Acute myocardial infarction and prior antibiotic use

Increased risk of infectious disease requiring hospitalization among patients with psoriasis: a population-based cohort

BACKGROUND

Immunologic alterations caused by psoriasis and/or its therapies may affect the risk of serious infections.

OBJECTIVE

For patients with psoriasis, we explored the overall and therapy-related risk of contracting an infectious disease (ID) requiring hospitalization in a large population-based cohort.

METHODS

The incidence of ID was compared between patients with psoriasis and a randomly selected cohort (ratio 1:5) using hospital and pharmacy databases covering 2.5 million Dutch residents between 1997 and 2008. First and multiple IDs were defined and categorized into 20 groups based on primary International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnoses. Multivariate Cox regression and Poisson event-count models were used to test the risk difference of IDs between patients with psoriasis and reference cohort.

RESULTS

A total of 25,742 patients with psoriasis and 128,710 reference subjects were followed up for approximately 6 years. The likelihood of IDs in patients with psoriasis was twice as high as the reference population (908 vs 438 events/100,000 person-years, crude hazard ratio 2.08, 95% confidence interval 1.96-2.22). In a multivariate model the hazard ratio decreased to 1.54 (95% confidence interval 1.44-1.65). This risk was highest for patients with more severe psoriasis (adjusted hazard ratio 1.81, 95% confidence interval 1.57-2.08), but was not associated with recent systemic antipsoriatic drug dispensing. Respiratory tract, abdominal, and skin infections occurred most frequently in patients with psoriasis. Multiple event analysis that counted the total number of infectious discharge diagnoses gave similar results.

LIMITATIONS

No data were available on lifestyle factors.

CONCLUSION

The risk of severe infections was significantly higher for patients with psoriasis compared with control subjects and could not be explained by exposure to systemic antipsoriatic drugs.

Psoriasis may not be an independent risk factor for acute ischemic heart disease hospitalizations: results of a large population-based Dutch cohort

Although psoriasis has been associated with components of the metabolic syndrome, its association with myocardial infarction is less clear. A cohort study was conducted using hospital and pharmacy records of 2.5 million Dutch residents between 1997 and 2008. The risk of ischemic heart disease (IHD) hospitalizations was compared between psoriasis patients and a matched reference cohort. Additional adjustments were made for healthcare consumption and use of cardiovascular drugs. A total of 15,820 psoriasis patients and 27,577 reference subjects were included, showing an incidence rate of 611 and 559 IHD per 100,000 person-years, respectively (P=0.066). The age- and gender-adjusted risk of IHD was comparable between both cohorts (hazard ratio (HR)=1.10, 95% confidence interval 0.99-1.23). Before cohort entry, psoriasis patients used more antihypertensive, antidiabetic, and lipid-lowering drugs and were more often hospitalized. Adjusting for these confounders decreased the HR for IHD, but it remained comparable between both populations. There was no different risk of IHD between the subgroup of patients who only used topicals versus those who received systemic therapies or inpatient care for their psoriasis. This study, therefore, suggests that psoriasis is not a clinically relevant risk factor for IHD hospitalizations on the population level.

Antibiotics active against Chlamydia do not reduce the risk of myocardial infarction

OBJECTIVE

There is evidence that Chlamydia pneumoniae (CP) is involved in the aetiology of myocardial infarction (MI). Randomised trials do not support a beneficial effect of antibiotics in secondary prevention of MI, but the evidence for an effect on primary prevention is conflicting. We investigated if past use of antibiotics active against CP is associated with a decreased risk of developing MI.

METHODS

We conducted a population-based case-control study of 4166 patients hospitalised due to MI from 1 January 1994 to 1 September 1999 in the County of Funen, Denmark. Controls (n=16,664) were a random sample of inhabitants, matched for age and sex. Confounders controlled for in the analysis were gender, age, obstructive pulmonary disease, diabetes, previous MI and known atherosclerotic antecedents. Previous use of antibiotics active against CP (macrolides, tetracyclines and quinolones) and of antibiotics not active against CP (penicillins) was analysed among the cases and controls.

