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Biomedical subjects

Mahyar Etminan

Publications and source records attributed to Mahyar Etminan.

At least 19 recordsLinked to original sources
PubMed2006

Reduction of morbidity and mortality by statins, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers in patients with chronic obstructive pulmonary disease.

OBJECTIVES: The purpose of this study was to determine if statins (hydroxymethylglutaryl CoA reductase inhibitors [HMG-CoA]), angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor blockers (ARBs) reduce cardiovascular (CV) events and pulmonary morbidity in chronic obstructive pulmonary disease (COPD) patients. BACKGROUND: Few current COPD therapies alter prognosis. Although statins, ACE inhibitors, and ARBs improve outcomes in CV populations, their benefits in COPD patients both with and without concomitant heart disease has not previously been studied. METHODS: A time-matched nested case-control study of two population-based retrospective cohorts was undertaken: 1) COPD patients having undergone coronary revascularization (high CV risk cohort); and 2) COPD patients without previous myocardial infarction (MI) and newly treated with nonsteroidal anti-inflammatory drugs (low CV risk cohort). Prespecified outcomes were COPD hospitalization, MI, and total mortality. RESULTS: These drugs reduced both CV and pulmonary outcomes, with the largest benefits occurring with the combination of statins and either ACE inhibitors or ARBs. This combination was associated with a reduction in COPD hospitalization (risk ratio [RR] 0.66, 95% confidence interval [CI] 0.51 to 0.85) and total mortality (RR 0.42, 95% CI 0.33 to 0.52) not only in the high CV risk cohort but also in the low CV risk cohort (RR 0.77, 95% CI 0.67 to 0.87, and RR 0.36, 95% CI 0.28 to 0.45, respectively). The combination also reduced MI in the high CV risk cohort (RR 0.39, 95% CI 0.31 to 0.49). Benefits were similar when steroid users were included. CONCLUSIONS: These agents may have dual cardiopulmonary protective properties, thereby substantially altering prognosis of patients with COPD. These findings need confirmation in randomized clinical trials.

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PubMed2006

Challenges and opportunities for pharmacoepidemiology in drug-therapy decision making.

Pharmacoepidemiology is a relatively new and evolving science that attempts to quantify mainly adverse drug events and patterns of drug use in a large population. The strength of pharmacoepidemiology over randomized trials is the ability to quantify rare adverse events that may occur over long periods. Recently, discordance in the results of pharmacoepidemiologic studies has made it difficult for clinicians and policy makers to make informed drug-therapy decisions. This commentary addresses the strength of pharmacoepidemiology and the advances in the methodology of pharmacoepidemiologic studies over the years. We also discuss the potential problem of discordant results and urge pharmacoepidemiologists to develop good practice guidelines for the conduct of pharmacoepidemiologic studies.

Adverse Drug Reaction Reporting Systems↗
PubMed2006

Do angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers decrease the risk of hospitalization secondary to community-acquired pneumonia? A nested case-control study.

STUDY OBJECTIVE: As studies have shown that angiotensin-converting enzyme (ACE) inhibitors may lower the risk of developing pneumonia by increasing the cough reflex, we sought to explore the potential association between use of ACE inhibitors and the risk of hospitalization secondary to community-acquired pneumonia (CAP). To test this hypothesis further, we also looked at the risk for CAP in those taking angiotensin II receptor blockers (ARBs), as these drugs have a similar mechanism of action to that of ACE inhibitors but have minimal or no effect on the cough reflex. In addition, the putative protection against pneumonia may instead be related to general inhibition of the renin-angiotensin system. DESIGN: Nested case-control study. DATA SOURCE: Universal Quebec, Canada, administrative health databases. PATIENTS: From a cohort of 47,148 patients with coronary artery disease who had a revascularization procedure between 1996 and 2000, 1666 patients with CAP and 33,315 time-matched control subjects (20 controls for each case) were identified. MEASUREMENTS AND MAIN RESULTS: Conditional logistic regression analysis was used to estimate rate ratios, while controlling for potential confounders. No association was observed between patients receiving ACE inhibitors and hospitalization for CAP (rate ratio [RR] 0.98, 95% confidence interval [CI] 0.69-1.40). A similar lack of association was noted for those receiving ARBs (RR 1.02, 95% CI 0.70-1.49). CONCLUSION: In this case-control study, no association was found between use of ACE inhibitors or ARBs and risk of hospitalization secondary to CAP. Future studies are necessary to explore this association further.

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PubMed2005

Personal use of hair dyes and risk of cancer: a meta-analysis.

