Potential of prescription registries to capture individual-level use of aspirin and other nonsteroidal anti-inflammatory drugs in Denmark: trends in utilization 1999-2012

Nonaspirin NSAIDs and contralateral breast cancer risk

Laboratory studies suggest that inhibition of the cyclooxygenase (COX)-2 enzymes inhibits breast cancer development. We aimed to evaluate whether postdiagnosis use of COX-2 selective or other nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of contralateral breast cancer (CBC) among Danish breast cancer patients. From the clinical database of the Danish Breast Cancer Group, we identified 52,723 women diagnosed with breast cancer between 1996 and 2012. Data on nonaspirin NSAID use, CBC and potential confounding variables were obtained from nationwide registries. We defined postdiagnosis use (two or more prescriptions) as a time-varying covariate with a one-year lag. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for CBC associated with nonaspirin NSAID use. During a median follow-up of 4.8 years (interquartile range: 2.3-9 years), 1,444 patients were diagnosed with CBC. Overall, postdiagnosis use of nonaspirin NSAID was associated with an adjusted HR for CBC of 0.98 (95% CI: 0.87-1.11). The HRs did not vary substantially with duration or intensity of nonaspirin NSAID use. Moreover, similar associations were found for COX-2 selective (HR: 1.02; 95% CI: 0.85-1.23) and nonselective (HR: 0.96; 95% CI: 0.82-1.13) nonaspirin NSAIDs. In conclusion, our nationwide cohort study of breast cancer patients does not suggest a reduced risk of CBC with nonaspirin NSAID use regardless of the COX-2 selectivity.

Low-dose aspirin use and risk of contralateral breast cancer: a Danish nationwide cohort study

Observational studies of aspirin use and breast cancer risk have provided inconsistent results. The occurrence of contralateral breast cancer (CBC) among breast cancer survivors may serve as a useful high-risk model to identify preventive drug effects. Using this model, we examined the association between post-diagnosis use of low-dose aspirin and risk of CBC. We identified all women recorded with a first primary breast cancer in the Danish Breast Cancer Cooperative Group Database between 1996 and 2012. Information on drug use, tumor and patient characteristics, treatment, and CBC was obtained from nationwide registries. In the main analysis, we defined time-varying post-diagnosis low-dose aspirin use as two or more prescriptions filled during follow-up and applied a one-year exposure lag. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between post-diagnosis low-dose aspirin use and CBC risk. Among 52,723 breast cancer patients, 1,444 women developed CBC during a median follow-up of 4.8 years. The adjusted HR for CBC associated with post-diagnosis use of low-dose aspirin was 0.91 (95% CI: 0.75-1.09). We observed no substantial variation in HRs according to pattern of low-dose aspirin use or estrogen receptor status of the first or the contralateral breast cancer. In conclusion, this large nationwide cohort study of breast cancer survivors does not provide strong evidence suggesting an association between post-diagnosis use of low-dose aspirin and risk of CBC.

Non-steroidal anti-inflammatory drug use is associated with increased risk of out-of-hospital cardiac arrest: a nationwide case-time-control study

Aims

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used and have been associated with increased cardiovascular risk. Nonetheless, it remains unknown whether use of NSAIDs is associated with out-of-hospital cardiac arrest (OHCA).

Methods and results

From the nationwide Danish Cardiac Arrest Registry, all persons with OHCA during 2001-10 were identified. NSAID use 30 days before OHCA was categorized as follows: diclofenac, naproxen, ibuprofen, rofecoxib, celecoxib, and other. Risk of OHCA associated with use of NSAIDs was analysed by conditional logistic regression in case-time-control models matching four controls on sex and age per case to account for variation in drug utilization over time. We identified 28 947 persons with OHCA of whom 3376 were treated with an NSAID up to 30 days before OHCA. Ibuprofen and diclofenac were the most commonly used NSAIDs and represented 51.0% and 21.8% of total NSAID use, respectively. Use of diclofenac (odds ratio [OR], 1.50 [95% confidence interval (CI) 1.23-1.82]) and ibuprofen [OR, 1.31 (95% CI 1.14-1.51)] was associated with a significantly increased risk of OHCA. Use of naproxen [OR, 1.29 (95% CI 0.77-2.16)], celecoxib [OR, 1.13 (95% CI 0.74-1.70)], and rofecoxib (OR, 1.28 [95% CI 0.74-1.70)] was not significantly associated with increased risk of OHCA; however, these groups were characterized by few events.

Conclusion

Use of non-selective NSAIDs was associated with an increased early risk of OHCA. The result was driven by an increased risk of OHCA in ibuprofen and diclofenac users.

Diclofenac use and cardiovascular risks: series of nationwide cohort studies

OBJECTIVE

To examine the cardiovascular risks of diclofenac initiation compared with initiation of other traditional non-steroidal anti-inflammatory drugs, initiation of paracetamol, and no initiation.

DESIGN

Series of 252 nationwide cohort studies, each mimicking the strict design criteria of a clinical trial (emulated trial design).

SETTING

Danish, nationwide, population based health registries (1996-2016).

PARTICIPANTS

Individuals eligible for inclusion were all adults without malignancy; schizophrenia; dementia; or cardiovascular, kidney, liver, or ulcer diseases (that is, with low baseline risk). The study included 1 370 832 diclofenac initiators, 3 878 454 ibuprofen initiators, 291 490 naproxen initiators, 764 781 healthcare seeking paracetamol initiators matched by propensity score, and 1 303 209 healthcare seeking non-initiators also matched by propensity score.

MAIN OUTCOME MEASURES

Cox proportional hazards regression was used to compute the intention to treat hazard ratio (as a measure of the incidence rate ratio) of major adverse cardiovascular events within 30 days of initiation.

RESULTS

The adverse event rate among diclofenac initiators increased by 50% compared with non-initiators (incidence rate ratio 1.5, 95% confidence interval 1.4 to 1.7), 20% compared with paracetamol or ibuprofen initiators (both 1.2, 1.1 to 1.3), and 30% compared with naproxen initiators (1.3, 1.1 to 1.5). The event rate for diclofenac initiators increased for each component of the combined endpoint (1.2 (1.1 to 1.4) for atrial fibrillation/flutter, 1.6 (1.3 to 2.0) for ischaemic stroke, 1.7 (1.4 to 2.0) for heart failure, 1.9 (1.6 to 2.2) for myocardial infarction, and 1.7 (1.4 to 2.1) for cardiac death) as well as for low doses of diclofenac, compared with non-initiators. Although the relative risk of major adverse cardiovascular events was highest in individuals with low or moderate baseline risk (that is, diabetes mellitus), the absolute risk was highest in individuals with high baseline risk (that is, previous myocardial infarction or heart failure). Diclofenac initiation also increased the risk of upper gastrointestinal bleeding at 30 days, by approximately 4.5-fold compared with no initiation, 2.5-fold compared with initiation of ibuprofen or paracetamol, and to a similar extent as naproxen initiation.

