Coronary artery disease risk reclassification by a new acoustic-based score

To determine the potential of a non-invasive acoustic device (CADScor®System) to reclassify patients with intermediate pre-test probability (PTP) and clinically suspected stable coronary artery disease (CAD) into a low probability group thereby ruling out significant CAD. Audio recordings and clinical data from three studies were collected in a single database. In all studies, patients with a coronary CT angiography indicating CAD were referred to coronary angiography. Audio recordings of heart sounds were processed to construct a CAD-score. PTP was calculated using the updated Diamond-Forrester score and patients were classified according to the current ESC guidelines for stable CAD: low < 15%, intermediate 15–85% and high > 85% PTP. Intermediate PTP patients were re-classified to low probability if the CAD-score was ≤ 20. Of 2245 patients, 212 (9.4%) had significant CAD confirmed by coronary angiography ( ≥ 50% diameter stenosis). The average CAD-score was higher in patients with significant CAD (38.4 ± 13.9) compared to the remaining patients (25.1 ± 13.8; p < 0.001). The reclassification increased the proportion of low PTP patients from 13.6% to 41.8%, reducing the proportion of intermediate PTP patients from 83.4% to 55.2%. Before reclassification 7 (3.1%) low PTP patients had CAD, whereas post-reclassification this number increased to 28 (4.0%) (p = 0.52). The net reclassification index was 0.209. Utilization of a low-cost acoustic device in patients with intermediate PTP could potentially reduce the number of patients referred for further testing, without a significant increase in the false negative rate, and thus improve the cost-effectiveness for patients with suspected stable CAD.

Baseline findings of the population-based, randomized, multifaceted Danish cardiovascular screening trial (DANCAVAS) of men aged 65–74 years

Background

The challenge of managing age-related diseases is increasing; routine checks by the general practitioner do not reduce cardiovascular mortality. The aim here was to reduce cardiovascular mortality by advanced population-based cardiovascular screening. The present article reports the organization of the study, the acceptability of the screening offer, and the relevance of multifaceted screening for prevention and management of cardiovascular disease.

Methods

Danish men aged 65–74 years were invited randomly (1 : 2) to a cardiovascular screening examination using low-dose non-contrast CT, ankle and brachial BP measurements, and blood tests.

Results

In all, 16 768 of 47 322 men aged 65–74 years were invited and 10 471 attended (uptake 62·4 per cent). Of these, 3481 (33·2 per cent) had a coronary artery calcium score above 400 units. Thoracic aortic aneurysm was diagnosed in the ascending aorta (diameter 45 mm or greater) in 468 men (4·5 per cent), in the arch (at least 40 mm) in 48 (0·5 per cent) and in the descending aorta (35 mm or more) in 233 (2·2 per cent). Abdominal aortic aneurysm (at least 30 mm) and iliac aneurysm (20 mm or greater) were diagnosed in 533 (5·1 per cent) and 239 (2·3 per cent) men respectively. Peripheral artery disease was diagnosed in 1147 men (11·0 per cent), potentially uncontrolled hypertension (at least 160/100 mmHg) in 835 (8·0 per cent), previously unknown atrial fibrillation confirmed by ECG in 50 (0·5 per cent), previously unknown diabetes mellitus in 180 (1·7 per cent) and isolated severe hyperlipidaemia in 48 men (0·5 per cent).

In all, 4387 men (41·9 per cent), excluding those with potentially uncontrolled hypertension, were referred for additional cardiovascular prevention. Of these, 3712 (35·5 per cent of all screened men, but 84·6 per cent of those referred) consented and were started on medication.

Conclusion

Multifaceted cardiovascular screening is feasible and may optimize cardiovascular disease prevention in men aged 65–74 years. Uptake is lower than in aortic aneurysm screening.

The DanCavas Pilot Study of Multifaceted Screening for Subclinical Cardiovascular Disease in Men and Women Aged 65-74 Years

OBJECTIVE/BACKGROUND

This pilot study of a large population based randomised screening trial investigated feasibility, acceptability, and relevance (prevalence of clinical and subclinical cardiovascular disease [CVD] and proportion receiving insufficient prevention) of a multifaceted screening for CVD.

METHODS

In total, 2060 randomly selected Danish men and women aged 65-74 years were offered (i) low dose non-contrast computed tomography to detect coronary artery calcification (CAC) and aortic/iliac aneurysms; (ii) detection of atrial fibrillation (AF); (iii) brachial and ankle blood pressure measurements; and (iv) blood levels of cholesterol and hemoglobin A1c. Web based self booking and data management was used to reduce the administrative burden.

RESULTS

Attendance rates were 64.9% (n = 678) and 63.0% (n = 640) for men and women, respectively. In total, 39.7% received a recommendation for medical preventive actions. Prevalence of aneurysms was 12.4% (95% confidence interval [CI] 9.9-14.9) in men and 1.1% (95% CI 0.3-1.9) in women, respectively (p < .001). A CAC score > 400 was found in 37.8% of men and 11.3% of women (p < .001), along with a significant increase in median CAC score with age (p = .03). Peripheral arterial disease was more prevalent in men (18.8%, 95% CI 15.8-21.8) than in women (11.2%, 95% CI 8.7-13.6). No significant differences between the sexes were found with regard to newly discovered AF (men 1.3%, women 0.5%), potential hypertension (men 9.7%, women 11.5%), hypercholesterolemia (men 0.9%, women 1.1%) or diabetes mellitus (men 2.1%, women 1.3%).

CONCLUSION

Owing to the higher prevalence of severe conditions, such as aneurysms and CAC ≥ 400, screening for CVD seemed more prudent in men than women. The attendance rates were acceptable compared with other screening programs and the logistical structure of the screening program proved successful.

Research in the Danish health service system: completeness and validity of prescription data, illustrated by analysis of utilization of oral anticoagulants

We studied the utilization of oral anticoagulants and the degree of completeness and validity of some key research variables from the Danish health service in the county of North Jutland (482 000 inhabitants), studying the records of 12 855 prescriptions of oral anticoagulants during 1991 and 1992. The utilization of oral anticoagulants showed an increase of 16% from 1991 to 1992, when 0.3% of all women and 0.4% of all men were treated during one year. The increase was less than expected based on newly introduced indications for treatment of atrial fibrillation. The following variables were studied: the name (ATC commodity number) and amount of the prescribed drug, the defined daily dose, the personal registration number of the patient, type of prescription (e.g. in writing or by telephone), number of repeat prescriptions, date of prescription issued by the doctor, the registration number of the GP or hospital department (if the prescription is made by a hospital doctor) and date of expedition from the pharmacy. The number of wrong and missing data was less than 1%. The study suggests that Danish prescription information is of such quality that it can be used for pharmacoepidemiological studies.