RESULTS

The risk of MI was not associated with previous exposure to macrolides (OR: 1.0; CI: 0.9-1.1), tetracyclines (OR: 1.0; CI: 0.9-1.2) or quinolones (OR: 1.0; CI: 0.9-1.2) or combinations of the three drugs (OR: 1.0; CI: 0.9-1.1). There was no sign of a protective effect in subgroups defined by high cumulative doses of antibiotics, various time-windows of exposure, risk factors of MI or other co-morbidity. OR was 1.1 (0.9-1.3) in persons with no atherosclerotic antecedents.

CONCLUSION

The study does not support the hypothesis of a decreased risk of MI in patients exposed to antibiotics active against CP.

Chronic infection and coronary artery disease

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these relationships are still just associations. Failure to confirm initial reports of serologic associations also has been common. Specific causative relationships on par with that determined between H pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C pneumoniae, the effect may result from direct vessel wall colonization that may damage the vessel either directly or indirectly by initiating immunologic responses. In other cases the effect may simply be that of enhancing the pre-existing chronic inflammatory response of the body to standard risk factors such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence pre-existing plaque by enhancing T-cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Hence chronic infection may play a role either in the initiation, progression, or the destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support an etiologic role in atherosclerosis include C pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents including other herpes viruses, influenza, other specific bacteria (such as M pneumoniae), and chronic infections with common bacterial agents (periodontal disease, chronic bronchitis, and chronic urinary tract infection, among others) [191]. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate further the potential of a variety of treatment approaches, including antibiotics.

Quinolones:

Quinolones block the rapid component of the delayed rectifier potassium current (Ik) in a dose dependent manner. This electrophysiological action translates into prolongation of the QT interval and may predispose to development of torsades de pointes. QT prolongation appears to be a class effect but there is a wide range of potency among class members. According to the available evidence, the fluoroquinolones that are currently on the market present a low risk of drug induced torsades de pointes, with a frequency of this adverse event occurring at a rate of approximately 0.2-2.7 per million prescriptions. The safest member of the class appears to be ciprofloxacin. ECG monitoring during initiation of quinolone treatment is indicated only in patients with conditions known to predispose to torsades or to those receiving concomitant medications that prolong the QT interval.

Antibiotic treatment of atherosclerosis

PURPOSE OF REVIEW

Several lines of evidence have demonstrated an association between a variety of chronic bacterial infections and atherosclerotic cardiovascular disease. This has led to the proposal that antibiotic therapy might be helpful in the secondary prevention of atherosclerosis. A variety of smaller pilot studies have been reported testing this hypothesis and several large multicenter trials are also underway. The purpose of this review is to summarize the results of these studies and comment on their implications for the treatment of atherosclerosis.

RECENT FINDINGS

Most of the antibiotic studies to date have been secondary prevention studies that have targeted patients exposed to Chlamydia pneumoniae. Most have used either azithromycin or roxithromycin with treatment courses ranging from a few days to 3 months. Several small studies of coronary artery disease patients have shown significant promise for reducing cardiovascular events such as death, myocardial infarction, or admission for unstable angina. However, other studies have not been so positive. Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders, WIZARD, the largest study to date, in which stable post-myocardial infarction patients were randomized to receive a 3-month course of azithromycin or placebo, demonstrated a significant reduction in death and myocardial infarction by 6 months, but this benefit was not sustained throughout the remaining course of follow-up. The Azithromycin and Coronary Events (ACES) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE-IT) trials are ongoing and are testing the effect of more prolonged treatment duration.

SUMMARY

A variety of antibiotic trials for the secondary prevention of atherosclerosis have been performed. Several pilot studies have shown significant positive clinical effects, but, thus far, no large randomized trial has confirmed those findings. Some concerns over the antibiotics chosen and the duration of treatment have been raised. Other trials are underway to address some of those concerns. In the meantime, no recommendation for the use of antibiotic therapy for the secondary prevention of atherosclerosis can yet be made.

Antibiotics in primary prevention of stroke in the elderly

BACKGROUND AND PURPOSE

An increasing number of reports have linked infections to atherosclerosis and thrombosis. Thus, use of antibiotics may lower the risk of developing cerebrovascular disease. We investigated whether antibiotic use is associated with the risk of stroke in elderly individuals treated for hypertension.

METHODS

A cohort of 29 937 elderly subjects initiating antihypertensive therapy between 1982 and 1995 was formed from the Quebec healthcare insurance database. A nested case-control design was used in which each subject hospitalized with a primary discharge diagnosis of stroke between 1987 and 1995 was matched on calendar time to 5 randomly selected controls from the cohort. Conditional logistic regression was used to estimate odds ratios of stroke after adjustment for predisposing factors.