CONCLUSIONS

Diclofenac poses a cardiovascular health risk compared with non-use, paracetamol use, and use of other traditional non-steroidal anti-inflammatory drugs.

Non-aspirin NSAID use and ovarian cancer mortality

OBJECTIVE

Preclinical studies suggest that non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) may improve survival of ovarian cancer. We examined the association between non-aspirin NSAID use and ovarian cancer mortality.

METHODS

All women in Denmark with a first diagnosis of epithelial ovarian cancer between 2000 and 2012 were identified. We obtained information on drug use, mortality outcomes, and potential confounding factors from nationwide registries. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between postdiagnosis non-aspirin NSAID use (≥1 prescription) and ovarian cancer-specific or other-cause mortality compared with non-use (no prescriptions). The influence of competing risks was evaluated using the sub-distribution hazards model proposed by Fine and Gray.

RESULTS

Among 4117 patients, any postdiagnosis use of non-aspirin NSAIDs was not associated with either ovarian cancer (HR = 0.97, 95% CI = 0.87-1.08) or other-cause (HR = 0.99, 95% CI = 0.77-1.27) mortality, however, inverse associations for ovarian cancer mortality were observed with high cumulative (HR = 0.75, 95% CI = 0.60-0.94) or high-intensity (HR = 0.86, 95% CI = 0.72-1.03) postdiagnosis use of non-aspirin NSAIDs. The associations differed substantially with histological subtype of ovarian cancer, with only inverse associations observed for serous ovarian cancer (HR = 0.87, 95% CI = 0.77-0.99). Among a smaller number of patients with a non-serous tumor, postdiagnosis non-aspirin NSAID use was associated with increased ovarian cancer mortality.

CONCLUSIONS

Any postdiagnosis use of non-aspirin NSAIDs did not influence ovarian cancer mortality overall, however, more intensive use was associated with improved survival of serous ovarian cancer.

Epidemiology of drug hypersensitivity reactions using 6-year national health insurance claim data from Korea

Background Drug hypersensitivity reactions (DHRs) constitute a large portion of adverse drug reactions (ADRs), but studies for DHR incidence based on national data are scarce. Objective This study aimed to estimate the incidence and patterns of DHRs in a Korean population and the associated utilization of medical resources using the national claims data. Setting The retrospective cohort study performed using the national insurance claim database of the Health Insurance Review and Assessment (HIRA) in Korea. Methods The International Classification of Disease 10th revision code was used to identify DHRs with 20 drug induced DHR codes. The claim data with a diagnosis of DHR in the 2009-2014 periods were analyzed. Main outcome and measure The annual incidence and the 6-year incidence rates were calculated. Incidence rate coefficients were analyzed by sex, age, and year. DHRs following with visits of emergency department (ED) or intensive care unit (ICU) were assessed for utilization of medical resources and risk of ER or ICU visits by sex and age Results A total of 535,049 patients with 1,083,507 claims were assessed in the HIRA database for 6 years. DHR incidence was high in the elderly. The risk of ED and ICU visit with DHR was also higher in the elderly than in the young [highest relative risk, RR of ED 2.59 (1.65-4.07), ICU 5.04 (2.50-10.18)]. DHRs related to blood were high in the young age. Conclusion Incidence of DHRs in the real-world clinical practice was higher in the elderly and female. Clinical consequence was more severe in the elderly.

Low-dose Aspirin, Nonsteroidal Anti-inflammatory Drugs, Selective COX-2 Inhibitors and Breast Cancer Recurrence

BACKGROUND

Aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and selective COX-2 inhibitors may improve outcomes in breast cancer patients. We investigated the association of aspirin, NSAIDs, and use of selective COX-2 inhibitors with breast cancer recurrence.

METHODS

We identified incident stage I-III Danish breast cancer patients in the Danish Breast Cancer Cooperative Group registry, who were diagnosed during 1996-2008. Prescriptions for aspirin (>99% low-dose aspirin), NSAIDs, and selective COX-2 inhibitors were ascertained from the National Prescription Registry. Follow-up began on the date of breast cancer primary surgery and continued until the first of recurrence, death, emigration, or 1 January 2013. We used Cox regression models to compute hazard ratios (HR) and corresponding 95% confidence intervals (95% CI) associating prescriptions with recurrence, adjusting for confounders.

RESULTS

We identified 34,188 breast cancer patients with 233,130 person-years of follow-up. Median follow-up was 7.1 years; 5,325 patients developed recurrent disease. Use of aspirin, NSAIDs, or selective COX-2 inhibitors was not associated with the rate of recurrence (HRadjusted aspirin = 1.0, 95% CI = 0.90, 1.1; NSAIDs = 0.99, 95% CI = 0.92, 1.1; selective COX-2 inhibitors = 1.1, 95% CI = 0.98, 1.2), relative to nonuse. Prediagnostic use of the exposure drugs was associated with reduced recurrence rates (HRaspirin = 0.92, 95% CI = 0.82, 1.0; HRNSAIDs = 0.86, 95% CI = 0.81, 0.91; HRsCOX-2inhibitors = 0.88, 95% CI = 0.83, 0.95).

CONCLUSIONS

This prospective cohort study suggests that post diagnostic prescriptions for aspirin, NSAIDs, and selective COX-2 inhibitors have little or no association with the rate of breast cancer recurrence. Prediagnostic use of the drugs was, however, associated with a reduced rate of breast cancer recurrence.

Aspirin use and ovarian cancer mortality in a Danish nationwide cohort study

BACKGROUND

Increasing data suggest that aspirin use may improve cancer survival; however, the evidence is sparse for ovarian cancer.

METHODS

We examined the association between postdiagnosis use of low-dose aspirin and mortality in a nationwide cohort of women with epithelial ovarian cancer between 2000 and 2012. Information on filled prescriptions of low-dose aspirin, dates and causes of death, and potential confounding factors was obtained from nationwide Danish registries. We used Cox regression models to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for ovarian cancer-specific or other-cause mortality associated with low-dose aspirin use.

RESULTS

Among 4117 patients, postdiagnosis use of low-dose aspirin was associated with HRs of 1.02 (95% CI: 0.87-1.20) for ovarian cancer mortality and 1.06 (95% CI: 0.77-1.47) for other-cause mortality. Hazard ratios remained neutral according to patterns of low-dose aspirin use, including prediagnosis use or established mortality predictors.

CONCLUSIONS

Low-dose aspirin use did not reduce mortality among ovarian cancer patients.

Use of prescription drugs and risk of postoperative red blood cell transfusion in breast cancer patients: a Danish population-based cohort study

BACKGROUND

Several frequently used prescription drugs may affect bleeding risk. We investigated use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), selective serotonin reuptake inhibitors (SSRIs), and statins and risk of postoperative red blood cell transfusion in breast cancer patients.

