Variants in ZFHX3 are associated with atrial fibrillation in individuals of European ancestry

We conducted meta-analyses of genome-wide association studies (GWAS) for atrial fibrillation (AF) in participants from five community-based cohorts. Meta-analyses of 896 prevalent (15,768 referents) and 2,517 incident (21,337 referents) AF cases identified a novel locus for AF (ZFHX3, rs2106261, risk ratio [RR]=1.19; P=2.3×10⁻⁷), an association that was replicated in the German AF Network (odds ratio=1.44; P=1.6×10⁻¹¹). Combining the discovery and replication results, rs2106261 was significantly associated with AF (RR=1.25; P=1.8×10⁻¹⁵).

A genome-wide association study of acenocoumarol maintenance dosage

Several genome-wide association studies have been performed on warfarin. For acenocoumarol, the most frequently used coumarin in many countries worldwide, pharmacodynamic influences are expected to be comparable. Pharmacokinetics however might differ. We aimed to confirm known or identify new genetic variants contributing to interindividual variation on stabilized acenocoumarol dosage by a GWAS. The index population consisted of 1451 Caucasian subjects from the Rotterdam study and results were replicated in 287 subjects from the Rotterdam study extended cohort. Both cohorts were genotyped on the Illumina 550K Human Map SNP array. From polymorphisms tested for association with acenocoumarol dosage, 35 single nucleotide polymorphisms (SNPs) on chromosome 16 and 18 SNPs on chromosome 10 reached genome-wide significance. The SNP with the lowest P-value was rs10871454 on chromosome 16 linked to SNPs within the vitamin K epoxide reductase complex subunit 1 (VKORC1) (P = 2.0 x 10(-123)). The lowest P-value on chromosome 10 was obtained by rs4086116 within cytochrome P450 2C9 (CYP2C9) (P = 3.3 x 10(-24)). After adjustment for these SNPs, the rs2108622 polymorphism within cytochrome P450 4F2 (CYP4F2) gene on chromosome 19 reached genome-wide significance (P = 2.0 x 10(-8)). On chromosome 10, we further identified genetic variation in the cytochrome P450 2C18 (CYP2C18) gene contributing to variance of acenocoumarol dosage. Thus we confirmed earlier findings that acenocoumarol dosage mainly depends on polymorphisms in the VKORC1 and CYP2C9 genes. Besides age, gender, body mass index and target INR, one polymorphism within each of the VKORC1, CYP2C9, CYP4F2 and CYP2C18 genes could explain 48.8% of acenocoumarol dosage variation.

BclI glucocorticoid receptor polymorphism and smoking in the general population

We studied the hypothesis that the BclI polymorphism of the glucocorticoid receptor gene is associated with an increased probability of being a (heavy) smoker and a decreased ability to quit smoking. The study cohort consisted of all subjects in the Rotterdam Study, a Dutch population-based cohort of people aged 55 years and older, for whom BclI genotyping and smoking status at baseline were available. In prospective analyses, the smoking status was reassessed during three additional examination rounds. Logistic regression analysis was used to study the association between BclI polymorphism and being a smoker or a heavy smoker at baseline. Furthermore, the relationship between BclI polymorphism and incident smoking cessation was tested with Cox proportional hazards analysis within those who smoked at baseline. In total, 6358 subjects were included in the study. The presence of a G-allele was not associated with current smoking at baseline [odds ratio (OR) = 0.96, 95%confidence interval (CI): 0.85-1.09] or with the incidence of smoking cessation during follow-up [hazard ratio (HR) = 0.98, 95%CI: 0.80-1.19]. Within current smokers, having a G-allele was not significantly associated with the risk of being a heavy smoker when measured by pack-years smoked (OR = 1.07, 95%CI: 0.85-1.35) or daily consumption of tobacco (OR = 1.10, 95%CI: 0.88-1.37). We were not able to replicate the earlier findings indicating that the proportion of current smokers is lower among carriers of the CC-genotype of the BclI glucocorticoid receptor. Furthermore, the BclI glucocorticoid receptor polymorphism did not predict the incidence of smoking cessation in the general elderly population.