CONTEXT: Use of hair dyes has been suggested recently as a risk factor for several types of cancer in epidemiologic studies. This alarming news and controversial declarations by scientific organizations and general media have made necessary a systematic evaluation of the epidemiologic evidence. OBJECTIVE: To examine the association between personal use of hair dyes and relative risk of cancer. DATA SOURCES: We retrieved studies published in any language by systematically searching the MEDLINE (1966-January 2005), EMBASE, LILACS, and ISI Proceedings computerized databases and by manually examining the references of the original articles, reviews, and monographs retrieved. STUDY SELECTION: We included cohort and case-control studies reporting relative risk estimates and 95% confidence intervals (CIs) (or data to calculate them) of personal hair dye use and cancer. We excluded studies that dealt with occupational exposure. We carried out separate analyses for bladder, breast, and hematopoietic cancers and cancers of other sites. Seventy-nine studies were included of 210 articles identified in the search. DATA EXTRACTION: Data were extracted independently by 2 investigators. We used a standardized questionnaire to record information on study design, sample size, type of controls, year of publication, adjustment factors, and relative risks of cancer among ever users of hair dyes. When possible, we extracted association measures on use of permanent dyes and extensive use (>200 lifetime episodes of dye use). DATA SYNTHESIS: Study-specific relative risks were weighted by the inverse of their variance to obtain fixed- and random-effects pooled estimates. The pooled relative risk for ever users of hair dyes was 1.06 (95% CI, 0.95-1.18) for breast cancer (14 studies), 1.01 (95% CI, 0.89-1.14) for bladder cancer (10 studies), and 1.15 (95% CI, 1.05-1.27) for hematopoietic cancers (40 studies). Other cancers were examined by only 1 or 2 studies, of which the pooled or single relative risk was elevated for brain cancer, ovarian cancer, and cancer of the salivary glands. No effect was observed for use of permanent dyes or for extensive use. CONCLUSIONS: We did not find strong evidence of a marked increase in the risk of cancer among personal hair dye users. Some aspects related to hematopoietic cancer and other cancers that have shown evidence of increased risk in 1 or 2 studies should be investigated further.

Breast Neoplasms↗
PubMed2005

Intake of selenium in the prevention of prostate cancer: a systematic review and meta-analysis.

BACKGROUND: Recent studies have suggested that selenium intake may prevent the risk of developing prostate cancer. Results from some of these studies have given conflicting results. Because of these discrepant results we sought to explore the association between selenium intake and prostate cancer by conducting a systematic review and meta-analysis of the literature. METHODS: We systematically searched MEDLINE, EMBASE and Cochrane Library between 1966 and May 2005 for articles that examined the association between intake of selenium and the risk of prostate cancer. We abstracted the data from relevant studies. A random effects model was used to estimate pooled relative risks for both cohort and case-control studies. Heterogeneity was assessed graphically using a Funnel Plot. RESULTS: Sixteen studies (eleven cohort studies and five case-control studies) were included in the final analysis. The pooled relative risk of prostate cancer for any intake of selenium was 0.72 (0.61-0.84) for cohort studies and 0.74 (0.61-1.39) for case-control studies. The pooled relative risk of moderate intake was 0.74 (0.61-0.90) for cohort studies and 0.74 (0.39-1.39) for case-control studies. A dose-response trend was observed when we stratified the studies by disease severity. CONCLUSION: The results of our systematic review suggest that selenium intake may reduce the risk of prostate cancer. The results confirm the need for large randomized controlled trials, which are ongoing, to answer this question.

Canada↗
PubMed2005

Intake of vitamin E, vitamin C, and carotenoids and the risk of Parkinson's disease: a meta-analysis.

We studied the effect of vitamin C, vitamin E, and beta carotene intake on the risk of Parkinson's disease (PD). We did a systematic review and meta-analysis of observational studies published between 1966 and March 2005 searching MEDLINE, EMBASE, and the Cochrane Library. Eight studies were identified (six case-control, one cohort, and one cross-sectional). We found that dietary intake of vitamin E protects against PD. This protective influence was seen with both moderate intake (relative risk 0.81, 95% CI 0.67-0.98) and high intake (0.78, 0.57-1.06) of vitamin E, although the possible benefit associated with high intake of vitamin E was not significant. The studies did not suggest any protective effects associated with vitamin C or beta carotene. We conclude that dietary vitamin E may have a neuroprotective effect attenuating the risk of PD. These results require confirmation in randomised controlled trials.

Ascorbic Acid↗
PubMed2005

Knowledge, attitude and practice towards droplet and airborne isolation precautions among dental health care professionals in Shiraz, Iran.