Variation in antibiotic prescribing costs in Danish general practice: an epidemiological pharmaco-economic analysis

Based on 49,621 prescriptions during a period of 6 months we analysed factors relevant to the use of antibiotics among 137 general practitioners based on the reimbursement by the Danish Health Service. The background population constituted 167,105 adults and 42,392 children. The Danish Health Service refunds either 50 or 75% of the costs of antibiotics. The mean reimbursement per prescription was 96.45 DKK ranging between 56.10 DKK and 141.95 DKK. The total prescribed amount of antibiotics per GP measured in defined daily dose (DDD), the reimbursement per prescription for all other drugs than antibiotics, the proportion of patients above the age of 65 years and the number of cultures per 1,000 patients were positively associated with the reimbursement per prescription of antibiotics. The four variables explained 29% of the variation. The number of cultures and consultations per general practitioner were positively associated with the total reimbursement for antibiotics per general practitioner, while the number of throat swabs per general practitioner was negatively associated. The prescribed amount of DDD per prescription and the reimbursement per DDD of antibiotics contributed almost equally to the variation in reimbursement for each prescription. The study thus shows that the doctors prescribing the highest amounts of antibiotics measured as DDD also choose the most expensive drugs and that this choice of expensive drugs seems to be a general trend independent of the ATC group.

The risk of limb deficiencies and other congenital abnormalities in children exposed in utero to calcium channel blockers

AIM

Calcium channel blockers given to pregnant rats have shown an increased prevalence of digital and limb defects and their safety in pregnant women has thus been questioned. We examined the risk of malformations following exposure in utero to calcium channel blockers.

METHOD

We conducted a nationwide case-control study based on the Hungarian Case-Control Surveillance of Congenital Abnormalities and identified 22,865 cases with congenital abnormalities and 31,151 population controls during the period 1980-1996. Data on drug exposure were obtained from official questionnaires and obligatory prenatal care logbooks.

RESULTS

Among the cases, 586 mothers (2.6%) had been exposed to calcium channel blockers during pregnancy compared with 907 controls (2.4%). The overall prevalence ratios for 17 congenital abnormalities varied between 1.1 and 1.4, and there was no significant increased risk of limb deficiencies or other congenital abnormalities.

CONCLUSION

Our data did not indicate an increased prevalence of congenital abnormalities in offspring exposed to calcium channel blockers in utero.

The association of indicators of fetal growth with visual acuity and hearing among conscripts

Impaired fetal growth is associated with increased susceptibility to several chronic diseases. We studied the association between birth weight, indicators of disproportional fetal growth, and impaired visual acuity and hearing in 4,300 conscripts from a well-defined region in Denmark from August 1, 1993, to July 31, 1994. From the standard health examination for conscripts, we obtained data on sight based on the Snellen's chart and data on hearing acuity based on audiometry. By means of record linkage, we obtained data on outcomes for the conscripts at birth from the Medical Birth Registry. From this registry, we have data on birth weight, gestational age, and birth length that were recorded from existing computerized registers based on the records of midwives. A birth weight of less than 3,000 gm and a body mass index at birth of less than 3.4 were associated with reduced visual acuity and impaired hearing. The results could be due to fetal brain programming or due to confounding, by early birth trauma or other factors.

Effect of home and hospital delivery on long-term cognitive function

We examined the relation between place of birth and cognitive function in young adult life in a historical cohort study based upon birth data from the computerized Danish Medical Birth Registry and cognitive function as measured at time of drafting for military service in two Danish counties. The cohort included 4,296 Danish conscripts born between 1973 and 1976, 123 born at home and 4,173 born in hospital or at a birth clinic. Cognitive function was measured by the Boerge Prien test in men, 18 to 20 years of age. The highest possible score is 78. The mean Boerge Prien test score was 43.1 for conscripts born in specialized hospital departments, 2.4 higher for conscripts born in a birth clinic (95% confidence interval = 0.9-4.0), and 2.1 lower for conscripts born at home (95% confidence limits = -3.8 to -0.4) after adjusting for birth weight, length at birth, birth order, gestational age, maternal age, and marital and occupational status. Our findings raise the possibility that home birth can lead to lower cognitive function in adulthood; however, from our data we could not distinguish between planned and unplanned births at home.

Risk of upper gastrointestinal bleeding associated with use of low-dose aspirin

OBJECTIVE

Aspirin products are known to cause irritation and injury to the gastric mucosa. We examined the risk of hospitalization for upper gastrointestinal bleeding with use of low-dose aspirin.

METHODS

This was a cohort study based on record linkage between a population-based prescription database and a hospital discharge registry in North Jutland County, Denmark, from January 1, 1991, to December 31, 1995. Incidence rates of upper gastrointestinal bleeding in 27,694 users of low-dose aspirin were compared with the incidence rates in the general population in the county.

RESULTS

A total of 207 exclusive users of low-dose aspirin experienced a first episode of upper gastrointestinal bleeding with admission to the hospital during the study period. The standardized incidence rate ratio was 2.6 (95% confidence interval, 2.2-2.9), 2.3 in women and 2.8 in men. The standardized incidence rate ratio for combined use of low-dose aspirin and other nonsteroidal anti-inflammatory drugs was 5.6 (95% confidence interval, 4.4-7.0). The risk was similar among users of noncoated low-dose aspirin (standardized incidence rate ratio, 2.6; 95% confidence interval, 1.8-3.5) and coated low-dose aspirin (standardized incidence rate ratio, 2.6; 95% confidence interval, 2.2-3.0).

CONCLUSIONS

Use of low-dose aspirin was associated with an increased risk of upper gastrointestinal bleeding, with still higher risks when combined with other nonsteroidal anti-inflammatory drugs. Enteric coating did not seem to reduce the risk. The findings from this observational study raise the possibility that prophylactic use of low-dose aspirin may convey an increased risk of gastrointestinal bleeding, which may offset some of its benefits.

Risk of upper gastrointestinal bleeding associated with use of low-dose aspirin

OBJECTIVE

Aspirin products are known to cause irritation and injury to the gastric mucosa. We examined the risk of hospitalization for upper gastrointestinal bleeding with use of low-dose aspirin.