Genetic variation in the organic cation transporter 1 is associated with metformin response in patients with diabetes mellitus

The organic cation transporter 1, encoded by the SLC22A1 gene, is responsible for the uptake of the anti-hyperglycaemic drug, metformin, in the hepatocyte. We assessed whether a genetic variation in the SLC22A1 gene is associated with the glucose-lowering effect of metformin. Incident metformin users in the Rotterdam Study, whose HbA1c measurements were available, were identified. Associations between 11 tagging single nucleotide polymorphisms in the SLC22A1 gene and change in the HbA1c level were analyzed. A total of 102 incident metformin users were included in this study sample. Except for the rs622342 A>C polymorphism, no significant differences in metformin response were observed. For each minor C allele at rs622342, the reduction in HbA1c levels was 0.28% less (95% CI 0.09-0.47, P=0.005). After Bonferroni correction, the P-value was 0.050. To conclude, genetic variation at rs622342 in the SLC22A1 gene was associated with the glucose-lowering effect of metformin in patients with diabetes mellitus.

Common variants at ten loci influence QT interval duration in the QTGEN Study

QT interval duration, reflecting myocardial repolarization on the electrocardiogram, is a heritable risk factor for sudden cardiac death and drug-induced arrhythmias. We conducted a meta-analysis of three genome-wide association studies in 13,685 individuals of European ancestry from the Framingham Heart Study, the Rotterdam Study and the Cardiovascular Health Study, as part of the QTGEN consortium. We observed associations at P < 5 x 10(-8) with variants in NOS1AP, KCNQ1, KCNE1, KCNH2 and SCN5A, known to be involved in myocardial repolarization and mendelian long-QT syndromes. Associations were found at five newly identified loci, including 16q21 near NDRG4 and GINS3, 6q22 near PLN, 1p36 near RNF207, 16p13 near LITAF and 17q12 near LIG3 and RFFL. Collectively, the 14 independent variants at these 10 loci explain 5.4-6.5% of the variation in QT interval. These results, together with an accompanying paper, offer insights into myocardial repolarization and suggest candidate genes that could predispose to sudden cardiac death and drug-induced arrhythmias.

Genetic variation in the multidrug and toxin extrusion 1 transporter protein influences the glucose-lowering effect of metformin in patients with diabetes: a preliminary study

OBJECTIVE

Metformin, an oral glucose-lowering drug, is taken up in hepatocytes by the organic cation transporter (OCT) 1 and in renal epithelium by OCT2. In these cells, the multidrug and toxin extrusion (MATE) 1 protein, encoded by the SLC47A1 gene, is responsible for the excretion of metformin into the bile and urine, respectively. We studied the effect of single nucleotide polymorphisms (SNPs) in the SLC47A1 gene on the A1C-lowering effect of metformin.

RESEARCH DESIGN AND METHODS

We identified all incident metformin users in the Rotterdam Study, a population-based cohort study. Associations between 12 tagging SNPs in the SLC47A1 gene and change in A1C level were analyzed.

RESULTS

One hundred and sixteen incident metformin users were included in the study sample. The rs2289669 G>A SNP was significantly associated with metformin response. For the other SNPs, no associations were found. For each minor A allele at rs2289669, the A1C reduction was 0.30% (95% CI -0.51 to -0.10; P = 0.005) larger. After Bonferroni correction for multiple testing, the P value was 0.045.

CONCLUSIONS

The rs2289669 G>A SNP is associated with a reduction in A1C level, consistent with a reduction in MATE1 transporter activity. These results suggest that the transporter MATE1, encoded by SLC47A1, may have an important role in the pharmacokinetics of metformin, although replication is necessary.

Duration of antihypertensive drug use and risk of dementia: A prospective cohort study

BACKGROUND

The evidence from prospective observational research for a protective effect of antihypertensive drug use on the risk of dementia is far from uniform. Duration of follow-up was limited and relied mainly on baseline drug exposure data without information on duration of use. We investigated the association between the duration of antihypertensive use and risk of dementia.

METHODS

We followed 6,249 participants (mean 68.4 years, 60% women) of a prospective, population-based cohort from baseline (1990-1993) until 2005 for incident dementia. Continuous data on filled prescriptions came from pharmacy records. Total cumulative duration of antihypertensive use was expressed in years. We subtracted a latent 4-year period before the date of dementia diagnosis in the quantification of exposure duration to avoid potential bias in antihypertensive prescription due to prodromal changes in blood pressure or cognition. With Cox regression models, we calculated crude and adjusted hazard ratios (HRs) of all dementia and Alzheimer disease (AD) with antihypertensive use vs never used.

