants of the differences in LDL-cholesterol after initiation of statin treatment.

BACKGROUND: Randomized clinical trials may not accurately predict drug benefit in clinical practice because the patients and conditions of therapy almost always differ between those settings. OBJECTIVE: To determine whether differences in low-density lipoprotein cholesterol (LDL-C) time curves between clinical trial results and usual care experience after initiation of statin therapy could be explained fully in terms of observable characteristics of patients and practice in usual care. METHODS: We compared LDL-C measurements for 3 years after initiation of statin treatment in individuals enrolled in a health maintenance organization (HMO), with enrollees in the active treatment arm of the CARE (Cholesterol and Recurrent Events) trial. Analysis of the determinants of variation in LDL-C in the HMO cohort was used to adjust the crude results to the distribution of patient and treatment characteristics in the trial. RESULTS: The mean percent decrease in LDL-C was lower in the HMO cohort (n = 1245) than in the clinical trial at the end of each 6-month period, with the difference diminishing over time. Adjustment of the HMO time curve to the baseline characteristics of the clinical trial cohort did not significantly change the mean estimates at any time point. Assuming optimal adherence in the HMO cohort raised the curve over time, with 95% confidence intervals including the means observed in CARE after 18 months. Fixing treatment to pravastatin 40 mg/day, as in CARE, brought the estimates in the HMO cohort very close to those of the clinical trial, with 95% confidence intervals including the means observed in CARE at all time points. CONCLUSIONS: Treatment selection, dosing, and adherence under usual care were the primary reasons for which improvements in LDL-C in practice fell short of expectations that are based on clinical trial findings for statin therapy. Beginning with a low dose of statins and titrating to a satisfactory response can delay effective treatment by 18 months or more. Poor adherence accounts for a further substantial shortfall from maximal effect. Differences between trial populations and the general population of statin users with respect to age, gender, and baseline LDL-C have no measurable impact on discrepancies between predicted and observed LDL-C improvement in usual practice.

Adult↗
PubMed2005

Posttransplant lymphoproliferative disorder among renal transplant patients in relation to the use of mycophenolate mofetil.

BACKGROUND: The introduction of increasingly effective immunosuppressants has raised the question of whether posttransplant lymphoproliferative disorder (PTLD), a complication of immunosuppression, would become more frequent. This study assessed the risk of PTLD in relation to immunosuppression during a period that saw the introduction and eventual market dominance of mycophenolate mofetil (MMF). METHODS: A case-control study was conducted at 23 U.S. transplant centers. All participants received a renal-only transplant on or after July 1, 1995. PTLD cases were reported by centers and confirmed by central review. The United Network for Organ Sharing (UNOS) supplemented case ascertainment and identified controls matched on center, transplant date, and age. Center personnel abstracted risk factor and therapy data for cases and up to four controls per case. Cases and controls were compared, using a matched multivariate analysis, to assess the impact of MMF as one component of triple-therapy adjusted for other drug therapies and known risk factors. RESULTS: Data were collected for 108 PTLD cases and 404 controls. PTLD risk for individuals on triple therapy with MMF was similar to the risk experienced by individuals on triple therapy with no MMF (adjusted odds ratio=1.19; 95% CI 0.55-2.55). There was no dose response relationship between MMF and PTLD risk. CONCLUSIONS: Use of MMF was not associated with an increase in PTLD among patients who received triple immunosuppressive therapy, but an excess in risk as large as 155% or a reduction in risk by as much as 45% cannot be ruled out.

Case-Control Studies↗
PubMed2005

An application of propensity score matching using claims data.

BACKGROUND: Confounding by indication is a common problem in pharmacoepidemiology, where predictors of treatment also have prognostic value for the outcome of interest. The tools available to the epidemiologist that can be used to mitigate the effects of confounding by indication often have limits with respect to the number of variables that can be simultaneously incorporated as components of the confounding. This constraint becomes particularly apparent in the context of a rich data source (such as administrative claims data), applied to the study of an outcome that occurs infrequently. In such settings, there will typically be many more variables available for control as potential confounders than traditional epidemiologic techniques will allow. METHODS: One tool that can indirectly permit control of a large number of variables is the propensity score approach. This paper illustrates the application of the propensity score to a study conducted in an administrative database, and raises critical issues to be addressed in such an analysis. In this example, the effect of statin therapy on the occurrence of myocardial infarction was examined, and numerous potential confounders of this association were adjusted simultaneously using a propensity score to form matched cohorts of statin initiators and non-initiators. RESULTS: The incidence of myocardial infarction observed in the statin treated cohort was lower than the incidence in the untreated cohort, and the magnitude of this effect was consistent with results from randomized placebo controlled clinical trials of statin therapy. CONCLUSIONS: This example illustrates how confounding by indication can be mitigated by the propensity score matching technique. Concerns remain over the generalizability of estimates obtained from such a study, and how to know when propensity scores are removing bias, since apparent balance between compared groups on measured variables could leave variables not included in the propensity score unbalanced and lead to confounded effect estimates.