METHODS

Using Danish population-based registries, we identified a cohort of women who underwent surgery for primary breast cancer (n = 22,238) during 2005-2012 and ascertained their use of aspirin, NSAIDs, SSRIs, and statins. For each drug, patients were categorized as users if they filled ≥1 prescription in the 60 days prior to surgery. We calculated the 14-day risk of red blood cell transfusion and relative risks (RRs) with 95% confidence intervals (CIs), comparing users with nonusers for each drug and adjusting for age, cancer stage, and Charlson Comorbidity Index score.

RESULTS

In our cohort, 1385 (6.2%) women were aspirin users, 1794 (8.0%) were NSAID users, 1110 (4.9%) were SSRI users, and 2053 (9.1%) were statin users. The overall risk of red blood cell transfusion was 1.3%. The 14-day risk of RBC transfusion was 3.5% among aspirin users versus 1.1% among aspirin nonusers (adjusted RR = 1.9, 95% CI: 1.4-2.7), and 1.8% among SSRI users versus 1.2% among SSRI nonusers (adjusted RR = 1.2, 95% CI: 0.7-1.9). Red blood cell transfusion risk was increased among NSAID users, but not in a sensitivity analysis with a 30-day exposure window. Red blood cell transfusion risk was not increased among SSRI and statin users.

CONCLUSIONS

Primary breast cancer surgery confers a low risk of RBC transfusion. Still, use of aspirin and possibly NSAIDs, but not SSRIs and statins, is associated with increased red blood cell transfusion. This increased risk is not explained by differences in age, stage, or comorbidity level.

Use of oral anticoagulants in combination with antiplatelet(s) in atrial fibrillation

Objectives

To investigate temporal trends in the use of non-vitamin K oral anticoagulants (NOACs) and vitamin K antagonists (VKAs) in combination with aspirin and/or clopidogrel in patients with atrial fibrillation (AF) following acute myocardial infarction (MI) and/or percutaneous coronary intervention (PCI).

Methods

Using Danish nationwide registries, all patients with AF who survived 30 days after discharge from MI and/or PCI between 22 August 2011 and 30 September 2016 were identified.

Results

A total of 2946 patients were included in the study population, of whom 1967 (66.8%) patients were treated with VKA in combination with antiplatelet(s) (VKA+aspirin n=477, VKA+clopidogrel n=439, VKA+aspirin+clopidogrel n=1051) and 979 (33.2%) patients were treated with NOAC in combination with antiplatelet(s) (NOAC+aspirin n=252, NOAC+clopidogrel n=218, NOAC+aspirin+clopidogrel n=509). The overall study population had a median age of 76 years [IQR: 69–82] and consisted of 1995 (67.7%) men. Patients with MI as inclusion event accounted for 1613 patients (54.8%). Patients with high CHA2DS2-VASc score(congestive heart failure, hypertension, age ≥75 years (2 points), diabetes mellitus, history of stroke/transient ischemic attack/systemic thromboembolism (2 points), vascular disease, age 65-75 years, and female sex) accounted for 132 2814 (95.5%) of patients, and patients with high HAS-BLED score (hypertension, abnormal renal/liver function, history of stroke, history of bleeding, age >65 years, non-steroidal anti-inflammatory drug usages, or alcohol abuse, leaving out labile international normalized ratio (not available), and use of antiplatelets (exposure variable)) accounted for 934 (31.7%) of patients. There was an increase from 10% in 2011 to 52% in 2016 in the use of NOACs in combination with antiplatelet(s).

Conclusion

From 2011 to 2016, the use of NOAC in combination with antiplatelet(s) increased in patients with AF following MI/PCI and exceeded the use of VKA in combination with antiplatelet(s) by 2016.

No Impact of Preadmission Anti-Inflammatory Drug Use on Risk of Depression and Anxiety After Critical Illness

OBJECTIVES

Risk of depression and anxiety is elevated after intensive care. Drugs with anti-inflammatory properties may have antidepressant and anxiolytic effects. The aim of this study was to investigate the association between preadmission use of drugs with anti-inflammatory effects and risk of new-onset depression and anxiety among adult patients admitted to an ICU.

DESIGN

Propensity score-matched, population-based cohort study.

SETTING

All ICUs in Denmark from 2005 to 2013.

PATIENTS

Adults receiving mechanical ventilation in an ICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 48,207 ICU patients were included. Exposures were preadmission single-agent or combined use of statins, nonsteroidal anti-inflammatory drugs, or glucocorticoids. Outcomes were cumulative incidence (risk) and risk ratio of new-onset psychiatrist-diagnosed depression or anxiety or prescriptions for antidepressants or anxiolytics. Propensity score matching yielded 6,088 statin user pairs, 2,886 nonsteroidal anti-inflammatory drug user pairs, 1,440 glucocorticoid user pairs, and 1,743 combination drug user pairs. The cumulative incidence of anxiety and depression during the 3 years following intensive care was 18.0% (95% CI, 17.0-19.0%) for statin users, 21.3% (95% CI, 19.8-22.9%) for nonsteroidal anti-inflammatory drug users, 17.4% (95% CI, 15.4-19.5%) for glucocorticoid users, and 19.0% (95% CI, 16.3-20.2%) for combination users. The cumulative incidence was similar in nonusers compared with users in all drug groups. The risk ratio of depression and anxiety 3 years after admission to ICU was 1.04 (95% CI, 0.96-1.13) for statin users, 1.00 (95% CI, 0.90-1.11) for nonsteroidal anti-inflammatory drug users, 0.97 (95% CI, 0.82-1.14) for glucocorticoid users, and 1.05 (95% CI, 0.90-1.21) for combination users, compared with nonusers. Results were consistent across subgroups (gender, age, preadmission diseases, type of admission) and sensitivity analyses (depression and anxiety separately).

CONCLUSIONS

Preadmission use of statins, nonsteroidal anti-inflammatory drugs, glucocorticoids, or combinations did not alter the risk of depression and anxiety after critical illness.

Breast cancer recurrence after reoperation for surgical bleeding

BACKGROUND

Bleeding activates platelets that can bind tumour cells, potentially promoting metastatic growth in patients with cancer. This study investigated whether reoperation for postoperative bleeding is associated with breast cancer recurrence.

METHODS

Using the Danish Breast Cancer Group database and the Danish National Patient Register (DNPR), a cohort of women with incident stage I-III breast cancer, who underwent breast-conserving surgery or mastectomy during 1996-2008 was identified. Information on reoperation for bleeding within 14 days of the primary surgery was retrieved from the DNPR. Follow-up began 14 days after primary surgery and continued until breast cancer recurrence, death, emigration, 10 years of follow-up, or 1 January 2013. Incidence rates of breast cancer recurrence were calculated and Cox regression models were used to quantify the association between reoperation and recurrence, adjusting for potential confounders. Crude and adjusted hazard ratios according to site of recurrence were calculated.