METHODS

This was a cohort study based on record linkage between a population-based prescription database and a hospital discharge registry in North Jutland County, Denmark, from January 1, 1991, to December 31, 1995. Incidence rates of upper gastrointestinal bleeding in 27,694 users of low-dose aspirin were compared with the incidence rates in the general population in the county.

RESULTS

A total of 207 exclusive users of low-dose aspirin experienced a first episode of upper gastrointestinal bleeding with admission to the hospital during the study period. The standardized incidence rate ratio was 2.6 (95% confidence interval, 2.2-2.9), 2.3 in women and 2.8 in men. The standardized incidence rate ratio for combined use of low-dose aspirin and other nonsteroidal anti-inflammatory drugs was 5.6 (95% confidence interval, 4.4-7.0). The risk was similar among users of noncoated low-dose aspirin (standardized incidence rate ratio, 2.6; 95% confidence interval, 1.8-3.5) and coated low-dose aspirin (standardized incidence rate ratio, 2.6; 95% confidence interval, 2.2-3.0).

CONCLUSIONS

Use of low-dose aspirin was associated with an increased risk of upper gastrointestinal bleeding, with still higher risks when combined with other nonsteroidal anti-inflammatory drugs. Enteric coating did not seem to reduce the risk. The findings from this observational study raise the possibility that prophylactic use of low-dose aspirin may convey an increased risk of gastrointestinal bleeding, which may offset some of its benefits.

Cancer risk and mortality in users of calcium channel blockers. A cohort study

BACKGROUND

Data regarding the association between the use of calcium channel blockers and cancer risk have been conflicting. In the current study, the authors examined the cancer risk and mortality in users of calcium channel blockers in North Jutland County, Denmark.

METHODS

The authors conducted a cohort study using record linkage between a population-based prescription database, the Danish Cancer Registry, and the Danish Death Registry including 23, 167 users of calcium channel blockers who received >/=2 prescriptions between January 1, 1989 and December 31, 1995. The authors calculated the standardized incidence ratios and standard mortality ratios for cancer, along with corresponding 95% confidence intervals (95% CI).

RESULTS

Overall, 967 incident cases of cancer occurred, resulting in a standardized incidence ratio of 1.04 (95% CI, 0.98-1.11). There was a slightly elevated nonsignificant risk of tobacco-related cancer. No increased risk of breast or colon carcinoma was observed. The cancer mortality was close to that expected in the background population (standardized mortality ratio of 0.97; 95% CI, 0.89-1.04).

CONCLUSIONS

This large-scale, population-based cohort study adds to the increasing evidence indicating no substantial association between the use of calcium channel blockers and the incidence rate of cancer or cancer mortality.

[Antibiotic pre-hospital treatment and the course of meningococcal disease]

The aim of the study was to assess the effect of pre-hospital antibiotic treatment given by general practitioners to patients with meningococcal disease. It was carried out as a 16-year population-based historical follow-up study based on referral letters and hospital records in the County of North Jutland, Denmark, and included 320 patients with meningococcal disease, of whom 302 were examined by a general practitioner before admission to hospital. The main outcome measure was death. We found that 44 patients (14.6%) were given antibiotic treatment by the referring general practitioner. Nine of these (20.5%) died, compared with 16 (6.2%) patients who did not receive pre-hospital antibiotic treatment. The presence of skin bleeding, petechiae and impaired consciousness were strongly associated with case fatality. Even after adjustment for these variables the odds ratio for death in patients treated with antibiotics was high (3.2; 95% CI 0.9-10.6). In the 15 patients with skin bleeding (ecchymoses, suggillations) the case fatality rate was 100% in patients treated with antibiotics, and 50% in patients who did not receive antibiotics before hospitalization. It is concluded that pre-hospital treatment is mainly given to the most severe cases with expected high case fatality, and this confounding by indication was probably not fully adjusted for with the available data. The results contradict previous findings and provide reason to doubt the benefit of pre-hospital antibiotic treatment in patients with meningococcal disease.

[Incidence of cancer after primary deep venous thrombosis or pulmonary embolism]

We report a nationwide study based on a cohort of patients with a thromboembolic event (TE) defined as deep venous thrombosis and/or pulmonary embolism identified from the Danish National Registry of Patients from 1977 to 1993. Cancer occurrence in the cohort was determined by linkage to the Danish Cancer Registry. Expected number of cancer cases was estimated from age, sex and site-specific incidence rates. A total of 26,653 TE-cases were identified. We observed 1737 cases of cancer versus 1371 expected (SIR 1.3; 95% CI, 1.21 to 1.33). The risk was particularly high during the first months of follow-up, but declined rapidly hereafter to a constant level slightly above 1.0 one year after the TE. Forty percent of patients diagnosed with cancer within one year from the hospitalization for TE had distant metastases at the time of cancer diagnosis. The observed risk pattern provides evidence that most often a preclinical cancer gives rise to a subsequent TE. An aggressive search for hidden cancer in patients with TE is not warranted.

Low birth weight and preterm delivery as risk factors for asthma and atopic dermatitis in young adult males

Gestational factors have been hypothesized to play a role in the susceptibility to asthma and atopic dermatitis. We examined whether fetal growth was associated with asthma and atopic dermatitis separately in a population of 4,795 male conscripts born between 1973 and 1975 in Denmark. The prevalence of asthma was 4.7%. The prevalence odds ratio of asthma in conscripts with a birth weight below 2,501 g was 1.5 (95% confidence interval = 0.7-3.1) compared with conscripts with a birth weight of 3,001-3,500 g, adjusted for gestational age and potential confounders. The adjusted prevalence odds ratio among conscripts born before 34 gestational weeks was 0.8 (95% confidence interval = 0.3-2.0) compared with conscripts born at term. The prevalence of atopic dermatitis was 1.0%. The prevalence odds ratio of atopic dermatitis among those with a birth weight below 2,501 g was 3.0 (95% confidence interval = 0.8-11.9) compared with those whose birth weight was between 3,001 and 3,500 g. Men whose gestational age had been below 34 weeks had an adjusted prevalence odds ratio of 0.3 (95% confidence interval = 0.0-3.1). These findings indicate that fetal growth retardation rather than preterm delivery of male infants is the main gestational factor underlying the associations but does not explain the apparent increase over time of asthma or atopic diseases.

A population-based cohort study of birth and neonatal outcome in older primipara

OBJECTIVES

To examine the risk of adverse birth outcome in older primiparous women.

METHODS

We identified 14,676 primiparae of 20 years of age or more from 1991 to 1996 using the Birth Registry in the North Jutland County, Denmark. We evaluated the risk of adverse birth outcome in the primiparous women aged 30-34 years and above 35 years using the primiparae aged 20-29 years at time of birth as reference.

