Risk of community-acquired pneumonia and use of gastric acid-suppressive drugs

CONTEXT

Reduction of gastric acid secretion by acid-suppressive therapy allows pathogen colonization from the upper gastrointestinal tract. The bacteria and viruses in the contaminated stomach have been identified as species from the oral cavity.

OBJECTIVE

To examine the association between the use of acid-suppressive drugs and occurrence of community-acquired pneumonia.

DESIGN, SETTING, AND PARTICIPANTS

Incident acid-suppressive drug users with at least 1 year of valid database history were identified from the Integrated Primary Care Information database between January 1, 1995, and December 31, 2002. Incidence rates for pneumonia were calculated for unexposed and exposed individuals. To reduce confounding by indication, a case-control analysis was conducted nested in a cohort of incident users of acid-suppressive drugs. Cases were all individuals with incident pneumonia during or after stopping use of acid-suppressive drugs. Up to 10 controls were matched to each case for practice, year of birth, sex, and index date. Conditional logistic regression was used to compare the risk of community-acquired pneumonia between use of proton pump inhibitors (PPIs) and H2-receptor antagonists.

MAIN OUTCOME MEASURE

Community-acquired pneumonia defined as certain (proven by radiography or sputum culture) or probable (clinical symptoms consistent with pneumonia).

RESULTS

The study population comprised 364,683 individuals who developed 5551 first occurrences of pneumonia during follow-up. The incidence rates of pneumonia in non-acid-suppressive drug users and acid-suppressive drug users were 0.6 and 2.45 per 100 person-years, respectively. The adjusted relative risk for pneumonia among persons currently using PPIs compared with those who stopped using PPIs was 1.89 (95% confidence interval, 1.36-2.62). Current users of H2-receptor antagonists had a 1.63-fold increased risk of pneumonia (95% confidence interval, 1.07-2.48) compared with those who stopped use. For current PPI users, a significant positive dose-response relationship was observed. For H2-receptor antagonist users, the variation in dose was restricted.

CONCLUSION

Current use of gastric acid-suppressive therapy was associated with an increased risk of community-acquired pneumonia.

Misclassification of exposure is high when interview data on drug use are used as a proxy measure of chronic drug use during follow-up

BACKGROUND AND OBJECTIVE

In many observational studies, the association between drugs and disease is analyzed with information from a baseline interview. We investigated the magnitude and direction of exposure misclassification by comparing interview data at baseline with prospectively gathered pharmacy data.

METHODS

The study population for this study consisted of a cohort of 2,487 participants aged 71 years or older from the Rotterdam Study. Data on drug use were gathered at the baseline interview and through pharmacies during the follow-up period between January 1, 1991, and January 1, 1999. We assessed the sensitivity, specificity, and positive and negative predictive value of interview data as proxy measures of chronic use of calcium channel blockers (CCB) in comparison with longitudinal medication records from the pharmacy.

RESULTS

Only 3 of the 206 subjects (1.5%) who reported use at baseline did not use CCBs during follow-up. Of the 2,281 persons who reported no use of CCBs at baseline, however, 354 actually used CCBs during follow-up (15.5%). The difference between interview data and pharmacy records corresponded to a misclassification bias of 0.73 (95%CI: 0.52-1.02).

CONCLUSION

Misclassification of exposure was high when interview data were used as a proxy measure of chronic use during follow-up.

HMG-CoA reductase inhibitors and the risk of vertebral fracture

Statins inhibit an enzyme in the mevalonate pathway and therefore may affect bone. In this first study on both symptomatic and nonsymptomatic vertebral fractures in the elderly (N = 3469), we show that long-term statin use is significantly associated with a 50% lower vertebral fracture risk. Randomized trials on statins and fractures, carried out in populations at risk for fractures, are needed.

INTRODUCTION

Statins are cholesterol-lowering agents that could potentially affect bone. Previous studies on statin use and fracture risk reported contradictory results and did not include both symptomatic and nonsymptomatic vertebral fractures.

MATERIALS AND METHODS

To examine the association between statin use, vertebral fractures, and lumbar spine BMD, we performed a prospective population-based cohort study in men and women (N = 3469) > or =55 years of age. These individuals had both baseline and follow-up spinal X-rays available. Statin use was obtained from detailed computerized pharmacy data, and the total number of days of exposure before second X-ray was calculated. A multivariate logistic regression model was fitted to calculate odds ratios and CIs.