OBJECTIVE: To determine the level of knowledge, attitude and practice among Iranian dental health care professionals towards droplet and airborne isolation precautions, in Shiraz, Iran. METHODS: A survey was developed and distributed to 152 Iranian dental professionals (faculty and students) from Shiraz University School of Medical Sciences, School of Dentistry, Shiraz, Iran. The self-administered questionnaire was composed of three parts (knowledge, attitude, and practice). After validation of the survey using the Kuder Richardson reliability test and Cronbach's alpha internal consistency coefficient, data was collected and analyzed using Analysis of Variance and the Duncan test to detect the differences among groups. The Spearman coefficient was used to determine the correlation between knowledge, attitude, and practice. RESULTS: The survey was completed by 152 (51.5%) of 295 potential respondents. Mean scores of knowledge, attitude, and practice towards droplets and airborne isolation precautions were poor (98 +/- 3.45, 10.51 +/- 6.26, 2.68 +/- 3.16 from the maximum scores of 11, 55, and 11, respectively). In addition, a positive linear correlation was found between two items of the survey including knowledge-attitude (rho = 0.438, p < 0.001), knowledge and practice (rho = 0.380, p < 0.001). CONCLUSION: Iranian dental professionals seemed to have low levels of knowledge, attitude and practice towards infection control.

Aerosols↗
PubMed2004

Risk of ischaemic stroke in people with migraine: systematic review and meta-analysis of observational studies.

OBJECTIVE: To explore the association between migraine and risk of ischaemic stroke. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Observational studies published between 1966 and June 2004 (identified through Medline and Embase) that examined the association between migraine and risk of ischaemic stroke. RESULTS: 14 studies (11 case-control studies and 3 cohort studies) were identified. These studies suggest that the risk of stroke is increased in people with migraine (relative risk 2.16, 95% confidence interval 1.89 to 2.48). This increase in risk was consistent in people who had migraine with aura (relative risk 2.27, 1.61 to 3.19) and migraine without aura (relative risk 1.83, 1.06 to 3.15), as well as in those taking oral contraceptives (relative risk 8.72, 5.05 to 15.05). CONCLUSIONS: Data from observational studies suggest that migraine may be a risk factor in developing stroke. More studies are needed to explore the mechanism of this potential association. In addition, the risk of migraine among users of oral contraceptives must be further investigated.

Adolescent↗
PubMed2004

Pharmacoepidemiology I: a review of pharmacoepidemiologic study designs.

This article is the first of two parts on pharmacoepidemiology, a relatively new science that explores drug efficacy or toxicity using large observational study designs. The number of pharmacoepidemiologic studies published in medical journals has increased, as these studies have explored drug-related questions that at times cannot be answered in randomized clinical trials. Four pharmacoepidemiologic study designs will be discussed that explore the association between a specific pharmacologic agent and a disease of interest: cohort studies, case-control studies, case-crossover studies, and case-time-control studies.

Case-Control Studies↗
PubMed2004

Pharmacoepidemiology II: the nested case-control study--a novel approach in pharmacoepidemiologic research.

This article on pharmacoepidemiology, the second of two parts, is a more focused discussion of the methodology of cohort studies and case-control studies, the basic methodologies of which were discussed in part I. The nested case-control study incorporates the strengths of both the cohort and case-control studies but may alleviate some of the methodologic challenges inherent in both types of studies. In a nested case-control study, a cohort of individuals is followed during certain time periods until a certain outcome is reached. The analysis is conducted as a case-control study in which cases are matched to only a sample of control subjects. Matching allows for control of potential confounding variables such as age, calendar time, and disease duration. Also, the time dependency of an exposure can be quantified without complicated statistical techniques. Matching the cases and controls by time allows the investigator to stratify exposure based on current, past, or intermittent use. By using the principles of epidemiology, the nested case-control study allows for the control of confounding variables, as well as better quantification of time-dependent exposures.

Case-Control Studies↗
PubMed2004

Macrolide therapy for Chlamydia pneumoniae in the secondary prevention of coronary artery disease: a meta-analysis of randomized controlled trials.