Cohort Studies↗
PubMed2005

Persistence and adherence with topical glaucoma therapy.

PURPOSE: The present study describes the patterns and predictors of treatment persistence and adherence among patients who are diagnosed with glaucoma or as glaucoma suspects (based on claims codes). DESIGN: A retrospective cohort study using health insurance claims data. METHODS: Newly treated individuals with diagnosed glaucoma (n = 3623) and suspect glaucoma (n = 1677) were obtained from healthcare claims data in the Ingenix Research Database. For each of these two diagnostic groups, we calculated the duration of continuous treatment with the initially prescribed medication (persistence) and the prevalence of use of the initial medication at various time points (adherence). Four drug classes were included: beta-blockers, alpha-agonists, carbonic anhydrase inhibitors, and prostaglandin analogs. RESULTS: Nearly one half of the individuals who had filled a glaucoma prescription discontinued all topical ocular hypotensive therapy within six months, and just 37% of these individuals recently had refilled their initial medication at three years after the first dispensing. Prostaglandins were associated with better persistence than any other drug class, which was indicated by hazard ratios for discontinuation of prostaglandins compared with beta-blockers of 0.40 (95% confidence interval, 0.35-0.44) for diagnosed patients and 0.44 (95% confidence interval, 0.37-0.52) for patients with suspect glaucoma. Prostaglandins showed a similar advantage in adherence. Furthermore, patients with diagnosed glaucoma were more likely to adhere to therapy than patients with suspect glaucoma (relative risk = 1.11; 95% confidence interval, 1.05-1.18). CONCLUSION: Persistence and adherence were substantially better with prostaglandins than with other drug classes, and patients with diagnosed open-angle glaucoma were more likely to adhere to treatment than suspected glaucoma.

Administration, Topical↗
PubMed2005

The long-term course of low-density lipoprotein cholesterol after initiation of statin treatment: retrospective database analysis over 3 years in health maintenance organization enrollees.

OBJECTIVES: Our primary objective was to obtain robust estimates of the low-density lipoprotein cholesterol (LDL-C) decrease from baseline over a long period (ie, 3 years) after initiation of statin treatment in a usual-care setting. Our secondary objective was to investigate the predictors of the LDL-C time course. METHODS: We retrospectively analyzed the data for a sample of enrollees in a health maintenance organization (HMO) who started statin treatment between October 1, 1995, and December 31, 1998. Using the HMO's claims database, we examined the LDL-C change from baseline (as measured at the prescribing physicians' discretion) and computed mean estimates every 6 months up to 3 years. We investigated potential predictors of the LDL-C time course (ie, age, sex, baseline LDL-C, previous treatment, prescribing physician's specialty, and most recent treatment) with a mixed model applied to longitudinal data. This model enabled us to impute missing data for all enrollees still being followed, including those who had stopped treatment, and to discuss the robustness of our findings. We applied 2 methods of imputation, assuming either of the following: (1) data were missing at random but could be estimated from the parameters in the mixed model, or (2) LDL-C returned to the baseline value > or =15 days after treatment cessation. RESULTS: We examined data from 3193 individuals. In most cases, the statin used was fluvastatin or pravastatin. The observed mean (95% CI) LDL-C decrease from baseline widened progressively from 23.6% (23.0%-24.3%) at 6 months to 28.0% (27.1%-28.9%) at 18 months and 30.2% (28.7%-31.7%) at 36 months after treatment initiation. These results remained robust after the imputation of missing data, with mean LDL-C reduction consistently >20% at each 6-month time point during the 3 years after treatment initiation. Variations as a function of baseline characteristics were limited (demographics) or explicable by extraneous factors (baseline LDL-C). There were predictable variations as a function of the most recent treatment. CONCLUSIONS: This analysis indicates a long-term reduction in LDL-C among a sample of HMO enrollees who initiated statin treatment in a usual-care setting. The results were robust after imputation of missing data, with mean decrease from baseline consistently >20% over 3 years. However, given the retrospective design of our study and the absence of a control group, we cannot determine how much of the decrease was attributable to treatment.

Aged↗
PubMed2005

Compliance with a statin treatment in a usual-care setting: retrospective database analysis over 3 years after treatment initiation in health maintenance organization enrollees with dyslipidemia.