RESULTS

Compared to never used, antihypertensive use was associated with a reduced risk of all dementia (adjusted HR per year of use 0.95; 95% confidence interval [CI] 0.91-0.99). We observed an 8% (95% CI -15% to -1%) risk reduction per year of use for persons < or =75 years, whereas for persons >75 years this was 4% (95% CI -11% to 4%). Equivalent estimates were observed for AD. No apparent differences were observed among different types of antihypertensive drugs.

CONCLUSIONS

Antihypertensive drug use was associated with 8% risk reduction of dementia per year of use for persons < or =75 years.

Protective effect of a GRK5 polymorphism on heart failure and its interaction with beta-adrenergic receptor antagonists

EVALUATION OF: Liggett SB, Cresci S, Kelly RJ et al.: A GRK5 polymorphism that inhibits beta-adrenergic receptor signaling is protective in heart failure. Nat. Med. 14, 510-517 (2008). beta-Adrenoceptor blockade therapy was developed for the treatment of hypertension but is now also a cornerstone in the treatment of heart failure. Based on the mechanisms of action and current knowledge of pathway signaling, Ligget et al. hypothesized that genetic variants within G-protein coupled receptor kinases might alter disease course and response to beta-adrenoceptor blockade therapy. Following a multistep approach, a common variant in GRK5 was identified as being important in vitro and in vivo (mouse model) in beta-adrenergic desensitization, and was epidemiologically related to survival and therapy response in African-Americans. Although such a variety of research approaches is appealing, owing to the large number of used methods readers remain puzzled on some issues because it is not possible to give all details of each individual study. Therefore, interpretation of the overwhelming amount of results is difficult. In an era of shifting emphasis from classic hypothesis driven pharmacogenetics to genome-wide association studies, this study shows that hypothesis driven translational research is still of high value, especially in phenotypes as investigated here.

The CYP2D6*4 polymorphism affects breast cancer survival in tamoxifen users

Cytochrome P450 2D6 (CYP2D6) plays an important role in the formation of endoxifen, the active metabolite of tamoxifen. In this study the association between the most prevalent CYP2D6 null-allele in Caucasians (CYP2D6*4) and breast cancer mortality was examined among all incident users of tamoxifen in a population-based cohort study. Breast cancer mortality was significantly increased in patients with the * 4/*4 genotype (HR = 4.1, CI 95% 1.1-15.9, P = 0.041) compared to wild type patients. The breast cancer mortality increased with a hazard ratio of 2.0 (CI 95% 1.1-3.4, P = 0.015) with each additional variant allele. No increased risk of all-cause mortality or all-cancer mortality was found in tamoxifen users carrying a CYP2D6*4 allele. The risk of breast cancer mortality is increased in tamoxifen users with decreased CYP2D6 activity, consistent with the model in which endoxifen formation is dependent on CYP2D6 activity.

Pharmacogenetics of cardiovascular drug therapy

In developed countries cardiovascular disease is one of the leading causes of death. Cardiovascular drugs such as platelet aggregation inhibitors, oral anticoagulants, antihypertensives and cholesterol lowering drugs are abundantly prescribed to reduce risk of cardiovascular disease. Notable interindividual variation exists in the response to these pharmacotherapeutic interventions, which can be partially explained by factors such as gender, age, diet, concomitant drug use and environmental factors. Notwithstanding, a great part of this variability remains unknown. To a smaller or larger extent, genetic variability may contribute to the variability in response to these cardiovascular drugs. This review gives an overview of pharmacogenetic studies of genes that were reported to be associated with four commonly prescribed drugs/drug classes (platelet aggregation inhibitors, coumarins, antihypertensives and statins) and were studied at least 2 times with a similar outcome measure. In the field of cardiovascular drug therapy, polymorphisms in candidate genes such as the cycloxygenase-1, vitamin K reductase complex subunit 1, CYP2C9, alpha adducin and 3-hydroxy-3-methylglutaryl-CoA reductase have received a great amount of interest in the pharmacogenetics of aspirin, coumarins, antihypertensives and statins respectively. However, only variations in VKORC1 and CYP2C9 have consistently been associated with drug response (coumarins) and have clinical implications. Clinical trials should provide evidence for the effectiveness of genotyping before this procedure will be a part of every day anticoagulant therapy. In spite of the tremendous amount of publications in this field, there is no reason to advocate for genetic testing for any other drugs cardiovascular drug therapy yet. Current approaches in pharmacogenetic research do not seem to lead to results that meet our expectations of individualized medicine. Therefore, new approaches are needed addressing issues and challenges such as the number of SNPs studied, study power, study design and application of new statistical methods in (pharmaco-)genetic analysis.

