Risk factors and short-term mortality of venous thromboembolism diagnosed in the primary care setting in the United Kingdom

BACKGROUND

Venous thromboembolism (VTE) manifesting as deep vein thrombosis (DVT) and pulmonary embolism (PE) remains a common vascular disease with high mortality and morbidity. Our aim was to study the clinical spectrum of VTE, assess its incidence in the general population, and evaluate potential risk factors.

METHODS

Prospective cohort study with nested case-control analysis using the General Practice Research Database (1994-2000). Venous thromboembolism was newly diagnosed in 6550 patients. Cases were compared with a random sample of 10,000 controls and frequency-matched by age, sex, and year.

RESULTS

The incidence rate of VTE was 74.5 per 100,000 person-years. Overweight, varicose veins, inflammatory bowel disease, cancer, and oral corticosteroid use were associated with a greater risk of VTE. Ischemic heart disease, heart failure, and cerebrovascular diseases were associated with an increased risk of PE but not with DVT. Venous thromboembolism was strongly associated with fractures (odds ratio [OR], 21.3; 95% confidence interval [CI], 15.7-28.9) and surgery (OR, 25.0; 95% CI, 14.4-43.5). In women, the risk of VTE was 1.9 (95% CI, 1.5-2.3) among those receiving opposed hormone therapy (in which the woman takes estrogen throughout the month and progesterone for 10-14 days later in the month) and 1.9 (95% CI, 1.4-2.5) among those taking oral contraceptives. Cancer and cerebrovascular diseases presented a greater relative risk of fatal PE compared with nonfatal PE.

CONCLUSIONS

Overweight, varicose veins, cancer, inflammatory bowel disease, fractures, surgery, and use of oral corticosteroids, oral contraceptives, and opposed hormone therapy were independent risk factors for both DVT and PE. The magnitude of the association with some risk factors varied between DVT and PE, as well as between fatal and nonfatal PE.

Acute and clinically relevant drug-induced liver injury: a population based case-control study

AIMS

To provide quantitative information about the absolute and relative risks of acute and clinically relevant drug-induced liver injury.

METHODS

We performed a population-based case-control study using the UK-based General Practice Research Database as the source of information. A total of 1,636,792 persons subjects aged 5-75 years old registered in the database from 1 January, 1994 to 31 December, 1999 were followed-up for a total of 5,404,705 person-years. Cases were identified by an exhaustive computer search, then reviewed manually and finally validated against the clinical records. Only idiopathic cases serious enough to be referred to hospital or a consultant were selected. A total of 5000 controls were randomly sampled from the person-time of study cohort. Current users were defined if a prescription ended within 15 days of the index date, and nonusers if there was no prescription before the index date.

RESULTS

One hundred and twenty-eight patients were considered as valid cases, being the crude incidence rate of 2.4 (95% confidence interval: 2.0, 2.8) per 100 000 person-years. The strongest associations were found with chlorpromazine (adjusted odds ratio (AOR); 95% CI = 416; 45, 3840), amoxicillin/clavulanic acid (AOR = 94.8; 27.8, 323), flucloxacillin (AOR = 17.7; 4.4, 71.0), macrolides (AOR = 6.9; 2.3, 21.0), tetracyclines (AOR = 6.2; 2.4, 15.8); metoclopramide (AOR = 6.2; 1.8, 21.3); chlorpheniramine (AOR = 9.6; 1.9, 49.7); betahistine (AOR = 15.3; 2.9, 80.7); sulphasalazine (AOR = 25.5; 6.0, 109); azathioprine (AOR = 10.5; 1.4, 76.4), diclofenac (AOR = 4.1; 1.9, 8.8) and antiepileptics (AOR = 5.1; 1.9, 13.7). A dose-effect was apparent for diclofenac, amoxicillin/clavulanic acid and flucloxacillin. The combination of two or more hepatotoxic drugs increased the risk by a factor of 6. The highest crude incidence rates were found for chlorpromazine, azathioprine, and sulfasalazine (about 1 per 1000 users).

CONCLUSIONS

Idiopathic, acute and clinically relevant liver injury, which has the use of drugs as the most probable aetiology, is a rare event in the general population. The relative risks of 40 drugs/therapeutic classes are provided, along with the crude incidence rates for 15 of them where a statistical association was found.