RESULTS

During a mean follow-up of 6.5 years, 176 incident vertebral fractures occurred. There were 508 statin users and 16 exposed cases. The adjusted relative risk for incident vertebral fracture in users of statins (compared with nonusers) was 0.58 (95% CI, 0.34-0.99). The relative risk decreased on higher cumulative use to 0.52 (95% CI, 0.28-0.97) for use for more than 365 days during the study period. Use of (the hydrophilic statin) pravastatin and use of nonstatin cholesterol-lowering drugs was not significantly associated with vertebral fracture risk. Statin use was not significantly associated with lumbar spine BMD.

CONCLUSION

Statin use is associated with a lower risk of vertebral fracture. Randomized clinical trials in a population at risk for fracture are needed to examine this association.

Unlicensed and off-label prescription of respiratory drugs to children

Many respiratory drugs are not available in formulations suitable for infants and toddlers. Efficacy and safety research is mostly restricted to older children. However, respiratory drugs are frequently used in children for common diseases like asthma, upper and lower respiratory tract infections, rhinitis and sinusitis. The unlicensed and off-label use of respiratory drugs in children were studied. A population-based cohort study was conducted by using the computerised medical records in the Integrated Primary Care Information project. The study population comprised a random sample from all children aged 0-16 yrs who were registered with a general practitioner in 1998. All prescriptions for respiratory drugs during the study period were classified according to their licensing and off-label status. The study population comprised 13,426 patients (51.7% male, median age 8.7 yrs), of whom 2,502 (19%) received 5,253 prescriptions for respiratory drugs in 1998. A total of 3,306 (62.9%) prescriptions concerned licensed drugs. Of the remaining 1,947 prescriptions (37.1%), 882 (16.8%) were unlicensed for use in children, and 1,065 (20.3%) were prescribed off-label. The 1-yr cumulative risk of receiving an unlicensed or off-label prescription was 45% among children with at least one prescription for a respiratory drug. This population-based study showed that a large proportion of respiratory drugs prescribed by the general practitioner are unlicensed for use in children, or licensed but prescribed in an off-label manner. Results have to be interpreted with caution because they may unjustly suggest inaccurate prescribing, whereas it may be difficult to treat children with respiratory symptoms and diseases, because for many respiratory drugs paediatric data on safety and efficacy are insufficient. These findings underline the importance of research on suitable formulations, dosages and efficacy of respiratory drugs in children.

Low body mass index is associated with an increased risk of neuropsychiatric adverse events and concentration impairment in women on mefloquine

AIMS

We performed a prospective cohort study to gain more insight into risk factors for neuropsychiatric effects of mefloquine among tourists travelling to tropical areas.

METHODS

We enrolled all patients who consulted the Travel Clinic of the Havenziekenhuis & Institute for Tropical Diseases Rotterdam for mefloquine prophylaxis during the period between 1 May 1999 and 7 March 2000. Each patient was followed from baseline (prior to starting mefloquine) up to 3 weeks after starting weekly intake of 250 mg mefloquine. We compared the intraindividual change in scores between baseline and follow-up visit on the Dutch shortened Profile of Mood States, and on the Continuous Performance Test (CPT) which measures sustained attention.

RESULTS

The final cohort consisted of 151 subjects with a mean age of 38 years. In this population, a significant impairment of mood state was observed in those with a body mass index (BMI) < or = 20 kg m(-2). Stratification for gender showed that the total mood disturbance in females in the lowest BMI category significantly increased by 8.42 points [95% confidence interval (CI) 3.33, 13.50], whereas BMI did not affect the risk in males. Stratification for history of use of mefloquine showed that the risks were highest in first-time users. Analyses of the CPT showed that reaction time in women with a BMI < or = 20 kg m(-2) increased significantly by 22.5 ms (95% CI 7.80, 37.20), whereas reaction time in men showed a slight and nonsignificant decrease.

CONCLUSION

Risk factors for mefloquine-associated neuropsychiatric adverse events and concentration impairment are female gender, low BMI, and first-time use. The frequency of neuropsychiatric effects is highest in women with a BMI < or = 20 kg m(-2).

Antipsychotics and the Risk of Sudden Cardiac Death

BACKGROUND

Antipsychotics have been associated with prolongation of the corrected QT interval and sudden cardiac death. Only a few epidemiological studies have investigated this association. We performed a case-control study to investigate the association between use of antipsychotics and sudden cardiac death in a well-defined community-dwelling population.