The Rotterdam Study: 2010 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in close to a 1,000 research articles and reports (see www.epib.nl/rotterdamstudy). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Statins are associated with a reduced risk of Alzheimer disease regardless of lipophilicity. The Rotterdam Study

BACKGROUND

Cross-sectional reports suggest that statin users are less likely to have Alzheimer disease (AD). Prospective studies have provided inconsistent evidence. Moreover, it is unclear whether the association differs for lipophilic statins, those that could more easily pass the blood-brain barrier and hydrophilic statins.

OBJECTIVES

To prospectively evaluate whether use of statins is associated with the risk of AD, and to determine whether associations differ for lipophilic and hydrophilic statins.

METHOD

6992 participants of the prospective, population-based Rotterdam Study were followed, from baseline (1990-1993) until January 2005 for incident AD. Data on all filled prescriptions came from pharmacy records. For each date on which each event occurred, cholesterol-lowering drug use for the person who experienced the event and all remaining persons in the cohort was categorised as "any" or "never" use. A distinction was made between statin, lipophilic and hydrophilic statins, and non-statin cholesterol-lowering drugs. Data were analysed with the Cox regression analysis, adjusting for sex, age and potential confounders.

RESULTS

During follow-up (mean 9 years), 582 persons developed AD. Compared with never use of cholesterol-lowering drugs, statin use was associated with a decreased risk of AD (HR 0.57; 95% CI 0.37 to 0.90), but non-statin cholesterol-lowering drug use was not (HR 1.05; 95% CI 0.45 to 2.44). HRs were equal for lipophilic (HR 0.54; 95% CI 0.32 to 0.89) and hydrophilic statins (HR 0.54; 95% CI 0.26 to 1.11).

CONCLUSION

In the general population, the use of statins, but not of non-statin cholesterol-lowering drugs, was associated with a lower risk of AD compared with never use of cholesterol-lowering drugs. The protective effect was independent of the lipophilicity of statins.

Recruitment of participants through community pharmacies for a pharmacogenetic study of antihypertensive drug treatment

OBJECTIVE

To describe the design, recruitment and baseline characteristics of participants in a community pharmacy based pharmacogenetic study of antihypertensive drug treatment.

SETTING

Participants enrolled from the population-based Pharmaco-Morbidity Record Linkage System.

METHOD

We designed a nested case-control study in which we will assess whether specific genetic polymorphisms modify the effect of antihypertensive drugs on the risk of myocardial infarction. In this study, cases (myocardial infarction) and controls were recruited through community pharmacies that participate in PHARMO. The PHARMO database comprises drug dispensing histories of about 2,000,000 subjects from a representative sample of Dutch community pharmacies linked to the national registrations of hospital discharges.

RESULTS

In total we selected 31010 patients (2777 cases and 28233 controls) from the PHARMO database, of whom 15973 (1871 cases, 14102 controls) were approached through their community pharmacy. Overall response rate was 36.3% (n = 5791, 794 cases, 4997 controls), whereas 32.1% (n = 5126, 701 cases, 4425 controls) gave informed consent to genotype their DNA. As expected, several cardiovascular risk factors such as smoking, body mass index, hypercholesterolemia, and diabetes mellitus were more common in cases than in controls.

CONCLUSION

Furthermore, cases more often used beta-blockers and calcium-antagonists, whereas controls more often used thiazide diuretics, ACE-inhibitors, and angiotensin-II receptor blockers. We have demonstrated that it is feasible to select patients from a coded database for a pharmacogenetic study and to approach them through community pharmacies, achieving reasonable response rates and without violating privacy rules.

A common NOS1AP genetic polymorphism is associated with increased cardiovascular mortality in users of dihydropyridine calcium channel blockers

AIM

Recently, a polymorphism in the NOS1AP gene (rs10494366), a regulator of neuronal nitric oxide synthase (nNOS), was associated with QTc prolongation. Both nNOS and calcium channel blockers (CCBs) regulate intracellular calcium levels and have an important role in cardiovascular homeostasis. The aim was to investigate whether this polymorphism is associated with cardiovascular mortality in users of CCBs.