STUDY OBJECTIVE: As recent studies have shown that antibiotic therapy to eradicate Chlamydia pneumoniae may be beneficial in the secondary prevention of coronary artery disease, and studies to date may have lacked statistical power, we conducted a meta-analysis of randomized controlled trials to determine the role of antibiotic therapy in this patient population. DESIGN: Systematic review and meta-analysis of randomized controlled trials. PATIENTS: A total of 12,032 patients from nine studies. MEASUREMENTS AND MAIN RESULTS: We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register, and abstracts of conference proceedings to identify pertinent studies. The random effects model was used to estimate a pooled relative risk. Heterogeneity was assessed using the bootstrap version of the Q statistic with 1000 replications. In total, we reviewed nine randomized controlled trials enrolling 12,032 patients; six enrolled patients with acute coronary syndrome, two enrolled patients with stable coronary artery disease, and one enrolled a mixed population. Compared with placebo, macrolide therapy was not associated with a significant reduction in any coronary event (relative risk [RR] 0.98, 95% confidence interval [CI] 0.88-1.08), myocardial infarction or angina (RR 0.89, 95% CI 0.68-1.16), or overall mortality (RR 0.95, 95% CI 0.81-1.12). CONCLUSION: Our results do not support routine use of antichlamydial therapy for secondary prevention of coronary events.

Antibiotic Prophylaxis↗
PubMed2004

Quantifying adverse drug events : are systematic reviews the answer?

Quantifying adverse drug events (ADEs) is critical to clinicians, consumers and policy makers. Most ADE information comes from large clinical trials. Systematic reviews have become a popular tool in quantifying the efficacy of different therapeutic interventions and ADE data collected in randomised trials may be helpful in quantifying the risk associated with a specific pharmacological agent. However, clinicians who are interested in conducting systematic reviews of ADEs may face many challenges. These challenges are geared towards two main areas: poor quality of ADE reporting in randomised trials and poor indexing of ADEs in medical databases. In this review, we will discuss these challenges in detail using some examples from the literature. Where possible, we also discuss strategies that may overcome these problems. More rigourous standards of reporting ADEs in randomised trials, as well as better indexing of ADE terminology in medical databases, could one day make systematic reviews of ADEs a powerful tool for practising clinicians.

Adverse Drug Reaction Reporting Systems↗
PubMed2004

The role of tomato products and lycopene in the prevention of prostate cancer: a meta-analysis of observational studies.

PURPOSE: To determine whether intake of tomato products reduces the risk of prostate cancer using a meta-analysis. METHODS: We systematically searched MEDLINE and EMBASE and contacted authors to identify potential studies. Log relative risks (RRs) were weighed by the inverse of their variances to obtain a pooled estimate with its 95% confidence interval (CI). Logistic regression and Poisson regression analyses were used to determine the effect produced by a daily intake of one serving of tomato product. RESULTS: Eleven case-control studies and 10 cohort studies or nested case-control studies presented data on the use of tomato, tomato products, or lycopene and met our inclusion criteria. Compared with nonfrequent users of tomato products (1st quartile of intake), the RR of prostate cancer among consumers of high amounts of raw tomato (5th quintile of intake) was 0.89 (95% CI 0.80-1.00). For high intake of cooked tomato products, this RR was 0.81 (95% CI 0.71-0.92). The RR of prostate cancer related to an intake of one serving/day of raw tomato (200 g) was 0.97 (95% CI 0.85-1.10) for the case-control studies and 0.78 (95% CI 0.66-0.92) for cohort studies. CONCLUSIONS: Our results show that tomato products may play a role in the prevention of prostate cancer. However, this effect is modest and restricted to high amounts of tomato intake. Further research is needed to determine the type and quantity of tomato products with respect to their role in preventing prostate cancer.

Carotenoids↗
PubMed2003

Effect of non-steroidal anti-inflammatory drugs on risk of Alzheimer's disease: systematic review and meta-analysis of observational studies.

OBJECTIVES: To quantify the risk of Alzheimer's disease in users of all non-steroidal anti-inflammatory drugs (NSAIDs) and users of aspirin and to determine any influence of duration of use. DESIGN: Systematic review and meta-analysis of observational studies published between 1966 and October 2002 that examined the role of NSAID use in preventing Alzheimer's disease. Studies identified through Medline, Embase, International Pharmaceutical Abstracts, and the Cochrane Library. RESULTS: Nine studies looked at all NSAIDs in adults aged > 55 years. Six were cohort studies (total of 13 211 participants), and three were case-control studies (1443 participants). The pooled relative risk of Alzheimer's disease among users of NSAIDs was 0.72 (95% confidence interval 0.56 to 0.94). The risk was 0.95 (0.70 to 1.29) among short term users (< 1 month) and 0.83 (0.65 to 1.06) and 0.27 (0.13 to 0.58) among intermediate term (mostly < 24 months) and long term (mostly > 24 months) users, respectively. The pooled relative risk in the eight studies of aspirin users was 0.87 (0.70 to 1.07). CONCLUSIONS: NSAIDs offer some protection against the development of Alzheimer's disease. The appropriate dosage and duration of drug use and the ratios of risk to benefit are still unclear.

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