Incidence and risk factors for psoriasis in the general population

OBJECTIVES

To study the clinical spectrum of psoriasis and the incidence in the general population and to identify risk factors associated with the occurrence of psoriasis.

DESIGN

Prospective cohort study with nested case-control analysis.

SETTING

The data source was the United Kingdom General Practice Research Database containing computerized clinical information entered by general practitioners (GPs).

PATIENTS

The study population comprised patients receiving a first-ever diagnosis of psoriasis between January 1, 1996, and December 31, 1997, and free of cancer.

INTERVENTIONS

Diagnosis of psoriasis was validated in a random sample of 14% of all ascertained cases requesting confirmation by the GPs. Nested case-control analysis included 3994 cases of psoriasis and a random sample of 10 000 controls frequency matched to cases by age, sex, and calendar year.

MAIN OUTCOME MEASURES

Incidence rate of psoriasis and estimates of the odds ratio (OR) and 95% confidence interval (CI) for psoriasis as associated with selected risk factors.

RESULTS

The incidence rate of psoriasis was 14 per 10 000 person-years. Patients with antecedents of skin disorders and skin infection within the last year carried the highest risk of developing psoriasis (OR, 3.6 [95% CI, 3.2-4.1], and OR, 2.1 [95% CI, 1.8-2.4], respectively). Also, smoking was found to be an independent risk factors for psoriasis (OR, 1.4 [95% CI, 1.3-1.6]). We did not find an association between risk of psoriasis and antecedents of stress, diabetes, hypertension, hyperlipidemia, cardiovascular disease, or rheumatoid arthritis.

CONCLUSIONS

The incidence rate in our study was higher than those published in other studies, probably owing to our case definition that considered cases recorded by the GPs independently of a specialist confirmation. Our results confirm the association between psoriasis, skin disorders, and smoking.

Body mass, tobacco and alcohol and risk of esophageal, gastric cardia, and gastric non-cardia adenocarcinoma among men and women in a nested case-control study

OBJECTIVES

To prospectively assess the influence of body mass index (BMI), tobacco, and alcohol on the occurrence of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma, and to detect any sex differences that could explain the male predominance of these tumors.

METHODS

A case-control study nested in the General Practitioner Research Database in the United Kingdom, 1994--2001. Odds ratios (ORs) were calculated with 95% confidence intervals (CI), including multivariate analysis.

RESULTS

During follow-up of 4,340,207 person-years, we identified 287 esophageal adenocarcinomas, 195 gastric cardia adenocarcinomas, 327 gastric non-cardia adenocarcinomas, and 10,000 controls. A positive association was found between overweight (BMI > 25 kg/m(2)) and esophageal adenocarcinoma (OR 1.67, 95% CI 1.22--2.30), and gastric cardia adenocarcinoma (OR 1.46, 95% CI 0.98--2.18), but not non-cardia gastric adenocarcinoma. The association between BMI and esophageal and gastric cardia adenocarcinoma were dose-dependent and seemingly independent of reflux. No strong sex differences were identified. Smokers, particularly females, were at increased risk of all studied adenocarcinomas, while no association with alcohol was found.

CONCLUSIONS

Overweight increases risk of esophageal and gastric cardia adenocarcinoma, while tobacco smoking increases risk of esophageal, gastric cardia, and non-cardia gastric adenocarcinoma. The male predominance is not explained by sex differences in risk factor profiles of the studied exposures.

Observational data for comparative effectiveness research: an emulation of randomised trials of statins and primary prevention of coronary heart disease

This article reviews methods for comparative effectiveness research using observational data. The basic idea is using an observational study to emulate a hypothetical randomised trial by comparing initiators versus non-initiators of treatment. After adjustment for measured baseline confounders, one can then conduct the observational analogue of an intention-to-treat analysis. We also explain two approaches to conduct the analogues of per-protocol and as-treated analyses after further adjusting for measured time-varying confounding and selection bias using inverse-probability weighting. As an example, we implemented these methods to estimate the effect of statins for primary prevention of coronary heart disease (CHD) using data from electronic medical records in the UK. Despite strong confounding by indication, our approach detected a potential benefit of statin therapy. The analogue of the intention-to-treat hazard ratio (HR) of CHD was 0.89 (0.73, 1.09) for statin initiators versus non-initiators. The HR of CHD was 0.84 (0.54, 1.30) in the per-protocol analysis and 0.79 (0.41, 1.41) in the as-treated analysis for 2 years of use versus no use. In contrast, a conventional comparison of current users versus never users of statin therapy resulted in a HR of 1.31 (1.04, 1.66). We provide a flexible and annotated SAS program to implement the proposed analyses.