METHODS

We performed a population-based case-control study in the Integrated Primary Care Information (IPCI) project, a longitudinal observational database with complete medical records from 150 general practitioners. All instances of death between January 1, 1995, and April 1, 2001, were reviewed. Sudden cardiac death was classified based on time between onset of cardiovascular symptoms and death. For each case, up to 10 random controls were matched for age, sex, date of sudden death, and practice. Exposure at the index date was categorized as 3 mutually exclusive groups of current use, past use, and nonuse.

RESULTS

The study population comprised 554 cases of sudden cardiac death. Current use of antipsychotics was associated with a 3-fold increase in risk of sudden cardiac death. The risk of sudden cardiac death was highest among those using butyrophenone antipsychotics, those with a defined daily dose equivalent of more than 0.5 and short-term (</=90 days) users. The association with current antipsychotic use was higher for witnessed cases (n = 334) than for unwitnessed cases.

CONCLUSIONS

Current use of antipsychotics in a general population is associated with an increased risk of sudden cardiac death, even at a low dose and for indications other than schizophrenia. Risk of sudden cardiac death was highest among recent users but remained elevated during long-term use.

No increased risk of non-Hodgkin's lymphoma with steroids, estrogens and psychotropics (Netherlands)

OBJECTIVE

Earlier studies with data on drug use from interview suggested that corticosteroids, estrogens and psychotropics may increase the risk of non-Hodgkin's lymphoma (NHL). The objective of this case-control study with complete pharmacy records was to investigate whether these results could be reproduced.

METHODS

Cases were all subjects aged 20 years and older in a population of approximately 300,000 residents in the Netherlands who were registered with an incident primary discharge diagnosis of NHL between January 1, 1991 and December 31, 1998. Controls were matched to cases on sex, year of birth, community pharmacy, calendar period and total duration of medication history. Conditional logistic regression was used to evaluate the association between categories of cumulative drug use in days and the risk of NHL.

RESULTS

997 controls were matched to 251 cases of NHL that occurred during the study period. In multivariate analyses, there was no statistically significant risk increase of NHL after exposure to corticosteroids, estrogens or psychotropics. Moreover, long-term use of benzodiazepines showed an unexpected statistically significant protective effect (OR 0.34; 95% confidence interval 0.18-0.64).

CONCLUSIONS

In our population-based study, corticosteroids, estrogens and psychotropics were not associated with an increased risk of NHL.

Underutilization of preventive strategies in patients receiving NSAIDs

BACKGROUND

Multiple treatment guidelines for non-steroidal anti-inflammatory drugs (NSAIDs) suggest that patients with one or more risk factors for NSAID-associated upper gastrointestinal (UGI) ulcer complications should be prescribed preventive strategies such as acid-suppressive drugs, misoprostol or cyclooxygenase (COX)-2-specific inhibitors to reduce their risk of serious ulcer complications. The purpose of the present study was to evaluate the extent to which new NSAID users receive recommended preventive strategies and to assess the association between risk factors and a prescription of acid suppressive drugs or misoprostol.

METHOD

A retrospective observational cohort study was conducted using the Integrated Primary Care Information (IPCI) database, a longitudinal database of electronic general practitioner patient records in The Netherlands. The study population comprised all new NSAID users, defined as users of non-specific NSAIDs, COX-2-preferential NSAIDs and COX-2-specific inhibitors, during the period from January 1996 to April 2002. Subjects were excluded if they had an H2-receptor antagonist (H2RA), proton pump inhibitor (PPI) or misoprostol prescription in the 3 months prior to the first NSAID prescription. Preventive use of acid-suppressive drugs or misoprostol was identified by the coprescription for these drugs on the same day (+/-2 days) as the NSAID prescription. The drug use for each patient was validated as having a preventive indication by reviewing the physician-recorded symptoms and diagnoses. Risk factors for UGI ulcer events were defined as age >65 yr, UGI history (gastroduodenal ulcer, UGI bleeding, dyspepsia) and concomitant medications (anticoagulants, aspirin, oral corticosteroids). The study population comprised 69 648 new NSAID users.

