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

Determinants of DNA yield and purity collected with buccal cell samples

Buccal cells are an important source of DNA in epidemiological studies, but little is known about factors that influence amount and purity of DNA. We assessed these factors in a self-administered buccal cell collection procedure, obtained with three cotton swabs. In 2,451 patients DNA yield and in 1,033 patients DNA purity was assessed. Total DNA yield ranged from 0.08 to 1078.0 μg (median 54.3 μg; mean 82.2 μg ± SD 92.6). The median UV 260:280 ratio, was 1.95. Samples from men yielded significantly more DNA (median 58.7 μg) than those from women (median 44.2 μg). Diuretic drug users had significantly lower purity (median 1.92) compared to other antihypertensive drug users (1.95). One technician obtained significantly lower DNA yields. Older age was associated with lower DNA purity. In conclusion, DNA yield from buccal swabs was higher in men and DNA purity was associated with age and the use of diuretics

Determinants of DNA yield and purity collected with buccal cell samples

Buccal cells are an important source of DNA in epidemiological studies, but little is known about factors that influence amount and purity of DNA. We assessed these factors in a self-administered buccal cell collection procedure, obtained with three cotton swabs. In 2,451 patients DNA yield and in 1,033 patients DNA purity was assessed. Total DNA yield ranged from 0.08 to 1078.0 μg (median 54.3 μg; mean 82.2 μg ± SD 92.6). The median UV 260:280 ratio, was 1.95. Samples from men yielded significantly more DNA (median 58.7 μg) than those from women (median 44.2 μg). Diuretic drug users had significantly lower purity (median 1.92) compared to other antihypertensive drug users (1.95). One technician obtained significantly lower DNA yields. Older age was associated with lower DNA purity. In conclusion, DNA yield from buccal swabs was higher in men and DNA purity was associated with age and the use of diuretics

Feasibility of pharmacy-initiated pharmacogenetic screening for CYP2D6 and CYP2C19

PURPOSE: Our purpose was to investigate the feasibility of pharmacy-initiated pharmacogenetic (PGt) screening in primary care with respect to patient willingness to participate, quality of DNA collection with saliva kits, genotyping, and dispensing data retrieved from the pharmacy. METHODS: Polypharmacy patients aged >60 years who used at least one drug with Anatomical Therapeutic Chemical (ATC) code N06AA01-N06AX19 (antidepressants), A02BC01-A02BC05 (proton-pump inhibitors), N05AA01-N05AH04 (antipsychotics), or C07AB02 (metoprolol) in the preceding 2 years were randomly selected. DNA was collected with saliva kits and genotyped for CYP2D6 and CYP2C19 with the AmpliChip. Pharmacy dispensing records were retrieved and screened for drugs interacting with the patient's CYP2D6 and CYP2C19 genotype by using the evidence-based PGt guidelines from the Dutch Pharmacogenetics Working Group. RESULTS: Out of the 93 invited patients, 54 (58.1%) provided informed consent. Nine saliva samples (16.7%) contained too little DNA. Call rates for CYP2D6 and CYP2C19 were 93.3% and 100%, respectively. Frequencies of genotype-predicted phenotype were 2.4%, 38.1%, 54.8%, and 4.8% for CYP2D6 poor metabolizers (PM), intermediate metabolizers (IM), extensive metabolizers (EM), and ultrarapid metabolizers (UM) respectively. For CYP2C19 genotype-predicted phenotype, frequencies were 2.2%, 15.6%, and 82.2% for PM, IM, and EM, respectively. CONCLUSIONS: This study shows that pharmacy-initiated PGt screening is feasible for a primary care setting

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children

Pharmacogenetics of antihypertensive drug treatment - design and conduct of an observational study