METHODS

The data from the Rotterdam study, a population-based closed cohort study of Caucasian individuals of > or =55 years of age, were used. We identified 1113 participants in the Rotterdam Study who were prescribed CCBs for the first time between 1991 and 2005. All-cause and cardiovascular mortality was assessed in participants who were prescribed CCBs with different NOS1AP rs10494366 genotypes using Cox proportional hazard models.

RESULTS

In participants starting on dihydropyridine CCBs (amlodipine, nifedipine and others) all-cause mortality (n = 79) risks were higher in participants with the TG [hazard ratio (HR) 2.57, 95% confidence interval (CI) 1.24, 5.34] or the GG genotype (HR 3.18, 95% CI 1.18, 8.58) than in participants with the referent TT genotype. Cardiovascular mortality (n = 54) risks were 3.51 (95% CI 1.41, 8.78) for the TG genotype and 6.00 (95% CI 1.80, 20.0) for the GG genotype. No differences in all-cause mortality or cardiovascular mortality were seen in participants starting with the nondihydropyridine CCBs verapamil or diltiazem.

CONCLUSION

The minor G allele of rs10494366 in the NOS1AP gene is associated with increased all-cause and cardiovascular mortality in Caucasian users of dihydropyridine CCBs. The mechanism underlying the observed association is unknown.

Inappropriate benzodiazepine use in older adults and the risk of fracture

AIMS

The Beers criteria for prescribing in elderly are well known and used for many drug utilization studies. We investigated the clinical value of the Beers criteria for benzodiazepine use, notably the association between inappropriate use and risk of fracture.

METHODS

We performed a nested case-control study within the Rotterdam Study, a population-based cohort study in 7983 elderly. The proportion of 'inappropriate' benzodiazepine use according to the Beers criteria was compared between fracture patients and controls. 'Inappropriate' use for elderly implies use of some long-acting benzodiazepines and some intermediate/short-acting ones exceeding a suggested maximum daily dose. Also, alternative criteria were applied to compare the risk of fracture. Cases were defined as persons with incident fracture between 1991 and 2002 who were current benzodiazepine users on the fracture date. Controls were matched on fracture date and were also current benzodiazepine users.

RESULTS

The risk of fracture in 'inappropriate' benzodiazepine users according to the Beers criteria was not significantly different from 'appropriate' users [odds ratio (OR) 1.07, 95% confidence interval (CI) 0.72, 1.60]. However, a significantly higher risk of fracture was found in 'high dose' users and a longer duration of use (14-90 days), irrespective of the type of benzodiazepine (OR 3.45, 95% CI 1.38, 8.59).

CONCLUSIONS

These findings suggest that inappropriate benzodiazepine use according to the Beers criteria is not associated with increased risk of fracture. Daily dose and longer duration of use (>14 days) is associated with higher risk of fracture, irrespective of the type of benzodiazepine prescribed.

High free thyroxine levels are associated with QTc prolongation in males

The literature on the effect of excess thyroid hormone on ventricular repolarization is controversial. To study whether free thyroxine (T(4)) and TSH are associated with QTc prolongation we conducted population-based cohort study. This study was conducted as part of the Rotterdam Study and included 365 men and 574 women aged 55 years and older with an electrocardiogram, who were randomly sampled for the assessment of thyroid status (free T(4)/TSH) at baseline, after exclusion of participants with hypothyroidism, use of antithyroid drugs, thyroid hormones or digoxin, left ventricular hypertrophy, and left and right bundle branch block. Endpoints were the length of the QTc interval and risk of borderline QTc prolongation. The associations were examined by means of linear and logistic regression analysis, adjusted for age and gender, diabetes mellitus, myocardial infarction, hypertension, and heart failure. Overall, there was no significant association between TSH and QTc interval (0.8 ms (95% confidence interval (CI) -3.5, 5.2) in the first quintile compared with the fifth quintile). Subjects in the fifth quintile of free T(4) did not have an increased QTc interval (3.2 ms (95% CI -1.1, 7.6)); stratification on gender showed an increment of 10.9 ms (95% CI 3.4, 18.3) in the fifth quintile in men and 1.1 ms (95% CI -4.2, 6.3) in the fifth quintile of free T(4) in women. When compared with subjects in the first quintile, male subjects in the fifth quintile of free T(4) had a significantly increased risk of a borderline QTc interval and QTc prolongation (odds ratio 2.40 (95% CI 1.20, 4.80)). High levels of free T(4) are associated with substantial QTc prolongation in men of up to 10 ms. The fact that free T(4) is also associated with a significantly increased risk of borderline and prolonged QTc values with its risk of sudden cardiac death, endorses the clinical importance of our findings.