RESULTS

Among 30 711 patients (205 926 person-years of follow-up), 767 patients had at least one reoperation within 14 days of primary surgery, and 4769 patients developed breast cancer recurrence. Median follow-up was 7·0 years. The incidence of recurrence was 24·0 (95 per cent c.i. 20·2 to 28·6) per 1000 person-years for reoperated patients and 23·1 (22·5 to 23·8) per 1000 person-years for non-reoperated patients. The overall adjusted hazard ratio was 1·06 (95 per cent c.i. 0·89 to 1·26). The estimates did not vary by site of breast cancer recurrence.

CONCLUSION

In this large cohort study, there was no evidence of an association between reoperation for bleeding and breast cancer recurrence.

Statin use and mortality among ovarian cancer patients: A population-based cohort study

Statin use has been suggested to improve prognosis in cancer patients, however, for ovarian cancer, the evidence is sparse. From the Danish Cancer Registry, we identified patients aged 30-84 years with a histologically verified first diagnosis of epithelial ovarian cancer between 2000 and 2013. Data on filled prescriptions, death, and potential confounding factors were obtained from nationwide registers. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between post-diagnostic statin use and all-cause or ovarian cancer-specific mortality. Among 4,419 patients with epithelial ovarian cancer, post-diagnostic statin use was not statistically significantly associated with all-cause (HR: 0.90, 95% CI: 0.78-1.04) or ovarian cancer-specific mortality (HR: 0.90, 95% CI: 0.76-1.08). There was little evidence of a dose-response relationship and the neutral associations persisted in sensitivity analyses. In women with endometrioid or clear cell tumour histology, cancer-specific mortality was reduced by 30-40% among statin users compared to non-users, however the analyses were limited by small numbers. Significantly reduced mortality with statin use was observed in subcohorts of new users of statins and of patients not using low-dose aspirin. In conclusion, we found no strong evidence of an association between post-diagnostic statin use and reduced mortality in ovarian cancer patients. However, our finding of potential differential susceptibility to statins among patients with different histologic types of ovarian cancer warrants further evaluation.

TP53 Arg72Pro, mortality after cancer, and all-cause mortality in 105,200 individuals

Rs1042522 (Arg72Pro) is a functional polymorphism of TP53. Pro72 has been associated with lower all-cause mortality and lower mortality after cancer. We hypothesized that TP53 Pro72 is associated with lower mortality after cancer, lower all-cause mortality, and with increased cancer incidence in the general population in a contemporary cohort. We genotyped 105,200 individuals aged 20–100 years from the Copenhagen General Population Study, recruited in 2003–2013, and followed them in Danish health registries. During follow-up 5,531 individuals died and 5,849 developed cancer. Hazard ratios for mortality after cancer were 1.03 (95% confidence interval:0.93–1.15) for Arg/Pro and 0.96 (95% CI:0.79–1.18) for Pro/Pro versus Arg/Arg. Hazard ratios for all-cause mortality were 0.99 (95% CI:0.93–1.04) for Arg/Pro and 1.09 (95% CI:0.98–1.21) for Pro/Pro versus Arg/Arg. Risk of cancer specific mortality, cardiovascular mortality, and respiratory mortality were not associated with Arg72Pro genotype overall; however, in exploratory subgroup analyses, genotype-associated risks of malignant melanoma and diabetes were altered. Considering multiple comparisons the latter findings may represent play of chance. The TP53 Arg72Pro genotype was not associated with mortality after cancer, all-cause mortality, or cancer incidence in the general population in a contemporary cohort. Our main conclusion is therefore a lack of reproducing an effect of TP53 Arg72Pro genotype on mortality.

Odense Pharmacoepidemiological Database: A Review of Use and Content

The Odense University Pharmacoepidemiological Database (OPED) is a prescription database established in 1990 by the University of Southern Denmark, covering reimbursed prescriptions from the county of Funen in Denmark and the region of Southern Denmark (1.2 million inhabitants). It is still active and thereby has more than 25 years of continuous coverage. In this MiniReview, we review its history, content, quality, coverage, governance and some of its uses. OPED's data include the Danish Civil Registration Number (CPR), which enables unambiguous linkage with virtually all other health-related registers in Denmark. Among its research uses, we review record linkage studies of drug effects, advanced drug utilization studies, some examples of method development and use of OPED as sampling frame to recruit patients for field studies or clinical trials. With the advent of other, more comprehensive sources of prescription data in Denmark, OPED may still play a role as in certain data-intensive regional studies.

Switching, Adverse Effects and Use of Over-the-Counter Analgesics among Users of Oral Anticoagulants: A Pharmacy-based Survey

Oral anticoagulants are widely used but information on important aspects in that respect is not available from medical registers or clinical databases. Therefore, we conducted a survey including patients filling a prescription for oral anticoagulants at two large Danish community pharmacies. We collected information concerning the patients' knowledge of their anticoagulant treatment including prior drug switching. Further, patients were asked about use of over-the-counter analgesics, adverse effects and how the treatment affected their everyday life. Among 335 eligible patients, 301 (90%) agreed to participate. Atrial fibrillation was the most common indication (65%), and most patients filled a prescription for a non-vitamin K antagonist oral anticoagulant (NOAC) (58%). Among the 12% (n = 35) of participants who had switched oral anticoagulant treatment, 69% had switched from a vitamin K antagonist (VKA) to a NOAC. Switching was most frequently caused by inconvenience (34%) and adverse effects (23%). Although half of all patients had recently bought over-the-counter analgesics, purchase of ibuprofen and aspirin was rare (6%). More VKA users than NOAC users felt limited in their everyday life because of anticoagulant treatment (18% versus 9%). Among non-incident NOAC users, 21% had experienced adverse effects during their current treatment. Based on first-hand information from a large sample of anticoagulant users, we conclude that the main drug-related issues leading to anticoagulant switching and perceived limitations in everyday life were inconvenience and adverse effects. This varied between drug groups. Further, use of NSAIDs obtained over the counter was rare.