RESULTS

Overall, 7.9% of NSAID users received a preventive strategy (6.6% received a gastroprotective agent and an additional 1.3% received COX-2-specific inhibitors). Patients using preventive drugs had higher odds of having one or more UGI risk factors than patients without preventive drugs [adjusted odds ratio (OR) 1.78, 95% confidence interval 1.66-1.92]. Despite the greater rate of preventive drug prescriptions in patients who may have been at higher risk, 86.6% of patients with one risk factor and 81.2% with two or more risk factors received no preventive strategies. In contrast to non-specific NSAIDs, patients who received a prescription for a COX-2-specific inhibitor had significantly lower adjusted odds (OR = 0.22) of having H2RA/PPI or misoprostol coprescribed.

CONCLUSIONS

Although patients who are treated with preventive strategies have higher odds of having gastrointestinal risk factors than those not prescribed preventive therapies, the majority (>80%) of patients with one or more gastrointestinal risk factors do not receive the recommended NSAID treatment regimen of a COX-2-specific inhibitor or NSAID + H2RA/PPI or misoprostol and are therefore undertreated.

The incidence of sudden cardiac death in the general population

BACKGROUND AND OBJECTIVES

To determine the incidence of sudden cardiac death in a general (Dutch) population.

METHODS

Cohort study in the Integrated Primary Care Information (IPCI) project, a database with all medical data from 150 general practices in The Netherlands. The study population comprised 249,126 subjects with a mean follow-up of 2.54 years.

RESULTS

In this period 4,892 deaths were identified, 582 of which were classified as (probable) sudden cardiac death. The overall incidence of sudden cardiac death in this population was 0.92 cases per 1,000 person-years (95%CI: 0.85-0.99). The risk was 2.3-fold higher in men than in women, and increased with age. The incidence of sudden cardiac death peaked in October and was lowest in August.

CONCLUSIONS

The incidence of sudden cardiac death in the general Dutch population was almost 1 per 1,000 person-years per year during the period 1 January, 1995 to 1 April, 2001. Most of the cases occurred at home.

Adherence to proton pump inhibitors or H2-receptor antagonists during the use of non-steroidal anti-inflammatory drugs

BACKGROUND

The efficacy of proton pump inhibitors (PPIs) or histamine-2 receptor antagonists (H2RAs) prescribed as prophylaxis for NSAID-related upper gastrointestinal (UGI) toxicity is dependent upon patient adherence.

AIM

To describe patient adherence to prophylactically prescribed PPIs and H2RAs in the clinical setting.

METHODS

We conducted a retrospective observational cohort study using the Integrated Primary Care Information Project database. The study population consisted of incident non-specific NSAID users prescribed a PPI or H2RA specifically as prophylaxis for NSAID-related UGI toxicity. Patients were classified as non-adherent if < 75% of days of NSAID use were covered by one of these agents, and as continuing users after discontinuation of NSAID use if they had a renewed prescription for these agents after their last NSAID prescription.

RESULTS

The study cohort comprised 784 patients: 374 with H2RAs, 405 with PPIs, and 5 with both PPI and H2RA. Eighty-five percent of H2RA users and 7% of PPI users were prescribed these drugs at doses below the minimum recommended/effective dose for NSAID-associated gastroduodenal ulcer prophylaxis. Thirty-seven percent of patients were non-adherent. The lowest rate of non-adherence was associated with the first NSAID prescription (9%), increasing to 61% for patients with >/= 3 prescriptions. In a cohort of subjects who stopped their NSAID and were followed for up to 2 years (n = 711), there was significant persistent use of acid suppressive agents; 40% of patients had at least one additional prescription for the acid suppressive agent after stopping NSAIDs, and> 30% received enough drug to cover a period longer than 2 months after stopping their NSAID.

CONCLUSIONS

The pattern of PPI and H2RA prescriptions, when prescribed as prophylactic strategy, does not correspond with the pattern of NSAID use. Physicians should consider the medical impact of non-adherence with dual therapies and the impact of prolonged use of GPAs on treatment cost.

Treatment Strategies, Patterns of Drug Use and Treatment Discontinuation in Men with LUTS Suggestive of Benign Prostatic Hyperplasia: The Triumph Project

OBJECTIVES

We aimed to describe treatment strategies for lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH), adherence to and persistence with pharmacological treatment and the association between the type of LUTS/BPH complaints and early treatment discontinuation.

METHODS

Within a large GP database (IPCI) in the Netherlands we identified all males > or =45 years newly diagnosed with LUTS/BPH during 1995-2000. Details on treatment were assessed from the electronic patient records. Logistic regression analysis was used to estimate the association between the type of main urinary complaints and early treatment discontinuation.