RESULTS

The risks of induced labor, perineotomy, stimulating contraction and vacuum extraction were significantly higher (adjusted odds ratio: 1.3 to 1.7) in the primiparae of 35 years or more. The odds ratio for cesarean section delivery was 2.1 (95% confidence interval: 1.7-2.6) and the odds ratio for delivering a low birth weight child among the primiparae of 35 years or more was 2.2 (95% confidence interval: 1.4-3.3) compared with the primiparae of 20-29 years of age. These risk estimates were independent of women's infertility treatment history.

CONCLUSIONS

A negative effect of maternal age on birth and neonatal outcome may be seen even after 30 years of age and is partly related to chronic diseases. However, it is impossible to rule out selection bias, but the actual risk must be taken into consideration in antenatal care.

Pregnancy outcome following prescription for sumatriptan

BACKGROUND

Some 2.5% of fertile Danish women use sumatriptan, and the drug is also taken during pregnancy. Although sumatriptan reacts selectively in brain vessels, the possibility of reactions with placental blood flow and uterotonic activity cannot be ruled out. The aim of our study was to examine the association between sumatriptan exposure during pregnancy and the risk of preterm delivery and low birth weight.

METHODS

Data from the Pharmaco-Epidemiological Prescription Database of North Jutland county regarding all women who had given birth in the county of North Jutland from 1991 to 1996 were linked to the Danish Medical Birth Registry. Women who were exposed to sumatriptan during pregnancy were identified (n = 34), and using logistic regression models their pregnancy outcome was compared with two groups of pregnant women: (1) healthy women (n = 15 955) and (2) migraine controls (n = 89), defined as migraine patients who did not redeem prescriptions for migraine treatment during pregnancy.

RESULTS

The risk of preterm delivery was elevated among women exposed to sumatriptan compared with migraine controls (odds ratio [OR] 6.3, 95% confidence interval [CI] 1.2-32.0) and healthy women (OR 3.3, 95% CI 1.3-8.5). The odds ratio for having a newborn with a low birth weight was increased (OR 3.0, 95% CI 1.3-7.0) for all migraine patients who delivered at term (n=115) compared with the outcome of healthy pregnancies.

CONCLUSIONS

We found that sumatriptan exposure during pregnancy was associated with an increased risk of preterm delivery and low birth weight. These findings may be due to drug exposure, but they may also reflect the impact of disease severity rather than the treatment itself, or confounding, or chance.

Waist circumference and body mass index as predictors of elevated alanine transaminase in Danes aged 30 to 50 years

INTRODUCTION

We examined whether waist circumference and waist-to-hip circumference ratio were a better predictor for elevated alanine transaminase level than body mass index.

METHODOLOGY

In a cross-sectional survey we examined body mass index, waist circumference, waist-to-hip ratio, alcohol consumption, and alanine transaminase level in a random sample of 903 men and women aged 30 to 50 years from The Ebeltoft Health Promotion Project in Denmark.

RESULTS

Body mass index, waist circumference and waist-to-hip ratio explained an approximate 12% variation in alanine transaminase in men and 4% in women, whereas waist-to-hip circumference ratio explained a 2% variation in women. The risk of elevated alanine transaminase level in men, calculated as odds ratio, with a body mass index (kg/m2) above 30, or a waist circumference above 102 cm, or a waist-to-hip circumference ratio above 0.9 was 9.3 (95% confidence interval [CI], 3.6-24.1), 5.6 (95% CI, 2.5-12.5) and 2.7 (95% CI, 1.3-5.3) respectively, but there was no elevated risk among women.

CONCLUSIONS

Waist circumference and body mass index were both predictors in men. Waist-to-hip ratio was also a predictor in men, but not as strong a predictor as waist circumference and body mass index. No association was found in women. This difference is probably explained by differences in the accumulation of intra-abdominal adipose tissue among men and women with the same degree of obesity.

Long-term follow-up of cognitive outcome after breech presentation at birth

Studies of long-term consequences of birth in breech presentation are sparse. Therefore, we conducted a cohort study linking birth registry data with data collected during evaluation for military service in 4,298 conscripts born between 1973 and 1976. The cognitive functions were measured with the Boerge Prien IQ test. A total of 164 conscripts were born in breech presentation and 70 (42.7%) of these were delivered after Caesarean section. The mean Boerge Prien test score was 43.2 among men born in cephalic presentation and 39.9 among those born in breech presentation for a difference of 3.3 (95% confidence interval = 1.8-4.7). The negative association between breech presentation and cognitive outcome persisted after stratifying by Caesarean section and after adjustment for confounders. It also persisted when we restricted the analyses to term singleton pregnancies.

Prescribing during pregnancy and lactation with reference to the Swedish classification system. A population-based study among Danish women

AIM

To assess the current prescribing pattern for 15,756 primiparae before, during, and after their pregnancies with reference to fetal and neonatal risk.

METHOD

A prescription database study with linkage to The Danish Medical Birth Registry from 1991 to 1996. The drug subsidy system in Danish retail pharmacies, made it possible to identify prescriptions by individual use. All 34,334 prescriptions were set against the Swedish classification of risk of drug use in pregnancy and lactation.

RESULTS

During pregnancy, safe (group A), potentially harmful (group B3, C, and D), and non-classifiable drugs accounted for 40.9%, 26.6% and 28.7% respectively. The proportion of women who redeemed drugs was 29.2%, 8.6%, 18.7% and 0.9% from drug groups A, B, C and D respectively. The proportion of prescriptions from high risk groups declined during the course of pregnancy. Postpartum, safe drugs (group I and II), drugs with possible harmful neonatal effects (group III), and non-classifiable drugs accounted for 43.5%, 4.8%, and 35.8% of the prescriptions, respectively.

CONCLUSION

According to the Swedish classification system, we found that during pregnancy and lactation a high proportion of Danish women were exposed to one or more drugs in high risk groups; furthermore, knowledge regarding their safety for the fetus and neonate was limited for a large proportion of the prescriptions. Current evidence about long-term effects of prenatal exposure stresses the need for long-term follow-up of health and development among exposed children.

Risk of malformations and other outcomes in children exposed to fluconazole in utero

AIM

Fluconazole is an active drug systematically used in the oral treatment of vaginal candidiasis and other fungal diseases. We examined the risk of malformations and other birth outcomes following pregnancy related exposures.