Increasing exposure to drug-drug interactions between 1992 and 2005 in people aged > or = 55 years

BACKGROUND

Drug-drug interactions (DDIs) are responsible for a variety of adverse reactions, particularly in an elderly population.

OBJECTIVE

To assess the frequency and potential clinical relevance of DDIs in a population aged > or = 55 years.

METHODS

Exposure to DDIs was assessed in 7842 people participating in the Rotterdam Study, a population-based cohort study. These people were followed between 1 January 1992 and 1 July 2005. The DDI list of the Royal Dutch Association for the Advancement of Pharmacy, in which DDIs are categorized by potential clinical relevance and quality of evidence, was used. Simultaneous use of interacting drug combinations was calculated on the basis of drug dispensing data from community pharmacies.

RESULTS

The incidence of a first dispensing of DDIs in the study period was 10.5 per 100 person-years and 2.7 per 100 person-years for potentially life-threatening DDIs. The prevalence of DDIs in people aged > or = 70 years increased from 10.5% in 1992 to 19.2% in 2005. Ten DDIs comprised two-thirds of the total exposure time to DDIs. The prevalence of potentially life-threatening DDIs in people aged > or = 70 years increased from 1.5% to 2.9%. This increase was most likely caused by an increase in use of spironolactone combined with renin-angiotensin-aldosterone system inhibitors.

CONCLUSION

A large number of people in the Netherlands aged > or = 55 years are exposed to DDIs and this number has increased sharply between 1992 and 2005. Healthcare professionals should pay special attention to the potential risks of DDIs in these people, particularly if spironolactone is involved.

Renin-angiotensin system inhibitors, angiotensin I-converting enzyme gene insertion/deletion polymorphism, and cancer: the Rotterdam Study

BACKGROUND

Angiotensin I-converting enzyme (ACE) inhibitors, angiotensin II antagonists, and the ACE insertion/deletion (I/D) gene polymorphism all influence serum angiotensin II action. Because angiotensin II levels have been associated with cancer, the objective of the current epidemiologic study was to investigate whether renin-angiotensin system inhibitors and/or ACE genotypes were associated with an altered risk of colorectal, lung, breast, and prostate cancer.

METHODS

Data were obtained from the Rotterdam Study, a population-based, prospective cohort study with 7983 participants. Participants who had a history of 1 of the cancers of interest (n = 216) or who had a medication history <6 months (n = 88) were excluded, leaving 7679 participants, of whom the ACE genotypes could be assessed in 6670 individuals. The mean follow-up was 9.6 years, during which 730 incident cancers occurred. The effect of medication, ACE I/D genotypes, and their interaction on cancer risk and progression was studied by using Cox proportional hazard models.

RESULTS

Carriers of the high-activity genotype DD had an increased risk of breast cancer compared with low-activity II/ID genotype carriers (hazard ratio [HR], 1.47; 95% confidence interval [95% CI], 1.05-2.04), but no association was demonstrated for other cancers. DD carriers who were exposed to long-term and high-dose medication were at lower risk for cancer (HR, 0.28; 95% CI, 0.10-0.79). Short-term, high-dose users were at risk for colorectal cancer progression in the II/ID stratum (HR, 3.83; 95% CI, 1.67-8.79).

CONCLUSIONS

Renin-angiotensin system-inhibiting drugs seemed to protect against cancer in individuals with the DD genotype, which was associated with high levels of ACE.

Determinants of chronic benzodiazepine use in the elderly: a longitudinal study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* The risk of adverse events due to chronic benzodiazepine use is high in the elderly. * Cross-sectional studies have shown that increasing age, female gender and poor physical and mental health are associated with benzodiazepine use. * When users were re-examined some years later, chronic somatic disease, pain and stress seemed to contribute to the continuation of benzodiazepine use.