RESULTS

Of the 2214 men with incident LUTS/BPH, 1075 received pharmacological treatment and 238 underwent prostate surgery. The average adherence differed slightly between drugs: 67% for alpha-blockers, 73% for 5alpha-reductase inhibitors and 71% for combination therapy. 26% of the treated patients discontinued treatment early. The probability of early discontinuation was higher if patients mainly expressed one type of complaint: voiding (OR(adj) 3.38; 95%CI: 1.89-6.04), post micturition (OR(adj) 2.37; 95%CI: 1.15-4.87) or storage symptoms (OR(adj) 1.85; 95%CI: 1.16-2.95) as compared to patients expressing a combination of symptoms. The risk of early discontinuation was higher if patients had a normal PSA measurement. Older age and a higher chronic disease score protected against early treatment discontinuation.

CONCLUSIONS

Almost half of newly diagnosed LUTS/BPH patients are pharmacologically treated, and a quarter discontinues very rapidly. Stopping early is more frequent among younger persons, persons with only one type of main urinary complaint, no other co-morbidity and a normal PSA.

Increased risk of achilles tendon rupture with quinolone antibacterial use, especially in elderly patients taking oral corticosteroids

BACKGROUND

In several case reports, the occurrence of Achilles tendon rupture has been attributed to the use of quinolones, but the epidemiologic evidence for this association is scanty.

METHODS

We conducted a population-based case-control study in the General Practice Research Database in the United Kingdom during the period 1988 through 1998. Cases were defined as all persons who had a first-time recording of an Achilles tendon rupture, and who had at least 18 months of valid history before the index date. As a control group, we randomly sampled 50 000 patients with at least 18 months of valid history who were assigned a random date as index date.

RESULTS

We identified 1367 cases that met the inclusion criteria. The adjusted odds ratio (OR) for Achilles tendon rupture was 4.3 (95% confidence interval [CI], 2.4-7.8) for current exposure to quinolones, 2.4 (95% CI, 1.5-3.7) for recent exposure, and 1.4 (95% CI, 0.9-2.1) for past exposure. The OR of Achilles tendon rupture was 6.4 (95% CI, 3.0-13.7) in patients aged 60 to 79 years and 20.4 (95% CI, 4.6-90.1) in patients aged 80 years or older. In persons aged 60 years and older, the OR was 28.4 (95% CI, 7.0-115.3) for current exposure to ofloxacin, while the ORs were 3.6 (95% CI, 1.4-9.1) and 14.2 (95% CI, 1.6-128.6) for ciprofloxacin and norfloxacin, respectively. Approximately 2% to 6% of all Achilles tendon ruptures in people older than 60 years can be attributed to quinolones.

CONCLUSIONS

Current exposure to quinolones increased the risk of Achilles tendon rupture. The risk is highest among elderly patients who were concomitantly treated with corticosteroids.

Nonsteroidal anti-inflammatory drugs and heart failure

Heart failure constitutes an increasing public health problem because of the growing incidence and prevalence, poor prognosis and high hospital (re)admission rates. Myocardial infarction is the underlying cause in the majority of patients, followed by hypertension, valvular heart disease and idiopathic cardiomyopathy. Nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit the enzymes cyclo-oxygenase (COX) 1 and 2, have been associated with the occurrence of symptoms of heart failure in several case reports and quantitative studies, mainly in patients with a history of cardiovascular disease or left ventricular impairment. NSAIDs may impair renal function in patients with a decreased effective circulating volume by inhibiting prostaglandin synthesis. Consequently, water and sodium retention, and decreases in renal blood flow and glomerular filtration rate may occur, affecting the unstable cardiovascular homeostasis in these patients. In patients with pre-existing heart failure, this may lead to cardiac decompensation. Putative renal-sparing NSAIDs, such as COX-2 selective inhibitors have similar effects on renal function as the traditional NSAIDs, and can likewise be expected to increase the risk of heart failure in susceptible patients. NSAIDs are frequently prescribed to elderly patients, who are particularly at risk for the renal adverse effects. If treatment with NSAIDs in high risk patients cannot be avoided, intensive monitoring and patient education is important.

Influenza vaccination in community-dwelling elderly: impact on mortality and influenza-associated morbidity

BACKGROUND

Influenza-related morbidity and mortality have been extensively studied with hospital and reimbursement data. However, little is known about the effectiveness of the annual vaccination programs in generally healthy community-dwelling elderly. The objective of our study was to investigate the effectiveness of influenza vaccination in community-dwelling elderly during the 1996 to 1997 influenza epidemic.