Risk of upper gastrointestinal complications among users of traditional NSAIDs and COXIBs in the general population

BACKGROUND & AIMS

Traditional nonaspirin, nonsteroidal anti-inflammatory drugs (tNSAIDs) have been associated with a 3- to 5-fold increased risk in upper gastrointestinal complications (UGIC). Whether use of selective inhibitors of cyclooxygenase-2 (COXIBs) will translate into a clinically relevant reduced toxicity has not been widely investigated in the general population.

METHODS

We conducted a nested case control study using The Health Improvement Network Database identifying 1561 cases of UGIC between January 2000 and 2005. A random sample of 10,000 controls was frequency matched to the cases by age, sex, and calendar year.

RESULTS

The adjusted relative risk (RR) of UGIC associated with current use was 3.7 (95% CI: 3.1-4.3) for tNSAIDs and 2.6 (95% CI: 1.9-3.6) for COXIBs. Daily dose was a predictor of increased risk for both tNSAIDs and COXIBs. Users of tNSAIDs with a prolonged plasma half-life or slow release formulations had an augmented risk of UGIC. Overall, the estimate of RR associated with COXIBs was 0.8 (95% CI: 0.6-1.1) compared with current use of tNSAIDs, and, among nonusers of aspirin, the corresponding estimate of RR associated with COXIBs was 0.6 (95% CI: 0.4-0.9).

CONCLUSIONS

COXIBs present a better upper gastrointestinal safety than tNSAIDs, although the risk of UGIC for an individual drug is determined by its daily dose and plasma drug exposure in addition to its selectivity for cyclooxygenase-2. Also, concomitant use of aspirin is a strong effect modifier of COXIBs that negates the superior gastrointestinal safety over tNSAIDs in the absence of aspirin use.

Variability among nonsteroidal antiinflammatory drugs in risk of upper gastrointestinal bleeding

OBJECTIVE

Traditional nonsteroidal antiinflammatory drugs (NSAIDs) increase the risk of upper gastrointestinal (GI) bleeding/perforation, but the magnitude of this effect for coxibs in the general population and the degree of variability between individual NSAIDs is still under debate. This study was undertaken to assess the risk of upper GI bleeding/perforation among users of individual NSAIDs and to analyze the correlation between this risk and the degree of inhibition of whole blood cyclooxygenase 1 (COX-1) and COX-2 in vitro.

METHODS

We conducted a systematic review of observational studies on NSAIDs and upper GI bleeding/perforation published between 2000 and 2008. We calculated pooled relative risk (RR) estimates of upper GI bleeding/perforation for individual NSAIDs. Additionally, we verified whether the degree of inhibition of whole blood COX-1 and COX-2 in vitro by average circulating concentrations predicted the RR of upper GI bleeding/perforation.

RESULTS

The RR of upper GI bleeding/perforation was 4.50 (95% confidence interval [95% CI] 3.82-5.31) for traditional NSAIDs and 1.88 (95% CI 0.96-3.71) for coxibs. RRs lower than that for NSAIDs overall were observed for ibuprofen (2.69 [95% CI 2.17-3.33]), rofecoxib (2.12 [95% CI 1.59-2.84]), aceclofenac (1.44 [95% CI 0.65-3.2]), and celecoxib (1.42 [95% CI 0.85-2.37]), while higher RRs were observed for ketorolac (14.54 [95% CI 5.87-36.04]) and piroxicam (9.94 [95% CI 5.99-16.50). Estimated RRs were 5.63 (95% CI 3.83-8.28) for naproxen, 5.57 (95% CI 3.94-7.87) for ketoprofen, 5.40 (95% CI 4.16-7.00) for indomethacin, 4.15 (95% CI 2.59-6.64) for meloxicam, and 3.98 (95% CI 3.36-4.72) for diclofenac. The degree of inhibition of whole blood COX-1 did not significantly correlate with RR of upper GI bleeding/perforation associated with individual NSAIDs (r(2) = 0.34, P = 0.058), but a profound and coincident inhibition (>80%) of both COX isozymes was associated with higher risk. NSAIDs with a long plasma half-life and with a slow-release formulation were associated with a greater risk than NSAIDs with a short half-life.