Performance of the High-dimensional Propensity Score in a Nordic Healthcare Model

The high-dimensional propensity score (hdPS) is increasingly used as a tool to adjust for confounding in observational studies of drug effects. It was developed within very rich data sources, for example the American claims databases. Thus, it is unknown whether it can be applied in settings that provide little more than primary care prescriptions and diagnoses from hospital contacts, as in the Nordic data sources. Our objective was to evaluate the performance of hdPS under such circumstances. As our case, we chose the association between use of selective cyclooxygenase-2 inhibitors (coxibs) and traditional NSAIDs (tNSAIDs) and the risk of upper GI bleeding. Using Danish health registries, we identified 110,285 incident users of coxibs and 575,980 incident users of tNSAIDs and followed them for 90 days with respect to the occurrence of serious upper GI bleeding. Data were analysed using Cox regression, estimating the coxib/tNSAID hazard ratio (HR). Values below 1.00 indicate a lower estimated hazard with coxibs. We build hdPS models with inclusion of up to 500 diagnosis and 500 prescription drug covariates. The crude HR was 1.76 (95% confidence interval: 1.57-1.97), decreasing to 1.12 (1.00-1.26) and 0.99 (0.88-1.12) after adjustment for age and sex and 11 pre-selected confounders, respectively. A hdPS with inclusion of 500 most prevalent diagnoses and 500 most prevalent prescription drugs resulted in a HR of 0.89 (0.77-1.02). These estimates were consistently lower when the analysis was restricted to non-users of low-dose aspirin. The estimate based on 500 diagnoses alone was higher than an estimate based on 500 prescription drugs alone (0.99 versus 0.91). We conclude that hdPS does work within a Nordic setting that prescription data are more effective than diagnosis data in achieving confounder adjustment and that hdPS seems more effective than simple confounder adjustment by variables selected on the basis of clinical reasoning.

Efficacy of celecoxib versus ibuprofen for the treatment of patients with osteoarthritis of the knee: A randomized double-blind, non-inferiority trial

Objective

To compare the efficacy and tolerability of celecoxib and ibuprofen for the treatment of knee osteoarthritis symptoms.

Method

In this 6-week, multicentre, double-blind, non-inferiority trial, patients were randomized to 200 mg celecoxib once daily, 800 mg ibuprofen three times daily or placebo. The primary outcome was non-inferiority of celecoxib to ibuprofen in Patient’s Assessment of Arthritis Pain (scored 0–100). Secondary outcomes included the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index, Pain Satisfaction Scale, and upper gastrointestinal tolerability.

Results

A total of 388 patients were treated (celecoxib n = 153; ibuprofen n = 156; placebo n = 79). Mean difference (95% confidence interval) between celecoxib and ibuprofen in the Patient’s Assessment of Arthritis Pain was 2.76 (−3.38, 8.90). As the lower bound was greater than −10, celecoxib was non-inferior to ibuprofen. The WOMAC total score was significantly improved with celecoxib and ibuprofen, versus placebo. Patients receiving celecoxib were significantly more satisfied (versus placebo) in 10 of 11 measures on the Pain Satisfaction Scale versus three measures with ibuprofen. Upper gastrointestinal events were less frequent with celecoxib (1.3%) than ibuprofen (5.1%) or placebo (2.5%).

Conclusion

Celecoxib was well tolerated and as effective as ibuprofen for symptoms associated with knee osteoarthritis.

ClinicalTrials.gov identifier

NCT00630929

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Low-dose aspirin or other nonsteroidal anti-inflammatory drug use and prostate cancer risk: a nationwide study

PURPOSE

Increasing evidence suggests that aspirin use may protect against prostate cancer. In a nationwide case-control study, using Danish high-quality registry data, we evaluated the association between the use of low-dose aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of prostate cancer.

METHODS

We identified 35,600 patients (cases) with histologically verified prostate cancer during 2000-2012. Cases were matched to 177,992 population controls on age and residence by risk-set sampling. Aspirin and nonaspirin NSAID exposure was defined by type, estimated dose, duration, and consistency of use. We used conditional logistic regression to estimate odds ratios (ORs), with 95 % confidence intervals (CIs), for prostate cancer associated with low-dose aspirin (75-150 mg) or nonaspirin NSAID use, adjusted for potential confounders.

RESULTS

Use of low-dose aspirin was associated with an OR for prostate cancer of 0.94 (95 % CI 0.91-0.97). Slightly lower ORs were seen with increasing cumulative amount, duration, and consistency of low-dose aspirin use (continuous use, ≥5 years: OR 0.89; 95 % CI 0.82-0.97; ≥10 years: OR 0.86; 95 % CI 0.70-1.06). Nonaspirin NSAID use was associated with a slightly increased OR for prostate cancer (1.13; 95 % CI 1.10-1.15); however, this association was confined to localized disease and did not vary materially with amount, duration, or consistency of nonaspirin NSAID use.

CONCLUSIONS

Our study indicates that long-term, consistent low-dose aspirin use may provide modest protection against prostate cancer. The slightly increased risk of only localized prostate cancer with nonaspirin NSAID use suggests a noncausal explanation of the observed association.

Low-dose aspirin and rupture of abdominal aortic aneurysm

OBJECTIVE

The use of low-dose aspirin (acetylsalicylic acid [ASA]) has been suggested to attenuate growth of abdominal aortic aneurysms (AAAs), yet solid clinical evidence of this hypothesis is still missing. This study aimed to investigate whether preadmission ASA use influenced the risk of presenting with rupture of AAA (rAAA) on hospital admission and subsequent 30-day case fatality.

METHODS

There were 4010 patients with an incident diagnosis of rAAA and 4010 age- and sex-matched AAA patients identified in the Danish National Registry of Patients. Data on comorbidity, concomitant drug use, primary health care utilization, socioeconomic status, and vital status were obtained from nationwide health care and administrative registries.

RESULTS

Preadmission ASA use was identified for 1815 (45.3%) rAAA patients and 2111 (52.6%) AAA patients, corresponding to a crude odds ratio for rAAA in ASA users of 0.72 (95% confidence interval [CI], 0.66-0.79) compared with nonusers. However, after adjustment for possible confounders, no association between ASA use and the risk of rAAA was found (adjusted odds ratio, 0.97; 95% CI, 0.86-1.08). The aggregated 30-day rAAA case-fatality rate for users of ASA was 66.0% compared with 56.9% for nonusers, corresponding to an adjusted mortality rate ratio of 1.16 (95% CI, 1.06-1.27).

CONCLUSIONS

Preadmission ASA use is not associated with an altered risk of AAA rupture but seems to be associated with a worse prognosis after rupture of AAA.

Use of Antithrombotic Therapy and Long-Term Clinical Outcome Among Patients Surviving Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

The effectiveness and safety of antithrombotic therapy (AT) among patients with a history of intracerebral hemorrhage remain uncertain. We therefore determined the prevalence of indication for AT among patients hospitalized with first-time intracerebral hemorrhage and examined the impact of subsequent AT use on the long-term clinical outcome.

METHODS

We performed a population-based cohort study using nationwide Danish medical registries. Patients with risk of thromboembolism surviving the first 30 days after hospitalization because of intracerebral hemorrhage were identified and followed up. We estimated the hazard ratio of all-cause death, thromboembolic events, or major bleeding according to use of AT.