METHODS

We performed a population-based cohort study using the computerized Integrated Primary Care Information database in the Netherlands. Subjects who were 65 years and older in 1996 with a permanent status in a practice in the source population were considered eligible for study participation. Two cohorts were defined on the basis of vaccination status. We estimated and compared all-cause mortality, pneumonia, and clinical influenza infection rates between the cohorts.

RESULTS

Influenza vaccination was associated with a significant reduction of morbidity and mortality in vaccinated elderly (relative risk [RR], 0.72; 95% confidence interval [CI], 0.60-0.87). Influenza infections decreased significantly in the vaccinated population (RR, 0.48; 95% CI, 0.26-0.91). Mortality was reduced significantly in elderly with comorbidity (RR, 0.67; 95% CI, 0.48-0.94). The risk reduction for pneumonia was nonsignificant (RR, 0.77; 95% CI, 0.55-1.07) but was temporally related to the peak influenza activity.

CONCLUSIONS

In this study, influenza vaccination was associated with decreased mortality and influenza infections in community-dwelling elderly. Our results indicate that, in a season of mild influenza activity and good antigenic match between vaccine strains and circulating strains, influenza vaccination reduced mortality in the vaccinated population. Our data support an annual vaccination strategy for all community-dwelling elderly.

Prescription medications associated with a decreased risk of non-Hodgkin's lymphoma

Earlier epidemiologic studies have suggested an inverse association between non-Hodgkin's lymphoma and exposure to histamine(2) (H(2)) blockers, nonsteroidal anti-inflammatory drugs, cholesterol-lowering drugs, and antibiotics. Data from the PHARMO database were used to conduct a nested, population-based case-control study that included 1985-1998 drug-dispensing records for 300,000 residents of six Dutch cities. Included were those subjects without a previous history of cancer who were aged >/=20 years and were registered with an incident primary discharge diagnosis of non-Hodgkin's lymphoma between 1991 and 1998. This paper includes data on 211 cases and 800 controls individually matched on sex, age, community pharmacy, calendar time, and duration of follow-up. Conditional logistic regression analysis was used to evaluate the association between non-Hodgkin's lymphoma and categories of cumulative drug use in days. In multivariate analyses, nonsignificant risk reductions were found for all drugs tested, and the negative association tended to increase with increasing duration of use. For women, the odds ratio for H(2) blockers was 0.29 (95% confidence interval: 0.12, 0.69) and for analgesics was 0.40 (95% confidence interval: 0.22, 0.71). Results support an inverse association between occurrence of non-Hodgkin's lymphoma and use of H(2) blockers and analgesics among women, and they warrant confirmation in larger studies.

Asthma prevalence and drug prescription in asthmatic children

A cross-sectional study was conducted on among 28,856 children aged from birth to 14 years to determine the prevalence of asthma and assess its treatment in a sample of asthmatic children. Children diagnosed with asthma were identified by a sensitive algorithm applied to the information stored in the computerized medical records between 1997 and 1998. Pediatricians then reviewed and validated the diagnosis. Specific information was obtained, after age stratification under 5 yrs and over 6 ys, from the medical records and by interview regarding their personal details and treatment of asthmatic patients. In all, 1,263 cases of asthma were identified (64% males) with a prevalence of 6.3% among males and 4% among females in under 5 year-olds, and 3.9% for males and 2.1% for females in over 6 year-olds. The prevalence of asthma diagnosed directly by the pediatrician was consequently higher among under 5 year-olds, in both genders, than among the older children. Contrary to the international guidelines, pediatricians prescribed more oral corticosteroids and nebulized short-acting beta-2 agonists for children under 5 ys olds than for over 6 year-olds (13.3% Vs 4.8% and 25% Vs 10.9%, respectively, p < 0.001). For the > or = 6 year-olds, the most commonly prescribed treatments were oral antihistamines (13.9% Vs 12.6%), inhaled corticosteroids via metered-dose inhaler (30.8% Vs 28.7%) and sodium cromoglycate (12.1% Vs 4.8%, p < 0.001).

Utilisation of malaria prophylaxis: the effect of changes in guidelines in The Netherlands, 1993-1998

INTRODUCTION

The increase in international travelling from temperate zones to tropical countries and increasing drug resistance of Plasmodium falciparum has resulted in a growing number of travellers that are at risk for contracting malaria. The objective of this study was to obtain insight into dispensing patterns of malaria chemoprophylaxis and to determine whether health care providers have followed changes in guidelines.

