Pieter van den Haak

Pharmo Institute for Drug Outcomes Research, Utrecht, Utrecht, Netherlands

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Publications (4)9.47 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Immunologic alterations caused by psoriasis and/or its therapies may affect the risk of serious infections. For patients with psoriasis, we explored the overall and therapy-related risk of contracting an infectious disease (ID) requiring hospitalization in a large population-based cohort. The incidence of ID was compared between patients with psoriasis and a randomly selected cohort (ratio 1:5) using hospital and pharmacy databases covering 2.5 million Dutch residents between 1997 and 2008. First and multiple IDs were defined and categorized into 20 groups based on primary International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnoses. Multivariate Cox regression and Poisson event-count models were used to test the risk difference of IDs between patients with psoriasis and reference cohort. A total of 25,742 patients with psoriasis and 128,710 reference subjects were followed up for approximately 6 years. The likelihood of IDs in patients with psoriasis was twice as high as the reference population (908 vs 438 events/100,000 person-years, crude hazard ratio 2.08, 95% confidence interval 1.96-2.22). In a multivariate model the hazard ratio decreased to 1.54 (95% confidence interval 1.44-1.65). This risk was highest for patients with more severe psoriasis (adjusted hazard ratio 1.81, 95% confidence interval 1.57-2.08), but was not associated with recent systemic antipsoriatic drug dispensing. Respiratory tract, abdominal, and skin infections occurred most frequently in patients with psoriasis. Multiple event analysis that counted the total number of infectious discharge diagnoses gave similar results. No data were available on lifestyle factors. The risk of severe infections was significantly higher for patients with psoriasis compared with control subjects and could not be explained by exposure to systemic antipsoriatic drugs.
    Journal of the American Academy of Dermatology 06/2011; 65(6):1135-44. · 4.91 Impact Factor
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    ABSTRACT: Opioid users often experience constipation. In this study the impact of constipation on QoL was assessed in patients using opioids either for non-advanced illness or advanced illness. Patients using opioids, recruited via public pharmacies, were asked to complete questionnaires on opioid use, constipation and the EuroQol five-dimension questionnaire (EQ-5D). Patients with a severe non-curable disease and relatively short life-expectancy were classified as having an advanced illness; a disabling yet not directly life-threatening condition was defined as non-advanced illness. Constipation was assessed based on questions on opioid side-effects and laxative use. EQ-5D index scores were compared between patients with and without constipation using Wilcoxon two-samples test. Questionnaires were returned by 588 patients with non-advanced illness, of whom 326 (55%) were classified as having constipation and by 113 patients with advanced illness, of whom 76 (67%) were classified as having constipation. The median EQ-5D index, a weighted health state index score with 1 = full health, was lower in patients with constipation than in patients without constipation (0.31 vs. 0.65, p< 0.01 for non-advanced illness and 0.41 vs. 0.61, p=0.12 for advanced illness). The results of this study suggest that, in patients using opioids either for non-advanced illness or advanced illness, constipation negatively influences QoL. By separately analysing patients with advanced illness and patients with non-advanced illness, possible selective non-response and confounding was accounted for, but not completely solved.
    Journal of Medical Economics 03/2010; 13(1):129-35.
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    ABSTRACT: To determine in the Netherlands what proportions of high risk patients with established cardiovascular disease (CVD) or diabetes mellitus type 2 (DM2) who were not treated with statins on 1 January 2007 and which characteristics were associated with non-treatment. From the IPCI GP database patients were selected who were registered with a GP on 1 January 2007 who had a history of either CVD (CVD patients), DM2 (diabetics) or both (diabetics with CVD). The proportion of patients using statins around 1 January 2007 was determined. Associations of patient characteristics with non-treatment were quantified (CVD patients and diabetics only). In all, 19 628 CVD patients, 5006 diabetics and 3767 diabetics with CVD were identified. Of these patients 71%, 54% and 45%, respectively did not use statins. These proportions were similar in the subgroups of patients with recent LDL-C measurements. Among these subgroups the vast majority of non-treated patients was eligible for statin treatment (LDL-C >2.5 mmol/l). The proportion of statin-treated patients was larger among diabetics than among CVD patients. Among CVD patients, female gender, age below 40 years, living in a deprived area, a history of CVD of less than 1 year and arrhythmia were significantly associated with non-treatment. Among diabetics, significant associations were: living in a deprived area and specialist visits in the previous year. In 2003, treatment rates among diabetics were lower, but among CVD patients they were similar. This suggests that the higher treatment rates among diabetics compared to CVD patients in 2007 may be the result of disease-management programmes introduced for diabetics in 2004. The majority of patients with established CVD or DM2 were not treated with statins on 1 January 2007. Eligibility for statin treatment may have been overestimated due to unavailability of cholesterol levels among many non-treated patients. Implementation of care programmes for CVD patients may increase treatment rates among eligible CVD patients.
    Current Medical Research and Opinion 11/2009; 26(2):271-8. · 2.37 Impact Factor
  • Value in Health 01/2008; 11(6). · 2.19 Impact Factor

Publication Stats

17 Citations
9.47 Total Impact Points

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Institutions

  • 2009–2011
    • Pharmo Institute for Drug Outcomes Research
      Utrecht, Utrecht, Netherlands