BACKGROUND: Patients treated in a usual-care setting often do not comply with prescribed treatment regimens as closely as those treated in a clinical trial, for a variety of reasons. OBJECTIVES: We sought to describe compliance over 3 years with a statin treatment in an observational study in a usual-care setting and to investigate potential risk factors for poor compliance. METHODS: Enrollees in a Massachusetts health maintenance organization (HMO) who presented with baseline low-density lipoprotein cholesterol (LDL-C) > or =130 mg/dL and who started statin treatment between January 1, 1994, and July 1, 1999, were followed until death, termination of membership in the HMO, or July 1, 1999, whichever came first, as documented by the HMO's drug-dispensing electronic records. The records included information about the demographics, service dates, laboratory data, and filled prescriptions. The outcome measures were time to treatment discontinuation, time to treatment resumption, and adherence to treatment. RESULTS: A total of 4776 enrollees were included in the analysis. Most patients were aged 50 to 69 years (57%), men (52%), had LDL-C > or =160 mg/dL (77%), and received their prescription for antihyperlipidemia therapy from an internist or family physician (87%). The hazard of discontinuation was high during the first 6 months of therapy, with 20% of the initial population discontinuing treatment during this time period, then decreased, so that the fraction of continuing users leveled off: 74%, 65%, and 61% of statin initiators were still on treatment 1, 2, and 3 years after entry, respectively. The probability of resuming statin treatment was 51% within 24 months after last prescription filled. The proportion of adherent users stayed stable, between 53% and 55%, after the first 6 months. Risk factors of treatment discontinuation, treatment resumption, and adherence were remarkably similar and were stable over time. The significant predictors of treatment discontinuation were age <50 years (hazard ratio [HR], 1.45 [95% Cl, 1.26-1.68]), female sex (HR, 1.18 [95% CI, 1.06-1.30], and previous antihyperlipidemia treatment (HR, 0.71 [95% CI, 0.63-0.79]). CONCLUSIONS: In this HMO setting, women and individuals 1026 aged <50 years were at risk for poor compliance with statin therapy. Our analysis suggests that the association between compliance and age or gender may be quite stable over the first 3 years of treatment.

Age Factors↗
PubMed2005

The risk of nonvertebral fracture related to inhaled corticosteroid exposure among adults with chronic respiratory disease.

OBJECTIVE: To examine nonvertebral fracture risk in relation to inhaled corticosteroid (ICS) exposure among adults with respiratory disease. DESIGN AND PATIENTS: Nested case-control study within a cohort of 89,877 UnitedHealthcare members aged > or = 40 years with physician insurance claims for COPD or asthma, enrolled for > or = 1 year from January 1, 1997 to June 30, 2001. METHODS: Cases (n = 1,722) represented patients with a first treated nonvertebral fracture (the index date is the first fracture claim). Control subjects (n = 17,220) were randomly selected from the person-time and assigned a random index date. ICS exposure was ascertained 1 month, 3 months, 6 months, and 12 months before the index date, with estimated cumulative dose through 0 to 6 months, 7 to 12 months, and 0 to 12 months. Covariates included demographics, oral corticosteroid and other medication exposure, comorbidities, and indicators of respiratory disease severity. Odds ratios (ORs) adjusted for all covariates were estimated by logistic regression. RESULTS: No increased fracture risk with ICS exposure as a class or with fluticasone propionate alone was detected. ORs for exposure in the preceding 30 days were 1.05 (95% confidence interval [CI], 0.89 to 1.24), 1.13 (95% CI, 0.90 to 1.40), and 0.97 (95% CI, 0.78 to 1.21) for all ICS, fluticasone propionate, and other ICS, respectively. No dose-response effect was present. Among patients with COPD only (n = 6,932), no increased risk was found for recent ICS exposure (OR, 0.86; 95% CI, 0.59 to 1.25). CONCLUSIONS: Concern about nonvertebral fracture risk should not strongly influence the decision to use recommended doses of ICS for adult patients with asthma or COPD in managed-care settings in the United States. This study could not evaluate very-high ICS dose, long-term ICS exposure, or vertebral fracture risk.

Adult↗
PubMed2004

Benzodiazepine use and hip fractures in the elderly: who is at greatest risk?