METHOD

From 1 January 1991 to 31 December 1996 we identified 165 women who had taken fluconazole just before or during pregnancy in the Pregnancy Outcome Section of the North Jutland Pharmacoepidemiological Prescription Database, Denmark, which is linked to the Danish Medical Birth Registry. We compared their birth outcomes (malformation, low birth weight and preterm delivery) with the outcomes among 13 327 women who did not receive any prescriptions during their pregnancies.

RESULTS

The prevalence of malformation was 3.3% (four cases) among the 121 women, who had used fluconazole in the first trimester, and 5.2% (697 cases) in offspring to controls (odds ratio: 0.65, 95% confidence limits: 0.24-1.77). Furthermore, we did not find any significantly elevated risk of preterm delivery (odds ratio: 1.17, 95% confidence limits: 0.63-2.17) and low birth weight (odds ratio: 1.19, 95% confidence limits: 0.37-3.79).

CONCLUSION

The study showed no increased risk of congenital malformations, low birth weight or preterm birth in offspring to women who had used single dose fluconazole before conception or during pregnancy.

Diffusion of new drugs in Danish general practice

OBJECTIVES

There is a large variation in implementing research findings in clinical practice. We examined whether the concept of early or late adopters is universal for the diffusion of all new drugs, and whether it is associated with non-scientific factors in general practice.

METHODS

We identified all prescriptions for five new drugs from the population-based prescription database in North Jutland County, Denmark (490000 inhabitants) from 1993 to 1996, and calculated the period from release of the drugs to the issuing of the first prescription by each GP. Logistic regression was performed to predict early or late prescribing from physician characteristics, practice activity and the number of prescriptions, adjusted for age and sex.

RESULTS

The distributions of the diffusion time of the drugs by 95 solo practitioners were asymmetrical, with a long upper tail representing the late prescribers. The shape and slope of the diffusion curve were highly drug dependent. There was poor agreement of the three adopter categories (early, intermediate and late prescribers) between the five drugs (kappa < 0.35), but being a late prescriber was the most consistent condition. Late prescribing of tramadol, compared with intermediate prescribing, was associated with female physicians (odds ratio (OR) 5.7; 95% CI 1.5-21.3), smaller list size (OR 0.1; 95% CI 0.0-0.8), a strong general restrictive attitude to pharmacotherapy (OR 0.07; 95% CI 0.01-0.68) and a tendency to lower diagnostic activity per patient (OR 0.4; 95% CI 0.1-1.9).

CONCLUSIONS

The slope and shape of the diffusion curve are both dependent on physician and drug characteristics, but late prescribers share some common characteristics.

Historical cohort study of in utero exposure to uterotonic drugs and cognitive function in young adult life

OBJECTIVE

To examine whether in utero exposure to uterotonic drugs effects cognitive performance in draft-age men.

DESIGN

Historical cohort study based on birth registry data and cognitive function measured during evaluations for military service.

SUBJECTS

4300 Danish conscripts born between 1973 and 1975.

MAIN OUTCOME MEASURES

MEAN SCORE IN THE BOERGE PRIEN TEST OF COGNITIVE FUNCTION: score is the number of correct answers to 78 questions and correlates with the full scale intelligence quotient.

RESULTS

The mean Boerge Prien score was similar for those exposed (n=1011) to uterotonic drugs and those not exposed (n=3289), 43.1 versus 42.9 after adjustment for confounders.

CONCLUSION

Our data indicate that exposure to uterotonic drugs does not affect cognitive function 20 years later.

Birth weight and length as predictors for adult height

Adult height has been found to be inversely associated with mortality. Recently, it has been suggested that growth in utero is linked with adult risk of several chronic diseases. The authors examined possible associations between birth weight, birth length, and adult height in young Danish men. They conducted the study in the fifth conscription district of Denmark including all the men born after January 1, 1973 who were residents in the study area during the period August 1, 1993 to July 31, 1994. The Danish Medical Birth Register contains information on all births in Denmark since January 1, 1973. Data on height from the Conscription Register were linked to the Danish Medical Birth Register in 4,300 conscripts examined. Nearly all Danish men have to register with the draft board around age 18 years of age where they undergo a physical examination. There was a strong positive association between birth weight and adult height; for subjects with birth weight < or = 2,500 g, mean height was 175.7 cm, while for those with birth weight > or = 4,501 g, mean height was 184.1 cm. A positive association was also found between birth length and adult height. For subjects with birth length < 47 cm, mean adult height was 175.2 cm, increasing to 184.3 cm at birth length > 56 cm. The associations between birth length and adult height persisted after adjustment for birth weight, gestational age, and other confounders, while the associations between birth weight and adult height almost disappeared when adjusting for birth length and the same confounders. Genetic and/or environmental factors operating both during the pre- and postnatal period may be responsible for the association between birth length and adult height.

A population-based study of antibiotic prescriptions for Danish children

BACKGROUND

The aim of the study was to examine the use of systemic and topical antibiotics in relation to age and sex in Danish children.

METHODS

We used the Pharmacoepidemiological Prescription Database to identify the individual prescriptions of antibiotics provided for all 0-to 15-year-old children in North Jutland County, Denmark, during 1997. The population was approximately 95000 children.

RESULTS

We identified 44640 prescriptions for systemic antibiotics. The annual prescription rate was highest in the 1- to 2-year-olds, with 945 prescriptions/1000 children/year. One-half of these children received at least 1 prescription, and 12% received 3 or more prescriptions. Among the 11- to 15-year-old children 17% received one or more prescriptions. Overall 88% of the prescriptions were penicillins and 10% were macrolides. In children younger than 3 years 57% of prescriptions were for broad spectrum penicillins, but in children older than 6 years penicillin V was the most frequently used antibiotic. We identified 12 661 prescriptions for topical antibiotics used in eye infections. The prescription rate peaked in the 1- to 2-year-old children, one-third of whom received at least 1 prescription.

CONCLUSIONS

Almost two-thirds of the 0- to 2-year-old children in the population were treated with either systemic or topical antibiotics during 1 year. Physicians prescribe mostly penicillins, but the proportion of broad spectrum penicillins for young children was so high, however, that enforcement of national guidelines should be reconsidered.

Drug use in first pregnancy and lactation: a population-based survey among Danish women. The EUROMAP group

OBJECTIVE

To examine the drug prescription pattern in Danish women from 12 weeks prior to conception until 12 weeks post-partum.

METHOD

A drug utilization study based on The North Jutland Prescription Database. The Danish pharmacies use a computerized accounting system for all subsidized drugs and this was linked to the Danish Medical Birth Registry concerning prescription patterns for all women who had given birth in the county of North Jutland from 1991 to 1996.