WHAT THIS STUDY ADDS

* This is the first longitudinal study that analyzed the determinants of new-onset chronic benzodiazepine use in community-dwelling elderly. * Symptoms of depression, hypertension, pain related joint complaints and the perception of poor physical health predicted new-onset chronic use. Living alone was found to decrease the risk of chronic use.

AIMS

The risk of adverse events due to chronic benzodiazepine use is high in the elderly. Clinicians need to be able to identify those persons who are at risk of chronic benzodiazepine use, but little is known about the determinants. This study determined social and health related factors that predict new-onset chronic benzodiazepine use in community-dwelling elderly.

METHODS

This study was embedded in an ongoing cohort study among 5364 persons aged >or=57 years. Drug-dispensing medication records were available for the period between 1991 and 2003. We defined chronic benzodiazepine use as use during at least 180 days in a period of 365 consecutive days. The association of various social, psychiatric and somatic variables with new-onset chronic benzodiazepine use was studied with a Cox proportional hazards analysis.

RESULTS

Symptoms of depression, hypertension, pain related joint complaints and the perception of poor physical health predicted new-onset chronic use. In the subsample of participants who had filled at least one prescription in the follow-up period, of these variables only pain related joint complaints increased the risk of new-onset chronic use. Living alone protected against chronic benzodiazepine use.

CONCLUSIONS

The elderly with poor mental and physical health are at an increased risk of chronic benzodiazepine use. Living alone was found to decrease the risk of chronic use, which suggests that social factors may determine drug usage patterns. Very few characteristics predicted chronic benzodiazepine use once patients had received their first prescription. For clinicians, identification of patients at high risk is therefore not straightforward.

Influence of the CYP2D6*4 polymorphism on dose, switching and discontinuation of antidepressants

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* Most antidepressants are metabolized by CYP2D6. The variant allele CYP2D6*4 is the main polymorphism resulting in reduced enzyme activity in Caucasians. * Reduced enzyme activity potentially leads to increased toxicity of antidepressants, but the relevance of genotyping for clinical practice is unclear. Most clinical studies suffer from small numbers of patients.

WHAT THIS STUDY ADDS

* This large population-based cohort study in 1198 elderly Dutch patients examines the influence of the CYP2D6*4 polymorphism on intolerability of antidepressants. * The risk of switching to another antidepressant in tricyclic antidepressant users is higher in poor metabolizers (PMs), but not in SSRI users. PMs require a lower maintenance dose of antidepressants compared with extensive metabolizers (EMs). * Antidepressants were initiated in a relatively low dose, with gradual dose increments thereafter, reducing the risk of adverse drug reactions. Therefore, the question remains whether genotyping prior to the start of antidepressant therapy contributes substantially to the optimization of pharmacotherapy.

AIMS

To study the effect of CYP2D6*4 on antidepressant dose, switching and discontinuation of therapy.

METHODS

The study consisted of all subjects in the Rotterdam Study, who received a first antidepressant prescription between April 1st 1991 and July 1st 2005 and for whom data on CYP2D6 genotype were available. Binary logistic regression was performed to study the association between CYP2D6*4 and switching to any other antidepressant or discontinuation of therapy within 45 days. The difference in mean antidepressant dose was compared between CYP2D6 genotypes using t-tests and repeated measurements analyses.

RESULTS

In users of tricyclic antidepressants (TCAs) the risk of switching to another antidepressant was significantly higher in poor metabolizers (PMs:*4/*4) compared with extensive metabolizers (EMs:*1/*1), with an adjusted OR of 5.77 (95% CI 1.59, 21.03; P = 0.01). In SSRI users there was no significant difference (OR 0.91; 95% CI 0.20, 4.15; P = 0.90). Heterozygous patients did not have an increased risk of switching in both TCA and SSRI users. The mean TCA dose was significantly lower in PMs than in EMs at the third and fourth prescription (difference 0.11 DDD, P = 0.03). In SSRI users the difference in mean dose between PMs and EMs was significant at the third prescription (0.17 DDD; P = 0.02).

CONCLUSIONS

The risk of switching to another antidepressant in TCA users is higher in PMs than in EMs. The maintenance doses of antidepressants were significantly lower in PMs. However, the question whether genotyping prior to the start of antidepressant therapy contributes substantially to the optimization of pharmacotherapy, requires further study.