RESULTS

We identified 1888 cases and 9440 controls. The overall adjusted odds ratio for current antibiotic use was 0.80 (95% confidence interval, 0.63 to 1.01), and that for recent use was 0.81 (95% confidence interval, 0.70 to 0.94). Penicillin was the only individual antibiotic class that showed a protective association across different time windows. No significant association was found between stroke risk and the use of fluoroquinolones, macrolides, tetracyclines, or cephalosporins.

CONCLUSIONS

Although no clear, consistent associations between overall antibiotic use and cerebrovascular disease could be found, an intriguing association between penicillin use and stroke should be explored further.

Role of antibiotics for the prevention of cardiovascular disease

OBJECTIVE

To evaluate the data regarding the use of antibiotic therapy for the prevention of cardiovascular events.

DATA SOURCES

Pertinent literature was identified through a MEDLINE search (1966-September 2001) and through other secondary literature databases and/or bibliographies of pertinent articles.

DATA SYNTHESIS

Cardiovascular disease is a common cause of morbidity and mortality among the general population, with well-defined risk factors (e.g., diabetes, hypertension, hyperlipidemia, cigarette smoking, genetic predisposition). Clinical data evaluating the association between the aforementioned risk factors and the development of atherosclerosis and subsequent cardiovascular disease are substantial; however, these risk factors may only partially explain the high prevalence of cardiovascular disease. The presence of Chlamydia pneumoniae within atherosclerotic lesions has been documented and may be an additional risk factor for the development and progression of cardiovascular disease.

CONCLUSIONS

The results of primary and secondary prevention trials have shown conflicting evidence with regard to the beneficial effects of antibiotic therapy to reduce cardiovascular events. Currently, the lack of certainty in published data does not support the use of antibiotics for the prevention of cardiovascular disease. Clinicians should continue to emphasize interventions proven to reduce adverse cardiovascular events such as smoking cessation, reduction of hyperlipidemia, and control of hypertension.

Secondary prevention of coronary artery disease with antimicrobials: current status and future directions

Over the past several decades, coronary artery disease (CAD) has become the major health problem in the Western world with more than 50% of deaths attributed to its complications. The exact causes of atherosclerosis are not clearly known, although multiple risk factors (e.g. hypertension, hyperlipidemia, diabetes mellitus, family history, and smoking) have been well described. However, these risk factors account for only about 50% of the total risk of CAD. Consequently, an ongoing search is under way to discover new risk factors for atherosclerosis as well as the basic underlying causes of progression. Although the evidence is not yet definitive, recent studies have shown that chronic infection by such bacterial organisms as Chlamydia pneumoniae, Helicobacter pylori, and a variety of dental pathogens may play a causative role in atherosclerosis. If this is true, then antimicrobial therapy may be helpful in the secondary prevention of CAD. Indeed, several small studies have already been completed testing this hypothesis. This article reviews the evidence associating these bacterial pathogens to CAD and presently available information regarding the use of antibiotics in the setting. At present, most studies evaluating the potential efficacy antimicrobials in the secondary prevention of CAD have tested the use of macrolide antibodies. Although several small preliminary studies have reported promising results favoring a clinical benefit from even short (<3 months) courses of antimicrobial therapy, the first large clinical trial, the Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders (WIZARD) study, did not show a statistically significant beneficial effect of a 3 month course of azithromycin over placebo by the end of up to 4 years follow-up. However, a statistically significant (p = 0.03) 33% reduction in death and myocardial infarction was found at 6 months, 3 months after the discontinuation of antibiotics. This robust clinical benefit, however, was not sustained over the ensuing 3.5 years of follow-up. These disappointing long-term outcomes of short-term therapy with antimicrobials may be explained by the recently discovered difficulty found in eradicating chronic vascular infections such as C. pneumoniae. It remains possible that longer term antimicrobial therapy or short-term use of more potent single agents or combinations, capable of effectively eradicating the offending organisms might provide added clinical benefit in the fight against CAD. Further studies are ongoing or planned to evaluate this potential. In the meantime, it is not presently recommended that antimicrobials be routinely prescribed for the secondary prevention of CAD.