RESULTS

The analysis included 16,001 primiparous women, who had redeemed 34,834 prescriptions prior to, during and after pregnancy. During pregnancy 44.2% of the women received prescriptions for at least one drug. Users received 2.6 prescriptions on average during pregnancy: 5% of the users redeemed 24.2% of all prescriptions. The proportion of women who redeemed prescriptions for more than three different drugs was 2.7%. The majority of prescriptions were for antibiotics (28.7%), gynaecological drugs (13.3%) and anti-asthma drugs (7.6%). The post-partum prescription proportion was 34.0% and the majority of the prescriptions during this period were for penicillins (20.1%), ophthalmologicals (15.5%) and corticosteroids for dermatological use (5.7%).

CONCLUSION

A high proportion of the women received drugs during pregnancy. The pattern of drug use within the Anatomical Therapeutical Chemical (ATC) groups changed, i.e. the amount of broad spectrum antibiotics decreased and the proportion of prescriptions for local use increased. A small proportion of women redeemed prescriptions for more than three different drugs during pregnancy.

Low use of long-term hormone replacement therapy in Denmark

AIMS

To examine individual use of hormone replacement therapy (HRT) in a defined population of Danish women during a 5-year period. HRT may reduce osteoporosis and cardiovascular disease in postmenopausal women, but may also have side-effects. Little is known about the use of HRT in most populations.

METHODS

A Pharmacoepidemiological Prescription Database was used to identify all reimbursed prescriptions for HRT in the county during the period 1991 to 1995. The Danish retail pharmacies' drug subsidy system made it possible to identify prescriptions by individual use.

RESULTS

We examined 255797 HRT prescriptions issued during the period in the County of North Jutland. Total sales reached 16.5 million defined daily doses (DDDs), purchased by 31653 women, which corresponds to 26.9% of the female population above the age of 39 years. The annual prevalence proportion of current users rose from 10.4% to 14.8% during the study period, and the therapeutic intensity (DDD/1000 women/day) increased from 20.6 to 32.0. The mean DDD sum of systemic HRT per user was 73.4 in 1991; it and the proportion of users who received less than 90 DDD per year (83.4% in 1991) remained almost constant during the study period. The amount of oestrogen unopposed by progestin was high, 28.1% of all prescriptions.

CONCLUSIONS

Less than one-fifth of the study population used HRT for more than 3 months per year, and only 32.8% of the women who were new users of HRT in 1992 continued this therapy throughout the study period.

Changes in liver-derived enzymes and self-reported alcohol consumption. A 1-year follow-up study in Denmark

BACKGROUND

The association between alcohol intake and liver disease is well known, but little is known about alcohol consumption and changes in liver-derived enzymes within 1 year. In a 1-year follow-up study we examined changes in liver-derived enzymes and their association with self-reported alcohol consumption.

METHODS

We recorded liver-derived enzyme values, self-reported alcohol consumption, and potential confounder variables at base line and at a 1-year follow-up in a representative sample of 822 persons (aged 30-50 years) from the survey of The Ebeltoft Health Promotion Project in Denmark, by using questionnaires, health examinations, and blood samples.

RESULTS

The prevalence of increased liver-derived enzyme values was 11.1% at base line and 11.8% at the 1-year follow-up. The incidence rate of increased liver-derived enzyme values was 5.1 per 100 person-years, and 34% of the cases of increased liver-derived enzyme values returned to normal within I year. We found an odds ratio of 4.0 for men and 8.0 for women of developing increased liver-derived enzyme values if alcohol consumption was more than 21 units a week. The risk seemed to be dose-dependent.

CONCLUSIONS

The prevalence of increased liver-derived enzyme values in the population was high and increased slightly during the study period. There was a strong association between the incidence rate of increased liver-derived enzyme values and self-reported alcohol consumption in a dose-dependent relationship, also when adjusted for confounding by smoking and obesity. The persons with persistently increased enzyme values had a higher weekly alcohol consumption than the rest of the study population.

Risk of acute pancreatitis in patients with chronic inflammatory bowel disease. A Danish 16-year nationwide follow-up study

BACKGROUND

There are few epidemiologic data about the risk of acute pancreatitis in chronic inflammatory bowel diseases; we therefore wanted to estimate the risk of a first episode of acute pancreatitis in patients with Crohn's disease and ulcerative colitis in the total Danish population.

METHODS

The study included all patients discharged from Danish hospitals with a diagnosis of Crohn's disease or ulcerative colitis registered in the Danish National Registry of Patients in the period from 1977 to 1992. The first episode of acute pancreatitis was identified in the cohort. The observed number of patients with acute pancreatitis was compared with expected numbers on the basis of age, sex, and calendar-specific incidence rates in the general population.

RESULTS

Overall, 15,526 patients were discharged and followed up for 112,824 person-years. The standardized incidence ratio (SIR) for acute pancreatitis was increased both in patients with Crohn's disease (SIR = 4.3; 95% confidence interval (CI), 2.9-6.1) and in those with ulcerative colitis (SIR= 2.1; 95% CI, 1.6-2.8).

CONCLUSION

Patients with chronic inflammatory bowel disease seem to be at increased risk of acute pancreatitis. Further validation and refinement of this registration-based study are needed.

Lipid-lowering medication and risk of cancer

Low or declining levels of serum cholesterol have been associated with increased mortality from cancer. We conducted a population-based cohort study of 1882 patients from one Danish county who received lipid-lowering drugs between January 1, 1991 and December 31, 1994. During the follow-up period of up to 4 years, 41 cancers were observed among users of lipid-lowering drugs, with 42.9 expected, to yield an age- and sex-standardized incidence ratio of 1.0 (95% confidence interval, 0.7-1.3). Although limited by small numbers and short follow-up period, examination by site of cancer and type of drug provided no evidence of an association. Further research is needed, however, with longer follow-up to assess more fully any potential cancer risk with these medications.