RESULTS

We identified 6369 patients between 2005 and 2013. Among these patients, 2978 (47%) had indication for AT, and during the follow-up, (median: 2.3 year) 1281 (43%) died, 497 (17%) had a thromboembolic event, and 536 (18%) had major bleeding. Postdischarge use of oral anticoagulation therapy among patients with indication for oral anticoagulation therapy was associated with a significant lower risk of death (adjusted hazard ratio, 0.59; 95% confidence interval, 0.43-0.82) and thromboembolic events (adjusted hazard ratio 0.58; 95% confidence interval, 0.35-0.97) and no increased risk of major bleeding (adjusted hazard ratio 0.65; 95% confidence interval, 0.41-1.02). In contrast, use of platelet inhibitors among patients with indication for platelet inhibitors was not related to statistically significantly improved clinical outcome.

CONCLUSIONS

Approximately 1 of 2 patients surviving intracerebral hemorrhage had a high risk of thromboembolism. Postdischarge use of oral anticoagulation therapy was associated with a lower risk of all-cause mortality and thromboembolic events and no increased risk of major bleeding.

Concomitant NSAID use during antipsychotic treatment and risk of 2-year relapse - a population-based study of 16,253 incident patients with schizophrenia

OBJECTIVE

Clinical trials have indicated antipsychotic effects of non-steroidal anti-inflammatory drugs (NSAIDs) among incident patients with schizophrenia. We aimed to study, in a population-based setting, whether concomitant use of NSAIDs or paracetamol, changed 2-year relapse risk for schizophrenia.

METHODS

We identified all incident patients with schizophrenia in Denmark diagnosed 1996-2012 initiating antipsychotic treatment within the year after diagnosis. We calculated concomitant treatment intervals for antipsychotic and NSAID or paracetamol use. Hazard rate ratios (HRR) were estimated using Cox regression adjusted for important covariates.

MAIN OUTCOME MEASURES

2-year relapse, i.e. (re)-hospitalizations with schizophrenia.

RESULTS

Among 16,235 incident patients with schizophrenia using antipsychotics, 1480 (9.1%) used NSAIDs and 767 (4.7%) paracetamol. Concomitant use of NSAIDs was associated with an increased risk of schizophrenia relapse (HRR = 1.21; 95%-CI = 1.11-1.31), particularly associated with acetylsalicylic acid and diclofenac. Concomitant use of paracetamol was not associated with schizophrenia relapse (HRR = 0.97; 95%-CI = 0.87-1.08). Subgroup analyses showed that individuals with somatic comorbidity and NSAID use had an increased relapse-risk, except for individuals with a prior hospital diagnosis for musculoskeletal disease and NSAID use who had a decreased relapse-risk (HRR = 0.82; 95%-CI = 0.71-0.94).

CONCLUSIONS

The increased relapse risk associated with concomitant NSAID use among incident patients with schizophrenia may indicate a potential impact of underlying somatic comorbidity.

Stroke and recurrent haemorrhage associated with antithrombotic treatment after gastrointestinal bleeding in patients with atrial fibrillation: nationwide cohort study

STUDY QUESTION

What are the risks of all cause mortality, thromboembolism, major bleeding, and recurrent gastrointestinal bleeding associated with restarting antithrombotic treatment after gastrointestinal bleeding in patients with atrial fibrillation?

METHODS

This Danish cohort study (1996-2012) included all patients with atrial fibrillation discharged from hospital after gastrointestinal bleeding while receiving antithrombotic treatment. Restarted treatment regimens were single or combined antithrombotic drugs with oral anticoagulation and antiplatelets. Follow-up started 90 days after discharge to avoid confounding from use of previously prescribed drugs on discharge. Risks of all cause mortality, thromboembolism, major bleeding, and recurrent gastrointestinal bleeding were estimated with competing risks models and time dependent multiple Cox regression models.

STUDY ANSWER AND LIMITATIONS

4602 patients (mean age 78 years) were included. Within two years, 39.9% (95% confidence interval 38.4% to 41.3%, n=1745) of the patients had died, 12.0% (11.0% to 13.0%, n=526) had experienced thromboembolism, 17.7% (16.5% to 18.8%, n=788) major bleeding, and 12.1% (11.1% to 13.1%, n=546) recurrent gastrointestinal bleeding. 27.1% (n=924) of patients did not resume antithrombotic treatment. Compared with non-resumption of treatment, a reduced risk of all cause mortality was found in association with restart of oral anticoagulation (hazard ratio 0.39, 95% confidence interval 0.34 to 0.46), an antiplatelet agent (0.76, 0.68 to 0.86), and oral anticoagulation plus an antiplatelet agent (0.41, 0.32 to 0.52), and a reduced risk of thromboembolism was found in association with restart of oral anticoagulation (0.41, 0.31 to 0.54), an antiplatelet agent (0.76, 0.61 to 0.95), and oral anticoagulation plus an antiplatelet agent (0.54, 0.36 to 0.82). Restarting oral anticoagulation alone was the only regimen with an increased risk of major bleeding (1.37, 1.06 to 1.77) compared with non-resumption of treatment; however, the difference in risk of recurrent gastrointestinal bleeding was not significant between patients who restarted an antithrombotic treatment regimen and those who did not resume treatment.

WHAT THIS STUDY ADDS

Among patients with atrial fibrillation who experience gastrointestinal bleeding while receiving antithrombotic treatment; subsequent restart of oral anticoagulation alone was associated with better outcomes for all cause mortality and thromboembolism compared with patients who did not resume treatment. This was despite an increased longitudinal associated risk of bleeding.

FUNDING, COMPETING INTERESTS, DATA SHARING

This study was supported by a grant from Boehringer-Ingelheim. Competing interests are available in the full paper on bmj.com. The authors have no additional data to share.

Impact of proton pump inhibitor treatment on gastrointestinal bleeding associated with non-steroidal anti-inflammatory drug use among post-myocardial infarction patients taking antithrombotics: nationwide study

STUDY QUESTION

What is the effect of proton pump inhibitors (PPIs) on the risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and treated with non-steroidal anti-inflammatory drugs (NSAIDs)?

METHODS

This was a nationwide cohort study based on linked administrative registry data from all hospitals in Denmark between 1997 and 2011. The study included patients aged 30 years and over admitted with a first myocardial infarction who survived at least 30 days after discharge. The association between PPIs and risk of gastrointestinal bleeding according to NSAID plus antithrombotic therapy was estimated using adjusted time dependent Cox regression models.