Hypertension is a major public health hazard, because of its high prevalence and strong positive association with cardiovascular diseases. Despite the availability of a variety of effective antihypertensive drugs, inadequate control of blood pressure is common in hypertensive patients, and responsible for a large proportion of the burden of stroke and myocardial infarction (MI) in the population. The aim of this thesis was to assess the feasibility of setting up a large retrospective population based pharmacogenetic study and to gain more insight into the interactions between antihypertensive drugs and candidate gene polymorphisms on the risk of MI. Firstly, we focused on methodological issues in a pharmacogenetic study. Our study shows that it is feasible to set up a large retrospective study by collecting information through community pharmacies and patients themselves and to build a large DNA data bank. Furthermore, we found that fear for genetic screening does not seem to have a large impact on the willingness to participate. The main reason mentioned for non participation was health problems. Females were less willing to participate just like older patients. DNA samples from men yielded more DNA than those from women whereas DNA purity was the same for both men and women. Diuretic drug use, older age and laboratory personnel were associated with lower DNA purity. Secondly, we examined different drug-gene interactions. Among subjects with the ?-adducin G460W variant the risk of MI was similar among thiazide users compared to users of other antihypertensives, whereas among wild type carriers this risk was significantly lower. However, the interaction between current use of diuretics and the ?-adducin polymorphism was not statistically significantly increased on the multiplicative scale. The interaction between the eNOS G894T polymorphism and the use of calcium antagonists on the risk of MI was studied in a Dutch study population and in a US replication study population. Homozygous T-allele carriers using dihyropyridines had a higher risk of MI in the Dutch study population, but not in the US study population. Homozygous G-allele carriers did not have an increased risk in the Dutch study population, but did have in the US study population. We found a statistically significant interaction in the Dutch study but not in a US replication study. In both populations no significant interactions between the eNOS variant and diltiazem or verapamil was found. Finally, we examined the effects of renin-angiotensin-system polymorphisms on the risk of MI among users of renin-angiotensin-system inhibitors. In the patients treated with ACE-inhibitors the largest risk reduction was found in patients carrying the ACE 4656 G-allele (GC and GG) compared to patients with the CC genotype. The risk of MI was significantly reduced in current users of ACE-inhibitors, who used dosages lower than the equivalent of 1 defined daily dose, with the AGTR1 1166AC or AA genotype compared to users of ACE-inhibitors with the AGTR1 1166CC genotype. The ACE G4656C polymorphism did not modify the effectiveness of AT II antagonists on the risk of MI. No interaction was found with the ACE T3892C and the AGT C235T polymorphism. This may affect treatment of hypertension in the future when other studies confirmed these findings

Pharmacogenetics of antihypertensive drug treatment - design and conduct of an observational study

Hypertension is a major public health hazard, because of its high prevalence and strong positive association with cardiovascular diseases. Despite the availability of a variety of effective antihypertensive drugs, inadequate control of blood pressure is common in hypertensive patients, and responsible for a large proportion of the burden of stroke and myocardial infarction (MI) in the population. The aim of this thesis was to assess the feasibility of setting up a large retrospective population based pharmacogenetic study and to gain more insight into the interactions between antihypertensive drugs and candidate gene polymorphisms on the risk of MI. Firstly, we focused on methodological issues in a pharmacogenetic study. Our study shows that it is feasible to set up a large retrospective study by collecting information through community pharmacies and patients themselves and to build a large DNA data bank. Furthermore, we found that fear for genetic screening does not seem to have a large impact on the willingness to participate. The main reason mentioned for non participation was health problems. Females were less willing to participate just like older patients. DNA samples from men yielded more DNA than those from women whereas DNA purity was the same for both men and women. Diuretic drug use, older age and laboratory personnel were associated with lower DNA purity. Secondly, we examined different drug-gene interactions. Among subjects with the ?-adducin G460W variant the risk of MI was similar among thiazide users compared to users of other antihypertensives, whereas among wild type carriers this risk was significantly lower. However, the interaction between current use of diuretics and the ?-adducin polymorphism was not statistically significantly increased on the multiplicative scale. The interaction between the eNOS G894T polymorphism and the use of calcium antagonists on the risk of MI was studied in a Dutch study population and in a US replication study population. Homozygous T-allele carriers using dihyropyridines had a higher risk of MI in the Dutch study population, but not in the US study population. Homozygous G-allele carriers did not have an increased risk in the Dutch study population, but did have in the US study population. We found a statistically significant interaction in the Dutch study but not in a US replication study. In both populations no significant interactions between the eNOS variant and diltiazem or verapamil was found. Finally, we examined the effects of renin-angiotensin-system polymorphisms on the risk of MI among users of renin-angiotensin-system inhibitors. In the patients treated with ACE-inhibitors the largest risk reduction was found in patients carrying the ACE 4656 G-allele (GC and GG) compared to patients with the CC genotype. The risk of MI was significantly reduced in current users of ACE-inhibitors, who used dosages lower than the equivalent of 1 defined daily dose, with the AGTR1 1166AC or AA genotype compared to users of ACE-inhibitors with the AGTR1 1166CC genotype. The ACE G4656C polymorphism did not modify the effectiveness of AT II antagonists on the risk of MI. No interaction was found with the ACE T3892C and the AGT C235T polymorphism. This may affect treatment of hypertension in the future when other studies confirmed these findings