CONCLUSION

The results of our analysis demonstrate that risk of upper GI bleeding/perforation varies between individual NSAIDs at the doses commonly used in the general population. Drugs that have a long half-life or slow-release formulation and/or are associated with profound and coincident inhibition of both COX isozymes are associated with a greater risk of upper GI bleeding/perforation.

Antihypertensive drugs and risk of incident gout among patients with hypertension: population based case-control study

OBJECTIVE

To determine the independent associations of antihypertensive drugs with the risk of incident gout among people with hypertension.

DESIGN

Nested case-control study.

SETTING

UK general practice database, 2000-7.

PARTICIPANTS

All incident cases of gout (n = 24,768) among adults aged 20-79 and a random sample of 50,000 matched controls.

MAIN OUTCOME MEASURE

Relative risk of incident gout associated with use of antihypertensive drugs.

RESULTS

After adjusting for age, sex, body mass index, visits to the general practitioner, alcohol intake, and pertinent drugs and comorbidities, the multivariate relative risks of incident gout associated with current use of antihypertensive drugs among those with hypertension (n = 29,138) were 0.87 (95% confidence interval 0.82 to 0.93) for calcium channel blockers, 0.81 (0.70 to 0.94) for losartan, 2.36 (2.21 to 2.52) for diuretics, 1.48 (1.40 to 1.57) for β blockers, 1.24 (1.17 to 1.32) for angiotensin converting enzyme inhibitors, and 1.29 (1.16 to 1.43) for non-losartan angiotensin II receptor blockers. Similar results were obtained among those without hypertension. The multivariate relative risks for the duration of use of calcium channel blockers among those with hypertension were 1.02 for less than one year, 0.88 for 1-1.9 years, and 0.75 for two or more years and for use of losartan they were 0.98, 0.87, and 0.71, respectively (both P<0.05 for trend).

CONCLUSIONS

Compatible with their urate lowering properties, calcium channel blockers and losartan are associated with a lower risk of incident gout among people with hypertension. By contrast, diuretics, β blockers, angiotensin converting enzyme inhibitors, and non-losartan angiotensin II receptor blockers are associated with an increased risk of gout.

Non-Steroidal Antiinflammatory Drugs and the Risk of Acute Myocardial Infarction

Whether non-aspirin non-steroidal antiinflammatory drugs (NSAIDs) affect the risk of myocardial infarction is unclear. Also, it is unknown whether the effect varies by individual NSAIDs. To summarize the evidence from published observational studies on the risk of myocardial infarction associated with both traditional NSAIDs (tNSAIDs) and selective inhibitors of cyclooxygenase-2 (Coxibs), the authors conducted a systematic review of cohort and case-control studies on NSAIDs and myocardial infarction published between 2000 and 2005. Sixteen original studies were selected according to predefined criteria. Two researchers independently extracted the data on individual study characteristics and results. The authors calculated pooled relative risk (RR) estimates of myocardial infarction for specific NSAIDs compared with no NSAID use, tested the heterogeneity of effects, and evaluated potential reasons for heterogeneity. The pooled RR of myocardial infarction was 0.98 (95% confidence interval (CI): 0.92-1.05) for naproxen, 1.07 (95% CI: 1.02-1.12) for ibuprofen, 1.44 (95% CI: 1.32-1.56) for diclofenac, 0.96 (95% CI: 0.90-1.02) for celecoxib, and 1.26 (95% CI: 1.17-1.36) for rofecoxib (all doses). The pooled RR for rofecoxib at doses >25 mg/day was 1.78 (95% CI: 1.36-2.34), and 1.18 (95% CI: 1.07-1.31) for doses < or =25 mg/day. The RR associated with naproxen was 0.83 (95% CI: 0.72-0.90) among non-users of low-dose aspirin. The RR associated with rofecoxib (all doses) was 1.39 (95% CI: 1.25-1.54) among subjects without a history of myocardial infarction. The risk of myocardial infarction varies with individual NSAIDs. An increased risk was observed for diclofenac and rofecoxib, the latter one with a clear dose-response trend. There was a suggestion of a small increased risk with ibuprofen. Also, data suggest a small reduced risk for naproxen present only in non-users of aspirin, mainly people free of clinically apparent vascular disease.