METHODS

Data on prescriptions of proguanil and mefloquine were obtained from the Dutch 'Foundation for Pharmaceutical Statistics' (SFK) covering the period 1 January 1993 up to 31 December 1998. From Statistics Netherlands (SN), we obtained the number of travellers to endemic areas during the years 1994-1998.

RESULTS

There were 420,963 prescriptions for mefloquine and 464,904 for proguanil dispensed during the study period. The total number of prescriptions for malaria chemoprophylaxis increased during the period 1993-1997 from 98,325 (of which 14,427 (14.7%) for mefloquine and 83,898 (85.3%) for proguanil) to 168,452 (of which 90,232 (53.6%) for mefloquine and 78,220 (46.4%) for proguanil). The number of prescriptions per 1000 travellers decreased over the years for proguanil from 169 to 118 but remained stable for mefloquine at 126. The average duration for which mefloquine was prescribed remained stable, whereas the average duration for which proguanil was prescribed decreased over time. We observed differences in the prescription rate of prescriptions for mefloquine between geographical regions in the Netherlands.

CONCLUSION

Changes in the guidelines of malaria prophylaxis with respect to type and duration were generally followed by health care providers. Nevertheless there are variations between the regions in the proportion of prescribed courses of mefloquine.

Determinants for drug prescribing to children below the minimum licensed age

OBJECTIVES

In the light of the undesired effects that unlicensed and off-label drug use might have, it is necessary to study the determinants affecting the prescribing of such drugs. Prescription of drugs to children younger than the minimum licensed age may carry the highest risk of adverse reactions. To obtain insight into the factors that affect prescription of drugs to children below the minimum licensed age, we conducted a population-based case-control study.

METHODS

The case-control study was nested in a cohort of 13,426 children aged 0-16 years, who were registered in the Integrated Primary Care Information (IPCI) project, a longitudinal observational general practitioners' database in the Netherlands. "Cases" were children who received a drug prescription for which they were below the minimum licensed age. To each case we matched up to four controls based on GP practice and patient age. As potential risk factors we evaluated the use of health care resources, and acute and chronic morbidity.

RESULTS

We identified 447 cases who were matched to 1355 controls. The cases consulted their GPs significantly more often during the preceding half year, had more drug prescriptions, and had more specialist referrals than the controls. Respiratory diseases were the most important determinants for the prescription of drugs to children below the minimum licensed age. In adolescents, migraine and other headaches were the most important reasons.

CONCLUSIONS

This study showed that children suffering from respiratory disease or migraine have the highest risk of receiving a drug prescription for which the patient is below the minimum licensed age. Regulatory authorities and the pharmaceutical industry should be stimulated to improve the evaluation of drug efficacy and safety in children.

Persistent leukocyturia and loss of renal function in a prospectively monitored cohort of HIV-infected patients treated with indinavir

Symptomatic nephrotoxicity is a well-known complication of indinavir treatment. However, little is known about the relevance of other abnormalities, such as leukocyturia during use of indinavir. We determined the prevalence, risk factors, and consequences of persistent leukocyturia in a prospectively monitored cohort of indinavir users in three adult outpatient clinics. Patients were monitored for nephrotoxicity at regular visits (every 3 months) between August 1998 and September 2000. Monitoring involved urine dipstick analysis and microscopy for pH, erythrocytes, leukocytes, and indinavir crystals. The urine albumin concentration/creatinine concentration ratio and serum creatinine and indinavir plasma concentrations were measured, and urinary tract infection was excluded. Urologic symptoms were retrieved from medical records. Of 184 patients with at least one assessment, 35% had leukocyturia (i.e., >75 cells/microL) at least once during the study period, which coincided with mild increase in the serum albumin level, erythrocyturia, and crystalluria. Thirty-two (24%) of 134 patients with two or more assessments had persistent leukocyturia (i.e., on two or more occasions). Risk factors were indinavir plasma concentration of >9 mg/L, urine pH of >5.7, and crystalluria. Persistent leukocyturia was associated with a gradual loss of renal function but not with urologic symptoms. The data show that leukocyturia is a frequent finding and emphasize the need for monitoring renal function during indinavir treatment, even in the absence of urologic symptoms.