The Rotterdam Study: objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in the Netherlands. The study targets cardiovascular, neurological, ophthalmological and endocrine diseases. As of 2008 about 15,000 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in some 600 research articles and reports (see http://www.epib.nl/rotterdamstudy). This article gives the reasons for the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

All-cause mortality associated with atypical and typical antipsychotics in demented outpatients

PURPOSE

To estimate the association between use of typical and atypical antipsychotics and all-cause mortality in a population of demented outpatients.

METHODS

The study cohort comprised all demented patients older than 65 years and registered in the Integrated Primary Care Information (IPCI) database, during 1996-2004. First, mortality rates were calculated during use of atypical and typical antipsychotics. Second, we assessed the association between use of atypical and typical antipsychotics and all-cause mortality through a nested case-control study in the cohort of demented patients. Each case was matched to all eligible controls at the date of death by age and duration of dementia. Odds ratios were estimated through conditional logistic regression analyses.

RESULTS

The crude mortality rate was 30.1 (95%CI: 18.2-47.1) and 25.2 (21.0-29.8) per 100 person-years (PY) during use of atypical and typical antipsychotics, respectively. No significant difference in risk of death was observed between current users of atypical and typical antipsychotics (OR = 1.3; 95%CI: 0.7-2.4). Both types of antipsychotics were associated with a significantly increased risk of death as compared to non-users (OR = 2.2, 1.2-3.9 for atypical antipsychotics; OR=1.7, 1.3-2.2 for typical antipsychotics).

CONCLUSIONS

Conventional antipsychotic drug should be included in the FDA's Public Health advisory, which currently warns only of the increased risk of death with the use of atypical antipsychotics in elderly demented persons.

The risk of myocardial infarction in patients with reduced activity of cytochrome P450 2C9

OBJECTIVE

The aim of the present follow-up study was to investigate whether the enzyme activity of the human cytochrome P450 (CYP) 2C9 isoenzyme is associated with myocardial infarction.

METHODS

We investigated whether the variant alleles CYP2C9*2 and CYP2C9*3 or the use of CYP2C9 substrates or inhibitors was associated with an increased risk of myocardial infarction in 2210 men and 3534 women from the Rotterdam Study, a prospective population-based cohort study of individuals aged 55 years or older.

RESULTS

In women, the use of CYP2C9 substrates or inhibitors was significantly associated with incident myocardial infarction with a hazard ratio of 2.48 (95% confidence interval: 1.55-3.96). Within the group of female carriers of a variant allele, the use of CYP2C9 substrates or inhibitors was associated with a fourfold increased risk of myocardial infarction (hazard ratio 3.86, 95% confidence interval: 1.93-7.75), as compared with non-use. Neither the use of CYP2C9 inhibitors or substrates nor the variant CYP2C9 alleles were associated with an increased risk of myocardial infarction in men.

CONCLUSIONS

Drugs that are metabolized by CYP2C9 increase the risk of myocardial infarction in women. This risk was even higher in women with allelic variants of CYP2C9 with reduced enzyme activity.

Hospitalisations and emergency department visits due to drug-drug interactions: a literature review

PURPOSE

Our objective was to evaluate the incidence of adverse patient outcomes due to drug-drug interactions (D-DIs), the type of drugs involved and the underlying reason. As a proxy for adverse patient outcomes, emergency department (ED) visits, hospital admissions and re-hospitalisations were assessed.

METHODS

A literature search in the Medline and Embase database (1990-2006) was performed and references were tracked. An overall cumulative incidence was estimated by dividing the sum of the cases by the sum of the study populations.

RESULTS

Twenty-three studies were found assessing the relationship between D-DIs and ED-visits, hospitalisations or re-hospitalisations. The studies with a large study size showed low incidences and vice versa. D-DIs were held responsible for 0.054% of the ED-visits, 0.57% of the hospital admissions and 0.12% of the re-hospitalisations. In the elderly population, D-DIs were held responsible for 4.8% of the admissions. Drugs most often involved were NSAIDs and cardiovascular drugs. The reasons for admissions or ED-visits, which were most often found were GI-tract bleeding, hyper- or hypotension and cardiac rhythm disturbances.

CONCLUSION

This review provides information on the overall incidence of D-DIs as a cause of adverse patient outcomes, although there is still uncertainty about the impact of D-DIs on adverse patient outcomes. Our results suggest that a limited number of drugs are involved in the majority of cases and that the number of reasons for admission as a consequence of D-DIs seems to be modest.