Nonsteroidal antiinflammatory drugs and the risk of myocardial infarction in the general population

BACKGROUND

Nonsteroidal antiinflammatory drugs (NSAIDs) are reversible inhibitors of cyclooxygenase (COX)-1 and COX-2. Whether transient and incomplete COX-1 inhibition with NSAIDs other than aspirin will translate into clinical cardioprotection is unclear. Some reports suggest that concurrent aspirin and ibuprofen might be associated with lower cardioprotection than aspirin alone because of a pharmacodynamic interaction.

METHODS AND RESULTS

We conducted a cohort study with a nested case-control analysis. Overall, 4975 cases of acute myocardial infarction (MI) and death from coronary heart disease (CHD) were identified (January 1997 to December 2000) in the UK. A total of 20,000 controls were randomly sampled, and frequency was matched to cases by age, sex, and calendar year. The incidence rate was 5.0 per 1000 person-years. The multivariate-adjusted OR for current NSAID use compared with nonuse was 1.07 (95% CI, 0.95 to 1.20). Treatment duration or daily dose did not change the results. The effect was similar among patients free of CHD history (1.04; 95% CI, 0.90 to 1.20) and patients with previous history (1.12; 95% CI, 0.91 to 1.38). Estimates for individual NSAIDs were all comparable, with no major effect on the risk of acute MI. Naproxen was associated with an OR of 0.89 (95% CI, 0.64 to 1.24). The OR of aspirin and concurrent NSAIDs use was 1.10 (95% CI, 0.89 to 1.37) compared with aspirin alone. We observed the same result when analyzing ibuprofen and aspirin taken concomitantly.

CONCLUSIONS

This study could not demonstrate any detectable risk reduction of NSAIDs on the occurrence of MI. Our results do not support the existence of a clinically meaningful interaction between aspirin and NSAIDs, including ibuprofen.

Risk of upper gastrointestinal bleeding with low-dose acetylsalicylic acid alone and in combination with clopidogrel and other medications

BACKGROUND

This study evaluated the risk of upper gastrointestinal bleeding (UGIB) associated with use of low-dose acetylsalicylic acid (ASA) alone and in combination with other gastrotoxic medications.

METHODS AND RESULTS

The Health Improvement Network UK primary care database was used to identify individuals 40 to 84 years of age with a UGIB diagnosis in 2000 to 2007 (n = 2049). An age-, sex-, and calendar year-matched control group (n = 20,000) was identified from the same source population. The relative risk (RR) of UGIB associated with use of low-dose ASA (75 to 300 mg/d), clopidogrel, and other commonly coadministered medications was estimated by multivariate logistic regression. The risk of UGIB was increased in current users of low-dose ASA (RR, 1.80; 95% confidence interval [CI], 1.59 to 2.03) or clopidogrel (RR, 1.67; 95% CI, 1.24 to 2.24) compared with nonusers. Compared with low-dose ASA monotherapy, the risk of UGIB was significantly increased when low-dose ASA was coadministered with clopidogrel (RR, 2.08; 95% CI, 1.34 to 3.21), oral anticoagulants (RR, 2.00; 95% CI, 1.15 to 3.45), low-/medium-dose nonsteroidal antiinflammatory drugs (RR, 2.63; 95% CI, 1.93 to 3.60), high-dose nonsteroidal antiinflammatory drugs (RR, 2.66; 95% CI, 1.88 to 3.76), or high-dose oral corticosteroids (RR, 4.43; 95% CI, 2.10 to 9.34); this was not apparent with coadministration of statins (RR, 0.99; 95% CI, 0.81 to 1.21) or low-dose oral corticosteroids (RR, 1.01; 95% CI, 0.58 to 1.77).

CONCLUSIONS

Use of low-dose ASA is associated with an almost 2-fold increase in the risk of UGIB compared with nonuse. This risk is increased further in individuals taking low-dose ASA along with clopidogrel, oral anticoagulants, nonsteroidal antiinflammatory drugs, or high-dose oral corticosteroids.

Effects of non-steroidal anti-inflammatory drugs on cancer sites other than the colon and rectum: a meta-analysis

Background

Observational studies have consistently shown that aspirin and non-steroidal anti-inflammatory drug (NSAID) use is associated with a close to 50% reduced risk of colorectal cancer. Studies assessing the effects of NSAIDs on other cancers have shown conflicting results. Therefore, we conducted a meta-analysis to evaluate the relationship between NSAID use and cancer other than colorectal.