STUDY ANSWER AND LIMITATIONS

The use of PPIs was independently associated with decreased risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and treated with NSAIDs. Of 82,955 post-myocardial infarction patients (mean age 67.4 years, 64% (n=53,070) men), all of whom were taking single or dual antithrombotic therapy, 42.5% (n=35,233) filled at least one prescription for NSAIDs and 45.5% (n=37,771) received PPIs. Over a mean follow-up of 5.1 years, 3229 gastrointestinal bleeds occurred. The crude incidence rates of bleeding (events/100 person years) on NSAID plus antithrombotic therapy were 1.8 for patients taking PPIs and 2.1 for those not taking PPIs. The adjusted risk of bleeding was lower with PPI use (hazard ratio 0.72, 95% confidence interval 0.54 to 0.95) regardless of antithrombotic treatment regimen, type of NSAID, and type of PPI used. The main limitation of the study is its observational non-randomised design. The results suggest that PPI treatment probably has a beneficial effect regardless of underlying gastrointestinal risk and that when NSAIDs cannot be avoided in post-myocardial infarction patients, physicians might prescribe a PPI as well. The study does not clarify whether PPIs might be safely omitted in specific subgroups of patients with a low risk of gastrointestinal bleeding.

WHAT THIS STUDY ADDS

In post-myocardial infarction patients, bleeding complications have been associated with both antithrombotic and NSAID treatment. Concurrent use of PPIs was independently associated with a decreased risk of gastrointestinal bleeding in post-myocardial infarction patients taking antithrombotics and NSAID, regardless of antithrombotic treatment regimen, type of NSAID, and type of PPI used.

FUNDING, COMPETING INTERESTS, DATA SHARING

AMSO has received a grant from the Danish Council of Independent Research (grant 12-132760). GHG is supported by an unrestricted research scholarship from the Novo Nordisk Foundation.

Frequency of cancer in patients operated on for acute peripheral arterial thrombosis and the impact on prognosis

OBJECTIVE

Little is known about acute peripheral arterial thrombosis in patients with concomitant cancer. Small studies suggest that revascularization in this patient group is associated with thrombosis and increased risk of amputation and death. We investigated the frequency of cancer in patients operated on for acute peripheral arterial thrombosis and the long-term risk of amputation, mortality, myocardial infarction, and stroke in a national cohort.

METHODS

This was a prospective case/noncase study comprising all Danish citizens undergoing vascular surgery for acute arterial thrombosis from 1986 to 2012 with up to 26 years of follow-up.

RESULTS

A total of 7840 patients were treated surgically for acute arterial thrombosis; 2384 (30.4%) were previously diagnosed with cancer or developed cancer during the observation period. Risk of amputation was not significantly different in patients with or without cancer, except in patients with cancer diagnosed <24 months before acute limb ischemia (hazard ratio, 2.0). Mortality was significantly greater in all patients having or developing cancer within 24 months after surgery (hazard ratio, 1.2-2.2). The frequencies of myocardial infarction and stroke were similar to those among patients without cancer.

CONCLUSIONS

One of five patients operated on for acute limb ischemia has a diagnosis of cancer, and a further 3.4% will develop cancer within 24 months. The data further show that patients with acute limb ischemia and concomitant cancer can be successfully revascularized and that the majority of these patients preserve their limb. Cancer should therefore not contravene interventional treatment.

Low-Dose Aspirin or Nonsteroidal Anti-inflammatory Drug Use and Colorectal Cancer Risk: A Population-Based, Case-Control Study

BACKGROUND

A recent comprehensive review concluded that additional research is needed to determine the optimal use of aspirin for cancer prevention.

OBJECTIVE

To assess associations between the use of low-dose aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) and colorectal cancer risk.

DESIGN

Population-based, case-control study.

SETTING

Northern Denmark.

PATIENTS

Patients with first-time colorectal cancer in northern Denmark between 1994 and 2011. Population control participants were selected by risk set sampling.

MEASUREMENTS

Data on drug use, comorbid conditions, and history of colonoscopy were obtained from prescription and patient registries. Use of low-dose aspirin (75 to 150 mg) and nonaspirin NSAIDs was defined according to type, estimated dose, duration, and consistency of use.

RESULTS

Among 10 280 case patients and 102 800 control participants, the adjusted odds ratios (ORs) for colorectal cancer associated with ever use (≥2 prescriptions) of low-dose aspirin and nonaspirin NSAIDs were 1.03 (95% CI, 0.98 to 1.09) and 0.94 (CI, 0.90 to 0.98), respectively. Continuous long-term use (≥5 years) of low-dose aspirin was associated with a 27% reduction in colorectal cancer risk (OR, 0.73 [CI, 0.54 to 0.99]), whereas the overall OR for cumulative long-term use (continuous or noncontinuous) was close to unity. Nonaspirin NSAID use was associated with a substantial reduction in colorectal cancer risk, particularly for long-term, high-intensity use (average defined daily dose ≥0.3) of agents with high cyclooxygenase-2 selectivity (OR, 0.57 [CI, 0.44 to 0.74]).

LIMITATIONS

Data were unavailable on over-the-counter purchases of high-dose aspirin and low-dose ibuprofen or NSAID dosing schedules, there were several comparisons, and the authors were unable to adjust for confounding by some risk factors.

CONCLUSION

Long-term, continuous use of low-dose aspirin and long-term use of nonaspirin NSAIDs were associated with reduced colorectal cancer risk. Persons who continuously used low-dose aspirin comprised only a small proportion of the low-dose aspirin users.

PRIMARY FUNDING SOURCE

Danish Cancer Society, Aarhus University Research Foundation.

Use of nonsteroidal anti-inflammatory drugs and risk of endometrial cancer: a nationwide case-control study

PURPOSE

We examined the association between use of low-dose aspirin and non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs) and endometrial cancer risk in a nationwide case-control study.

METHODS

Cases were all women in Denmark diagnosed with endometrial cancer during 2000-2009. Age-matched female controls were randomly selected by risk-set sampling. Information on NSAID use was collected from the Prescription Registry and classified according to duration and intensity. Conditional logistic regression was used to calculate odds ratios (ORs) and 95 % confidence intervals (CIs), adjusting for potential confounders. Analyses were stratified by endometrial cancer type, and potential effect modification by parity, obesity, and hormone replacement therapy (HRT) use was investigated.

RESULTS

We identified 5,382 endometrial cancer cases and 72,127 controls. Endometrial cancer was not associated with use of low-dose aspirin (OR 0.97, 95 % CI 0.89-1.05) or non-aspirin NSAIDs (OR 0.96, 95 % CI 0.91-1.02) compared with nonuse. The ORs did not vary with increasing duration or intensity of NSAID use or with type of endometrial cancer. Interaction analyses showed reduced endometrial cancer risk associated with low-dose aspirin use among nulliparous women (OR 0.82, 95 % CI 0.70-0.95) and with non-aspirin NSAID use among women having used HRT (OR 0.90, 95 % CI 0.82-0.99).

CONCLUSIONS

We found no association between use of NSAIDs and endometrial cancer risk overall, although there were some indications of risk reductions associated with low-dose aspirin use among nulliparous women and with non-aspirin NSAID use among women having used HRT.