Risk of resistance related to antibiotic use before admission in patients with community-acquired bacteraemia

We analysed the association of antibiotic therapy before admission and antibiotic resistance of blood isolates in a total of 1717 community-acquired bacteraemias in the County of Northern Jutland during 1992-96. Antibiotics had been prescribed to 14% of the patients during the 30 days before admission and to 37% during the 6 months. The most frequently prescribed antibiotics within 30 days were ampicillin (28%), penicillin G (27%), sulphonamides and/or trimethoprim (16%) and macrolides (14%). The most frequent blood isolates were Escherichia coli (33%), other Enterobacteriaceae (8%), Streptococcus pneumoniae (23%) and Staphylococcus aureus (10%). Of the 575 isolates of E. coli, 425 (74%), 432 (75%) and 518 (90%) were susceptible to ampicillin, sulphonamides and trimethoprim, respectively. Previous antibiotic prescriptions were strongly associated with resistance to ampicillin, sulphonamides and trimethoprim in E. coli. The association was less pronounced for S. aureus and enteric rods other than E. coli. Antibiotic prescriptions within the last 3 months predicted antibiotic resistance, and this should be taken into account when selecting empirical antibiotic therapy of severe community-acquired infections.

Trend in incidence and case fatality of meningococcal disease over 16 years in Northern Denmark

The incidence and case fatality rates of meningococcal disease were assessed in the county of Northern Jutland, Denmark, during the 16-year period from 1980 to 1995. A total of 320 patients were identified from the Meningococcal Research Database, which comprises information from the following sources: (i) the Department of Public Health, to whom notification of meningococcal disease is obligatory; (ii) the Regional Hospital Discharge Registry; and (iii) the register of the regional department of clinical microbiology. In order to assess prognostic indicators assessable at admission, information was collected for each patient from hospital records regarding contacts, symptoms and signs on arrival, laboratory data, and course of disease. The mean incidence was 4.3 cases per 100000 persons per year (range, 2.7-7.7). The incidence increased slightly during the period studied. Overall, the case fatality rate was 9.7%, with a significant rise occurring during the period (P=0.016) and a peak occurring in 1992. Advanced age (> or = 50 years), seizures, impaired consciousness, and skin bleeding on arrival at hospital were predictors of death.

Outcome of pre-hospital antibiotic treatment of meningococcal disease

OBJECTIVE

To assess the effect of pre-hospital antibiotic treatment given by general practitioners to patients with meningococcal disease.

DESIGN

A 16-year population-based historical follow-up study based on referral letters and hospital records in the County of North Jutland, Denmark.

SUBJECTS

320 patients with meningococcal disease, of whom 302 were examined by a general practitioner before admission to hospital.

MAIN OUTCOME MEASURES

Death.

RESULTS

44 patients (14.6%) were given antibiotic treatment by the referring general practitioner. Nine of these (20.5%) died, compared with 16 (6.2%) patients who did not receive pre-hospital antibiotic treatment. The presence of skin bleeding, petechiae, and impaired consciousness were strongly associated with case fatality. Even after adjustment for these variables the odds ratio (OR) for death in patients treated with antibiotics was high (OR = 3.2; 95% CI, 0.9-10.6). In the 15 patients with skin bleeding (ecchymoses, suggillations) the case fatality rate was 100% in patients treated with antibiotics, and 50% in patients who did not receive antibiotics before hospitalization. If skin bleeding was replaced in the models by the presence of disseminated intravascular coagulation on admission, the OR for death in patients with pre-hospital antibiotic treatment was 35.9 (95% CI, 2.9-441.8) in the presence of disseminated intravascular coagulation and 1.9 (95% CI, 0.2-19.5) in its absence.

CONCLUSIONS

Pre-hospital treatment is mainly given to the most severe cases with expected high case fatality, and this confounding by indication was probably not fully adjusted for with the available data. The results contradict previous findings but provide reason to doubt the benefit of pre-hospital antibiotic treatment in patients with meningococcal disease.

The risk of a diagnosis of cancer after primary deep venous thrombosis or pulmonary embolism

BACKGROUND

Several small studies have indicated an association between deep venous thrombosis or pulmonary embolism and a subsequent diagnosis of cancer, but the subject is controversial.

METHODS

We conducted a nationwide study of a cohort of patients with deep venous thrombosis or pulmonary embolism that was drawn from the Danish National Registry of Patients for the years 1977 through 1992. The occurrence of cancer in the cohort was determined by linkage to the Danish Cancer Registry. The expected number of cancer cases was estimated on the basis of national age-, sex-, and site-specific incidence rates.

RESULTS

A total of 15,348 patients with deep venous thrombosis and 11,305 patients with pulmonary embolism were identified. We observed 1737 cases of cancer in the cohort with deep venous thrombosis, as compared with 1372 expected cases (standardized incidence ratio, 1.3; 95 percent confidence interval, 1.21 to 1.33). Among the patients with pulmonary embolism, the standardized incidence ratio was 1.3, with a 95 percent confidence interval of 1.22 to 1.41. The risk was substantially elevated only during the first six months of follow-up and declined rapidly thereafter to a constant level slightly above 1.0 one year after the thrombotic event. Forty percent of the patients given a diagnosis of cancer within one year after hospitalization for thromboembolism had distant metastases at the time of the diagnosis of cancer. There were strong associations with several cancers, most pronounced for those of the pancreas, ovary, liver (primary hepatic cancer), and brain.

CONCLUSIONS

An aggressive search for a hidden cancer in a patient with a primary deep venous thrombosis or pulmonary embolism is not warranted.

The cumulative incidence of venous thromboembolism during pregnancy and puerperium--an 11 year Danish population-based study of 63,300 pregnancies

OBJECTIVES

The aim of the study was to estimate the cumulative incidence of venous thromboembolism during pregnancy and the puerperium.

METHODS

All diagnoses concerning venous thromboembolism in the Hospital Discharge Registry from a Danish County in women less than 49 years of age from 1984 to 1994 were included. The number of deliveries in the County during this period was obtained from The Medical Registry of Birth.

RESULTS

The cumulative incidence of venous thromboembolism during pregnancy and puerperium was 0.85 (95% CI: 0.64-1.11) per 1000 deliveries. The cumulative incidence was 0.49 (95% CI: 0.28-04).80) in 1984-89 but increased to 1.23 (95% CI: 0.87-1.69) after the introduction of ultrasound.

CONCLUSION

The risk of diagnosed venous thromboembolism is low but estimates of the incidence are probably procedure dependent.

Third generation oral contraceptives and heritable thrombophilia as risk factors of non-fatal venous thromboembolism

Third generation oral contraceptives (OCs) are apparently stronger risk factors for venous thromboembolism (VTE) than other OCs, however, the increased risk may be due to confounding by indication related to differences in prescription behaviour. We estimated the risk of VTE associated with use of OCs with and without the presence of Factor V Leiden mutation, protein C-, protein S- or antithrombin deficiency. Sixty-seven cases with VTE were compared with 134 controls. The risk of VTE in the presence of thrombophilia was of the same magnitude for third generation OC users as for users of other OCs; OR: 52.5 (95% CI: 3.7-738.1) and OR: 63.3 (95% CI: 6.2-648.4), respectively. It is unlikely that confounding by indication entirely explains the risk of VTE associated with third generation OCs since the combined effect exceeds what could be explained if this source of error was the only determinant of the association.