Methods

We performed a search in Medline (from 1966 to 2002) and identified a total of 47 articles (13 cohort and 34 case-control studies). Overall estimates of the relative risk (RR) were calculated for each cancer site using random effects models.

Results

Aspirin use was associated with a reduced risk of cancer of the esophagus and the stomach (RR, 0.51; 95%CI (0.38–0.69), and 0.73; 95%CI (0.63–0.84)). Use of NSAIDs was similarly associated with a lower risk of esophageal and gastric cancers (RR,0.65; 95% CI(0.46–0.92) and RR,0.54; 95%CI (0.39–0.75)). Among other cancers, only the results obtained for breast cancer were fairly consistent in showing a slight reduced risk among NSAID and aspirin users (RR, 0.77; 95%CI (0.66–0.88), and RR, 0.77; 95%CI (0.69–0.86) respectively)).

Conclusions

The results of this meta-analysis show that the potential chemopreventive role of NSAIDs in colorectal cancer might be extended to other gastrointestinal cancers such as esophagus and stomach. Further research is required to evaluate the role of NSAIDs at other cancers sites.

Bleeding Risk with Long-Term Low-Dose Aspirin: A Systematic Review of Observational Studies

BACKGROUND

Low-dose aspirin has proven effectiveness in secondary and primary prevention of cardiovascular events, but is also associated with an increased risk of major bleeding events. For primary prevention, this absolute risk must be carefully weighed against the benefits of aspirin; such assessments are currently limited by a lack of data from general populations.

METHODS

Systematic searches of Medline and Embase were conducted to identify observational studies published between 1946 and 4 March 2015 that reported the risks of gastrointestinal (GI) bleeding or intracranial hemorrhage (ICH) with long-term, low-dose aspirin (75-325 mg/day). Pooled estimates of the relative risk (RR) for bleeding events with aspirin versus non-use were calculated using random-effects models, based on reported estimates of RR (including odds ratios, hazard ratios, incidence rate ratios and standardized incidence ratios) in 39 articles.

FINDINGS

The incidence of GI bleeding with low-dose aspirin was 0.48-3.64 cases per 1000 person-years, and the overall pooled estimate of the RR with low-dose aspirin was 1.4 (95% confidence interval [CI]: 1.2-1.7). For upper and lower GI bleeding, the RRs with low-dose aspirin were 2.3 (2.0-2.6) and 1.8 (1.1-3.0), respectively. Neither aspirin dose nor duration of use had consistent effects on RRs for upper GI bleeding. The estimated RR for ICH with low-dose aspirin was 1.4 (1.2-1.7) overall. Aspirin was associated with increased bleeding risks when combined with non-steroidal anti-inflammatory drugs, clopidogrel and selective serotonin reuptake inhibitors compared with monotherapy. By contrast, concomitant use of proton pump inhibitors decreased upper GI bleeding risks relative to aspirin monotherapy.

CONCLUSIONS

The risks of major bleeding with low-dose aspirin in real-world settings are of a similar magnitude to those reported in randomized trials. These data will help inform clinical judgements regarding the use of low-dose aspirin in prevention of cardiovascular events.

Risk of upper gastrointestinal bleeding and perforation associated with low-dose aspirin as plain and enteric-coated formulations

BACKGROUND

The use of low-dose aspirin has been reported to be associated with an increased risk of upper gastrointestinal complications (UGIC). The coating of aspirin has been proposed as an approach to reduce such a risk. To test this hypothesis, we carried out a population based case-control study.

METHODS

We identified incident cases of UGIC (bleeding or perforation) aged 40 to 79 years between April 1993 to October 1998 registered in the General Practice Research Database. Controls were selected randomly from the source population. Adjusted estimates of relative risk (RR) associated with current use of aspirin as compared to non use were computed using unconditional logistic regression.