Verapamil is associated with an increased risk of cancer in the elderly: the Rotterdam study

The association between the use of calcium channel blockers (CCB) and cancer has received ample attention, but is still controversial. In this study, we have tested the hypothesis that the observed association between CCB and cancer in earlier studies could be explained by residual confounding or by misclassification of exposure because of the use of cross-sectional data on drug use. Data from the Rotterdam Study, a prospective population-based cohort study in the municipal area Ommoord, were used. The study population consisted of a cohort of 3204 participants aged 71 years or older who were followed from a baseline interview in the period 1991-1993 for the occurrence of incident cancer. Data on drug use were gathered at baseline and through the seven community pharmacies which served the Ommoord region during the study period between 1 January 1991 and 1 January 1999. Incident cancer events were gathered from a nationwide registry of hospitalisation data and from a specialised cancer centre in the Rotterdam region. We performed three analyses. First, we followed the method, and adjusted for the same risk factors, as in the earlier studies. In the second analysis, we included all risk factors that were univariately associated with cancer in the Rotterdam Study. In the third analysis, we included exposure to CCBs as time-varying co-variates, while adjusting for potential confounders. The relative risk (RR) of cancer associated with CCB was 1.4 (95% Confidence Interval (CI): 0.9-2.0) in the first analysis and lowered to 1.2 (95% CI: 0.8-1.8) upon adjustment for the different co-variates in the second. In both analyses, however, verapamil was significantly associated with cancer with RRs of 2.1 (95% CI: 1.1-4.0) and 2.0 (1.01-3.9), respectively, whereas no associations were found with the other CCB in this study, i.e. diltiazem and nifedipine. A significantly increased risk of cancer was found for intermediate daily doses of verapamil and diltiazem. Intake of other antihypertensives such as beta-blocking agents, diuretics and ACE-inhibitors was not associated with cancer. In the third analysis with exposure to CCB as time-varying co-variates, the risk increase was non-significant for use of 2 years or less, 1.0 (95% CI: 0.7-1.5), and for use for a cumulative period of more than 2 years, 1.3 (95% CI: 0.8-2.0). However, in all models the hazard ratio was statistically significantly increased for verapamil, but not for diltiazem and nifedipine. On the basis of these analyses, we found no increase in cancer in users of diltiazem and nifedipine, nor in users of other antihypertensives. In line with earlier studies, however, we found an increased risk of cancer in users of verapamil. At variance with the conclusions from several other studies, we think that it is too early to conclude that CCB are not associated with cancer.

Incidence and prevalence of lower urinary tract symptoms suggestive of benign prostatic hyperplasia in primary care--the Triumph project

OBJECTIVE

Benign prostatic hyperplasia (BPH) is one of the most common conditions associated with ageing in men. BPH often presents as lower urinary tract symptoms (LUTS) due to difficulties in voiding and irritability of the bladder. We conducted a retrospective cohort study within the Integrated Primary Care Information (IPCI) database, a general practitioners database in The Netherlands, to assess the incidence of LUTS suggestive of BPH (LUTS/BPH) in the general population.

MATERIALS

Our study population comprised all males, 45 years or older who were registered for at least 6 months prior to start of follow-up. The study period lasted from 1 January 1995 to 31 December 2000. Cases of LUTS/BPH were defined as persons with a diagnosis of BPH, treatment or surgery for BPH, or urinary symptoms suggestive of BPH that could not be explained by other co-morbidity.

RESULTS

The study cohort comprised 80,774 males who contributed 141,035 person-years of follow-up. We identified 2181 incident and 5605 prevalent LUTS/BPH cases. The overall incidence rate of LUTS/BPH was 15 per 1000 man-years (95% CI: 14.8-16.1). The incidence increased linearly (r(2) = 0.99) with age from three cases per 1000 man-years at the age of 45-49 years (95% CI: 2.4-3.6) to a maximum of 38 cases per 1000 man-years at the age of 75-79 years (95% CI: 34.1-42.9). After the age of 80 years, the incidence rate remained constant. For a symptom-free man of 46 years, the risk to develop LUTS/BPH over the coming 30 years, if he survives, is 45%. The overall prevalence of LUTS/BPH was 10.3% (95% CI: 10.2-10.5). The prevalence rate was lowest among males 45-49 years of age (2.7%) and increased with age until a maximum at the age of 80 years (24%).

CONCLUSIONS

The incidence rate of LUTS/BPH increases linearly with age and reaches its maximum at the age of 79 years.