BACKGROUND: It remains unclear whether benzodiazepine use increases hip fracture incidence. We studied this relationship in a large cohort, controlling for multiple potential confounders. METHODS: We analyzed 42 months of New Jersey Medicaid health care claims data for all enrollees. Each eligible person-day was assigned to categories of benzodiazepine exposure and categories of other predictors, based on prior and current medication dispensing and diagnosis information. Hip fractures were identified based on hospital claims with primary discharge diagnosis International Classification of Diseases, Ninth Revision (ICD-9) codes 820.xx. RESULTS: Cohort members (n = 125 203) contributed 194 071 person-years and had 2312 eligible hip fractures. After adjustment for age, sex, race, Medicaid nursing home residence, exposure to other psychoactive medications, including antiparkinsonian medications, diagnoses of epilepsy and dementia, and hospitalization in the previous 6 months, the incidence rate of hip fracture was significantly higher compared with no benzodiazepine use for exposure to any benzodiazepine (incidence rate ratio [IRR], 1.24; 95% confidence interval [CI], 1.06-1.44), to a short half-life, high-potency benzodiazepine (IRR, 1.27; 95% CI, 1.01-1.59), during the first 2 weeks after starting a benzodiazepine (IRR, 2.05; 95% CI, 1.28-3.28), during the second 2 weeks after starting a benzodiazepine (IRR, 1.88; 95% CI, 1.15-3.07), and for continued use (IRR, 1.18; 95% CI, 1.03-1.35). CONCLUSIONS: The incidence of hip fracture appears to be associated with benzodiazepine use. Contrary to several previous studies, short half-life benzodiazepines are not safer than long half-life benzodiazepines. Hip fracture risk is highest during the first 2 weeks after starting a benzodiazepine and declines thereafter.

Aged↗
PubMed2004

Incidence of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome.

BACKGROUND: Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are rare disorders characterized by platelet aggregation, microthrombi, and resulting tissue damage. We studied the incidence and possible risk factors for these diseases in 3 large populations in the United States, United Kingdom, and Canada. METHODS: Data were derived from a large health insurer in the United States, general practices in the United Kingdom, and the Province of Saskatchewan. We identified potential cases of thrombotic thrombocytopenia purpura and hemolytic uremic syndrome in computerized data and verified them by medical record review. We estimated incidence rates for thrombotic thrombocytopenia purpura and hemolytic uremic syndrome together and separately, and we conducted a case-control study to evaluate potential risk factors. RESULTS: The age-sex standardized incidence of thrombotic thrombocytopenia purpura and hemolytic uremic syndrome was higher than previously reported (6.5, 2.2, and 3.2 per million per year in the United States, United Kingdom, and Saskatchewan, respectively), but there was no secular trend. The incidence of thrombotic thrombocytopenia purpura and hemolytic uremic syndrome was higher in women than men. Most cases of hemolytic uremic syndrome occurred before 20 years of age. We confirmed several known risk factors for thrombotic thrombocytopenia purpura and hemolytic uremic syndrome (cancer, bone marrow transplantation, pregnancy). CONCLUSION: The incidence of thrombotic thrombocytopenia purpura and hemolytic uremic syndrome is higher than previously reported but does not appear to be rising. Apparent international differences in incidence could be the result of imprecision in identifying thrombotic thrombocytopenia purpura and hemolytic uremic syndrome in large research databases.

Adult↗
PubMed2004

Serious cardiovascular events and mortality among patients with schizophrenia.

This study compared the risks of cardiovascular morbidity and mortality in people with schizophrenia who use antipsychotic medications to risks in individuals without schizophrenia in a large managed care organization. A sample of 1920 schizophrenia patients was matched by age, sex, date, and health plan to 9600 persons randomly selected from the health plan general membership. Death, myocardial infarction, arrhythmia, and new-onset diabetes were identified using a National Death Index search and medical claims records. The adjusted all-cause mortality rate in the group of treated schizophrenics was four times higher than in the control group regardless of whether patients were given a typical or an atypical antipsychotic medication. Users of typical antipsychotics had a fivefold higher risk of myocardial infarction than the control subjects. Among patients with schizophrenia, cardiovascular risk was inversely associated with intensity of use of antipsychotic drugs, suggesting that the observed risks may not be due to a simple or direct effect of drugs. Patients treated for schizophrenia had higher rates of new-onset diabetes than did the general population controls. This risk was most pronounced in persons with more intense exposure to drugs and appeared to be indistinguishable in users of typical antipsychotics, of atypical products, or of both.

Adult↗
PubMed2004

Occurrence of colon ischemia in relation to irritable bowel syndrome.