RESULTS

We identified 2,105 cases of UGIC and selected 11,500 controls. Among them, 287 (13.6%) cases and 837 (7.3%) controls were exposed to aspirin, resulting in an adjusted RR of 2.0 (1.7-2.3). No clear dose-effect was found within the range of 75-300 mg. The RR associated with enteric-coated formulations (2.3, 1.6-3.2) was similar to the one of plain aspirin (1.9, 1.6-2.3), and no difference was observed depending on the site. The first two months of treatment was the period of greater risk (RR= 4.5, 2.9-7.1). The concomitant use of aspirin with high-dose NSAIDs greatly increased the risk of UGIC (13.3, 8.5-20.9) while no interaction was apparent with low-medium doses (2.2, 1.0-4.6).

CONCLUSIONS

Low-dose aspirin increases by twofold the risk of UGIC in the general population and its coating does not modify the effect. Concomitant use of low-dose aspirin and NSAIDs at high doses put patients at a specially high risk of UGIC.

Cardioprotective aspirin users and their excess risk of upper gastrointestinal complications

BACKGROUND

To balance the cardiovascular benefits from low-dose aspirin against the gastrointestinal harm caused, studies have considered the coronary heart disease risk for each individual but not their gastrointestinal risk profile. We characterized the gastrointestinal risk profile of low-dose aspirin users in real clinical practice, and estimated the excess risk of upper gastrointestinal complications attributable to aspirin among patients with different gastrointestinal risk profiles.

METHODS

To characterize aspirin users in terms of major gastrointestinal risk factors (i.e., advanced age, male sex, prior ulcer history and use of non-steroidal anti-inflammatory drugs), we used The General Practice Research Database in the United Kingdom and the Base de Datos para la Investigación Farmacoepidemiológica en Atención Primaria in Spain. To estimate the baseline risk of upper gastrointestinal complications according to major gastrointestinal risk factors and the excess risk attributable to aspirin within levels of these factors, we used previously published meta-analyses on both absolute and relative risks of upper gastrointestinal complications.

RESULTS

Over 60% of aspirin users are above 60 years of age, 4 to 6% have a recent history of peptic ulcers and over 13% use other non-steroidal anti-inflammatory drugs. The estimated average excess risk of upper gastrointestinal complications attributable to aspirin is around 5 extra cases per 1,000 aspirin users per year. However, the excess risk varies in parallel to the underlying gastrointestinal risk and might be above 10 extra cases per 1,000 person-years in over 10% of aspirin users.

CONCLUSION

In addition to the cardiovascular risk, the underlying gastrointestinal risk factors have to be considered when balancing harms and benefits of aspirin use for an individual patient. The gastrointestinal harms may offset the cardiovascular benefits in certain groups of patients where the gastrointestinal risk is high and the cardiovascular risk is low.

Acute pancreatitis in association with type 2 diabetes and antidiabetic drugs: a population-based cohort study

OBJECTIVE

Previous observational studies have found an increased risk of acute pancreatitis among type 2 diabetic patients. However, limited information is available on this association and specifically on the role of antidiabetic treatment. Our aim, therefore, was to further assess the risk of acute pancreatitis in adult patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We performed a population-based case-control analysis nested in a cohort of 85,525 type 2 diabetic patients and 200,000 diabetes-free individuals from the general population using data from The Health Improvement Network database. Subjects were followed up to ascertain incident cases of acute pancreatitis.

RESULTS

We identified 419 cases of acute pancreatitis, 243 in the general population and 176 in the diabetes cohort. Incidence rates were 30.1 and 54.0 per 100,000 person-years in the general population and the diabetes cohort, respectively. In the cohort analysis, the adjusted incidence rate ratio of acute pancreatitis in diabetic patients versus that in the general population was 1.77 (95% CI 1.46-2.15). The magnitude of this association decreased with adjustment for multiple factors in the nested case-control analysis (adjusted odds ratio 1.37 [95% CI 0.99-1.89]). Furthermore, we found that the risk of acute pancreatitis was decreased among insulin-treated diabetic patients (0.35 [0.20-0.61]).

CONCLUSIONS

Type 2 diabetes may be associated with a slight increase in the risk of acute pancreatitis. We also found that insulin use in type 2 diabetes might decrease this risk. Further research is warranted to confirm these associations.

Nonsteroidal anti-inflammatory drugs and the incidence of Parkinson disease

Animal and epidemiologic studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of Parkinson disease (PD). The authors studied 1,258 PD cases and 6,638 controls from the General Practice Research Database. The odds ratios (95% CI) for ever vs never use were 0.93 (0.80 to 1.08) for nonaspirin NSAIDs, 1.29 (1.05 to 1.58) for aspirin, and 1.16 (1.00 to 1.35) for acetaminophen. Nonaspirin NSAID use was associated with a higher risk in women and a lower risk in men.