Limited impact of drug exposure misclassification from non-benefit thiazolidinedione drug use on mortality and hospitalizations from Saskatchewan, Canada: a cohort study

PURPOSE

Our purpose was to measure the effect of non-benefit drug use on observed associations between exposure and outcome, thereby documenting an empirical example of the potential magnitude of biases introduced when exposure status is misclassified from a restrictive drug coverage policy.

METHODS

New users of antidiabetic agents were identified with a 1-year washout period between January 1, 1995, and December 31, 2005, in Saskatchewan, Canada, and were followed until December 31, 2008. Within this population-based cohort, persons were classified as users of benefit or non-benefit thiazolidinediones (TZDs) according to their first prescription record between January 1, 2006, and December 31, 2006 (non-benefit prescription records were not captured before 2006). An intention-to-treat approach was used to categorize TZD exposure over time. We evaluated the potential bias introduced by drug exposure misclassification by evaluating bootstrapped differences in hazard ratio (HR) estimates of all-cause hospitalization or death between users and nonusers of TZDs obtained from analyses that contained complete drug use (non-benefit and benefit drug use) versus benefit drug use only (non-benefit drug use was misclassified as unexposed). All analyses were replicated within the same cohort of new users of antidiabetic agents for clopidogrel and β-blocker (bisoprolol or carvedilol) users versus nonusers because these agents were also subject to exposure misclassification from non-benefit drug use during the period of the study.

FINDINGS

Among 27,333 new users of antidiabetic agents, we identified 5759 TZD users (28% non-benefit) and 21,574 nonusers of TZDs. The crude HR for hospitalization or death among TZD users versus nonusers was higher in a database that contained benefit-only prescriptions than in a database that contained all prescriptions (HR = 1.11 [95% CI, 1.05-1.18] vs HR = 0.99 [95% CI, 0.94-1.04]). However, the differences in HRs after adjustment for demographic characteristics, health care utilization, comorbidities, and medications suggested minimal bias was introduced when TZD exposure was misclassified in the benefit-only database (adjusted HR [aHR] = 1.04 [95% CI. 0.98-1.10] vs aHR = 0.99 [95% CI, 0.94-1.04]; bootstrapped aHR difference = +0.05 [95% CI, 0.02-0.08]). Minimal differences in aHRs were also observed within analyses of clopidogrel (1551 users [24% non-benefit]; bootstrapped aHR difference = +0.01 [95% CI, -0.04 to 0.06]) and β-blocker users (351 users [42% non-benefit]; bootstrapped aHR difference = +0.06 [95% CI, -0.09 to 0.20]) versus nonusers.

IMPLICATIONS

Although patient characteristics and outcomes differed between users of non-benefit and benefit drugs, misclassification of drug exposure did not meaningfully bias estimates of all-cause mortality and hospitalization after covariate adjustment in our study.

Is the use of oral contraceptives associated with operatively treated anterior cruciate ligament injury? A case-control study from the Danish Knee Ligament Reconstruction Registry

BACKGROUND

The incidence of anterior cruciate ligament (ACL) injuries is 2 to 9 times higher in women than in men. In addition, in vitro studies have demonstrated that ACL is an estrogen target tissue, and some studies have therefore suggested a protective association between oral contraceptives (OC) and the likelihood of sustaining ACL injury.

HYPOTHESIS

There is a protective association between OC use and the likelihood of operatively treated ACL injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The study population included 4497 women with an operatively treated ACL injury registered in the Danish Knee Ligament Reconstruction Registry for the 2005 to 2011 period and 8858 age-matched controls with no ACL injury. The study evaluated exposure to OC use at the time of ACL injury (index date) and in the 5 previous years ("ever user") or no OC use ("never user"). Ever users were further classified as either new users (patients who redeemed their first prescription within the first year before the index date), long-term users (redeemed additional prescriptions 1 to 5 years before the index date), or recent users (redeemed their most recent prescription >1 year before the index date). Finally, a dose-response analysis of OC use was performed. Conditional logistic regression was used to calculate the relative risk (RR) with a 95% CI of sustaining an operatively treated ACL injury according to OC use.

RESULTS

The adjusted RR associating OC with ACL injury was 0.82 (95% CI, 0.75-0.90) between ever users and never users. Furthermore, there was a decreased RR of sustaining ACL injury of 0.80 (95% CI, 0.74-0.91) in long-term users and 0.81 (95% CI, 0.72-0.89) in recent users. Using OC for more than 4 years did not seem to alter the likelihood of sustaining an operatively treated ACL injury.

CONCLUSION

This population-based pharmacoepidemiological study including 13,355 women indicates that a protective association exists between OC use and the likelihood of sustaining an operatively treated ACL injury. Although this study does indicate a protective association of OC use, OC should not be used as a prophylactic measure before additional clinical studies have further clarified the biological and causal association between OC use and the likelihood of sustaining operatively treated ACL injury.

Peptidylarginine deiminase from Porphyromonas gingivalis contributes to infection of gingival fibroblasts and induction of prostaglandin E2 -signaling pathway

Porphyromonas gingivalis (P. gingivalis) expres-ses the enzyme peptidylarginine deiminase (PPAD), which has a strong preference for C-terminal arginines. Due to the combined activity of PPAD and Arg-specific gingipains, P. gingivalis on the cell surface is highly citrullinated. To investigate the contribution of PPAD to the interaction of P. gingivalis with primary human gingival fibroblasts (PHGF) and P. gingivalis-induced synthesis of prostaglandin E2 (PGE2 ), PHGF were infected with wild-type P. gingivalis ATCC 33277, an isogenic PPAD-knockout strain (∆ppad) or a mutated strain (C351A) expressing an inactive enzyme in which the catalytic cysteine has been mutated to alanine (PPAD(C351A) ). Cells were infected in medium containing the mutants alone or in medium supplemented with purified, active PPAD. PHGF infection was assessed by colony-forming assay, microscopic analysis and flow cytometry. Expression of cyclo-oxygenase 2 (COX-2) and microsomal PGE synthase-1 (mPGES-1), key factors in the prostaglandin synthesis pathway, was examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR), while PGE2 synthesis was evaluated by enzyme immunoassay. PHGF were infected more efficiently by wild-type P. gingivalis than by the ∆ppad strain, which correlated with strong induction of COX-2 and mPGES-1 expression by wild-type P. gingivalis, but not by the PPAD activity-null mutant strains (Δppad and C351A). The impaired ability of the Δppad strain to adhere to and/or invade PHGF and both Δppad and C351A to stimulate the PGE2 -synthesis pathway was fully restored by the addition of purified PPAD. The latter effect was strongly inhibited by aspirin. Collectively, our results implicate PPAD activity, but not PPAD itself, as an important factor for gingival fibroblast infection and activation of PGE2 synthesis, the latter of which may strongly contribute to bone resorption and eventual tooth loss.