OBJECTIVE: In November 2000, alosetron HCl (Lotronex), a treatment for irritable bowel syndrome (IBS), was removed from the U.S. market in part because of the occurrence of colon ischemia in treated patients. Since the relation between colon ischemia and IBS is poorly understood, we evaluated the incidence of colon ischemia among people with and without IBS. METHODS: Using medical claims data from a large health care organization in the United States, we identified 87,449 people with an IBS diagnosis between January 1995 and December 1999. We calculated age- and sex-specific incidence rates in the general population and in IBS patients. RESULTS: There were 740 cases of colon ischemia during 8.5 million person-years of observation in 5.4 million persons. The crude incidence rate was 42.8 cases per 100,000 person-years for IBS patients. By comparison, the incidence rate was 7.2 per 100,000 person-years in the general population. After adjustment for age, sex, and calendar year, the incidence of colon ischemia in people with IBS was 3.4 times higher than in persons without (95% CI 2.6-4.5). CONCLUSIONS: Rates of colon ischemia among patients carrying a diagnosis of IBS are substantially higher than in the general population. Colon ischemia, though unusual in IBS patients, may nonetheless constitute a distinct part of the IBS natural history. Alternatively, it may be a consequence of therapy, or a manifestation of other bowel pathology that is sometimes confused with IBS.

Adult↗
PubMed2004

Risk factors for colon ischemia.

BACKGROUND: To identify predictors of colon ischemia, we examined demographic and clinical characteristics of patients, as well as their prior health care utilization. METHODS: Using insurance data, we identified 700 persons at least 20-yr old with presumed colon ischemia between 1995 and 1999, and 6,440 controls. Case identification was based on diagnosis and procedure codes in insurance claims for which we used a previously reported, validated algorithm. We ascertained preceding medical diagnoses and the use of drugs and health services from the insurance claims files. RESULTS: Patients with colon ischemia were nearly three times as likely to have IBS than controls. A history of nonspecific colitis, lower gastrointestinal tract hemorrhage, systemic rheumatologic disorders, and ischemic heart disease in the preceding 6 months, and abdominal surgery in the past month were also much more common in colon ischemia cases than controls. Use of a drug to treat diarrhea was strongly associated with risk. The most prevalent risk factor for colon ischemia was the use of drugs with a side effect of constipation, found in one-third of cases and one in nine controls. Cases had seen physicians, particularly gastroenterologists, much more commonly in the preceding 6 months than had controls. CONCLUSIONS: Clinically evident colon ischemia arises preferentially in persons with prior abdominal complaints, many of whom carry a diagnosis of IBS. Drugs that reduce bowel motility may constitute a widespread and potentially avoidable risk factor. The frequency of preceding doctor visits, without a specific diagnosis, suggests that colon ischemia may have a prolonged subacute presentation.

Adult↗
PubMed2003

A propensity score-matched cohort study of the effect of statins, mainly fluvastatin, on the occurrence of acute myocardial infarction.

This investigation quantified the effect of statins on acute myocardial infarction (AMI) in an observational setting where fluvastatin represented most of the statin use. The study applied propensity scores to match statin initiators to statin noninitiators and followed them for the occurrence of AMI. Serum low-density lipoprotein levels were reduced by statin therapy, and there were fewer incidents of AMI in statin initiators than in noninitiators.

Cholesterol, LDL↗
PubMed2003

Inhibition of clinical benefits of aspirin on first myocardial infarction by nonsteroidal antiinflammatory drugs.

BACKGROUND: There is clear evidence from numerous randomized trials and their meta-analyses that aspirin reduces risks of first myocardial infarction (MI). Recent data also suggest that other nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with this benefit of aspirin. METHODS AND RESULTS: We performed subgroup analysis from a 5-year randomized, double-blind, placebo-controlled trial of 325 mg aspirin on alternate days among 22 071 apparently healthy US male physicians with prospective observational data on use of NSAIDs. A total of 378 MIs were confirmed, 139 in the aspirin group and 239 in the placebo group. Aspirin conferred a statistical extreme (P<0.00001) 44% reduction in risk of first MI. Among participants randomized to aspirin, use of NSAIDs on 1 to 59 d/y was not associated with MI (multivariable adjusted relative risk [RR], 1.21; 95% confidence interval [CI], 0.78 to 1.87), whereas the use of NSAIDs on > or =60 d/y was associated with MI (RR, 2.86; 95% CI, 1.25 to 6.56) compared with no use of NSAIDs. In the placebo group, the RRs for MI across the same categories of NSAID use were 1.14 (95% CI, 0.81 to 1.60) and 0.21 (95% CI, 0.03 to 1.48). CONCLUSIONS: These data suggest that regular but not intermittent use of NSAIDs inhibits the clinical benefits of aspirin. Chance, bias, and confounding remain plausible alternative explanations, despite the prospective design and adjustment for covariates. Nonetheless, we believe the most plausible interpretation of the data to be that regular but not intermittent use of NSAIDs inhibits the clinical benefit of aspirin on first MI.

Adult↗