Major haemorrhagic complications during oral anticoagulant therapy in a Danish population-based cohort

OBJECTIVES

To estimate the incidence of bleeding leading to death or hospital admission in out-patients treated with oral anticoagulants.

DESIGN

Population-based historical cohort study 1 January 1992 to 31 September 1994.

SETTING

The County of North Jutland, Denmark (488,000 inhabitants).

SUBJECTS

Six hundred and eighty-two consecutive patients commencing oral anticoagulant therapy.

MAIN OUTCOME MEASURES

Fatal bleeding or bleeding demanding hospital admission.

RESULTS

In 756 treatment-years of follow-up, there were 45 major haemorrhagic events (6.0 per 100 treatment-years) in 42 patients, of which seven (0.9 per 100 treatment-years) were fatal. The risk of a first major haemorrhagic episode was highest during the first 90 days of treatment compared with duration above one year (incidence rate ratio, IRR, 1.9; 95% CI, 0.8-4.1). The rate was highest above the age of 60 years, 6.8 per 100 treatment-years, compared with 2.9 per 100 treatment-years below 60 years (IRR 2.3; 95% CI, 1.0-5.6). The rate for a bleeding event was slightly higher in females than in males (IRR 1.3; 95% CI, 0.7-2.3), but did not vary according to type of anticoagulant drug.

CONCLUSIONS

The reported rates of major bleeding in this routine community setting implied a higher bleeding risk than was found in randomized trials or when patients are monitored in specialist anticoagulation clinics.

High prescribers of antibiotics among general practitioners--relation to prescribing habits of other drugs and use of microbiological diagnostics

General practitioners' (GPs') prescriptions of antibiotics have shown large variations and may not always be rational. We analysed GPs' prescriptions and use of microbiological diagnostics in Viborg County during a 6-month period in 1992 based on Danish Health Service data. In a logistic regression model we tried to identify potential predictors for a high prescriber of antibiotics, i.e. the GPs with the highest number of prescriptions per patient (upper quartile). Two categories were calculated for the predictor variables, dividing the distribution by the median value. The most liberal GP wrote 15 times as many prescriptions for antibiotics per patient as the most restrictive GP. A strong predictor for high prescribing of antibiotics was the number of prescriptions for other drugs per patient [odds ratio (OR) 12.3, 95% CI: 2.8-54.4] after adjustment for age and sex. High use of throat swabs was a strong negative predictor of high prescribing of antibiotics (OR 0.2, 95% CI: 0.1-0.8) while high use of cultures (OR 2.4, 95% CI: 0.8-6.9) and of urinary susceptibility tests (OR 3.1, 95% CI: 1.1-9.3) were positive predictors. The GP's general attitude to pharmacotherapy seems important for antimicrobial chemotherapy, and if use of antibiotics should be reduced, targeted strategies should be aimed at high prescribers.

[Alcohol consumption and liver enzymes in persons 30-50 years of age. Cross-sectional study from Ebeltoft]

In a representative population sample of 905 persons we examined the prevalence of raised levels of liver-derived enzymes and its possible association with self-reported alcohol consumption adjusted for smoking and BMI applying logistic regression analyses. A large proportion of 12% (women 8%; men 16%) presented raised liver-derived enzymes. Below 21 units per week (one unit equals 12 grams of alcohol) there was no association with self-reported alcohol consumption. However, the risk of abnormal liver enzymes increased with higher consumption for both sexes; if the intake was above 28 units per week, the odds ratio for raised liver enzymes increased dramatically. Whether this subclinical biochemical liver condition is an early marker of alcohol-related liver damage remains to be seen, but the long-term consequences of the reported alcohol consumption and the frequency of raised liver enzymes require follow-up.

Impact of local evidence-based clinical guidelines--a Danish intervention study

OBJECTIVE

We aimed to evaluate whether a cheap and less labour-intensive regional implementation strategy for guidelines was sufficient to change knowledge and behaviour among GPs. The model studied was the implementation of anticoagulant therapy to prevent stroke in atrial fibrillation.

METHOD

The intervention took place in the county of Viborg (149 GPs), Denmark, with the county of Ringkøbing (166 GPs) as control. A local interdisciplinary steering group modified national college-based guidelines, followed by a regional dissemination and implementation strategy. The effect of the intervention was evaluated during a follow-up period by a repeated questionnaire and by monitoring prescriptions for oral anticoagulants in 1993 and 1995 in the Danish National Health Service.

RESULTS

Adherence to the guidelines was higher after the intervention but, considering secular trends and baseline differences, the guidelines had no significant effect. The use of oral anticoagulants increased substantially in both counties during the 2-year follow-up period, but the difference in relative change between the counties was negligible. Adherence to the guidelines could not be predicted by any of the reported practice characteristics or attitudes to guidelines.

CONCLUSION

Despite solid scientific documentation and regional modification to establish ownership of nationally agreed guidelines, the impact of guidelines on GPs' knowledge and behaviour was disappointing.

Cancer risk in users of calcium channel blockers

Ca2+ channel blockers may cause cancer by inhibiting apoptosis or reducing intracellular Ca2+ in certain tissues. Recent findings suggest that drug users are at increased risk for cancer in general and for colon cancer in particular. We conducted a study in one Danish county of 17911 patients who received at least one prescription of Ca2+ channel blockers between 1 January 1991 and 31 December 1993. The patients were identified from records in the National Health Insurance Program, which refunds part of the price of such drugs. Cancer occurrence and rate were determined by use of the files of the Danish Cancer Registry and compared with county-specific incidence rates for various categories of cancer. During the follow-up period of up to 3 years, 412 cancers were observed among users of Ca2+ channel blockers, compared with 414 expected, to yield an age- and sex-standardized incidence ratio (SIR) of 1.00 (95% confidence interval, 0.90 to 1.10). There was no indication of an excess risk in the subgroup of likely long-term users or users of specific drugs. The SIR of colon cancer, a site of a priori interest, was 0.8 (95% confidence interval, 0.5 to 1.1) on the basis of 34 cases. Although the results are reassuring, the lack of association could reflect the relatively short follow-up after registration in the prescription database. Continued monitoring of cancer risk is planned.