Discontinuation of low dose aspirin and risk of myocardial infarction: case-control study in UK primary care

OBJECTIVES

To evaluate the risk of myocardial infarction and death from coronary heart disease after discontinuation of low dose aspirin in primary care patients with a history of cardiovascular events.

DESIGN

Nested case-control study.

SETTING

The Health Improvement Network (THIN) database in the United Kingdom.

PARTICIPANTS

Individuals aged 50-84 with a first prescription for aspirin (75-300 mg/day) for secondary prevention of cardiovascular outcomes in 2000-7 (n=39,513).

MAIN OUTCOME MEASURES

Individuals were followed up for a mean of 3.2 years to identify cases of non-fatal myocardial infarction or death from coronary heart disease. A nested case-control analysis assessed the risk of these events in those who had stopped taking low dose aspirin compared with those who had continued treatment.

RESULTS

There were 876 non-fatal myocardial infarctions and 346 deaths from coronary heart disease. Compared with current users, people who had recently stopped taking aspirin had a significantly increased risk of non-fatal myocardial infarction or death from coronary heart disease combined (rate ratio 1.43, 95% confidence interval 1.12 to 1.84) and non-fatal myocardial infarction alone (1.63, 1.23 to 2.14). There was no significant association between recently stopping low dose aspirin and the risk of death from coronary heart disease (1.07, 0.67 to 1.69). For every 1000 patients, over a period of one year there were about four more cases of non-fatal myocardial infarction among patients who discontinued treatment with low dose aspirin (recent discontinuers) compared with patients who continued treatment.

CONCLUSIONS

Individuals with a history of cardiovascular events who stop taking low dose aspirin are at increased risk of non-fatal myocardial infarction compared with those who continue treatment.

Contemporary epidemiology of gout in the UK general population

Introduction

The objective of this study was to investigate the contemporary incidence of gout, examine potential risk factors, and evaluate specific gout treatment patterns in the general population.

Methods

Using the health improvement network (THIN) UK primary care database, we estimated the incidence of gout based on 24,768 newly diagnosed gout patients among a cohort of 1,775,505 individuals aged 20 to 89 years between 2000 and 2007. We evaluated potential risk factors for incident gout in a nested case-control study with 50,000 controls frequency-matched by age, sex and calendar time. We calculated odds ratios (OR) by means of unconditional logistic regression adjusting for demographic variables, lifestyle variables, relevant medical conditions and drug exposures.

Results

The incidence of gout per 1,000 person-years was 2.68 (4.42 in men and 1.32 in women) and increased with age. Conventional risk factors were significantly and strongly associated with the risk of gout, with multivariate ORs of 3.00 (95% confidence interval (CI)) for excessive alcohol intake (that is, more than 42 units per week), 2.34 (95% CI 2.22 to 2.47) for obesity (body mass index > = 30 kg/m²), 2.48 (95% CI 2.19 to 2.81) for chronic renal impairment, and 3.00 (95% CI 2.85 to 3.15) for current diuretic use. For other medical conditions the multivariate OR were 1.84 (95% CI 1.70 to 2.00) for heart failure, 1.45 (95% CI 1.18 to 1.79) for hypertriglyceridemia and 1.12 (95% CI 1.04 to 1.22) for psoriasis. Use of cyclosporine was associated with an OR of 3.72 (95% CI, 2.17 to 6.40). Among gout-specific therapies, allopurinol was the most frequently used with a one-year cumulative incidence of 28% in a cohort of incident gout diagnosed from 2000 to 2001. Use of gout-specific treatment has not changed over recent years except for an increase of colchicine.

Conclusions

The contemporary incidence of gout in UK remains substantial. In this general population cohort, associations with previously purported risk factors were evident including psoriasis, heart failure, hypertriglyceridemia, and cyclosporine therapy. Use of gout-specific treatment has remained relatively constant in recent years except for an increase of colchicine.

Morbidity associated with sleep disorders in primary care: a longitudinal cohort study

OBJECTIVE

Few epidemiologic studies evaluate the relative contribution of different risk factors on sleep problems. The aim of the present study was to assess demographics, comorbid characteristics, and health outcomes in patients with sleep disorders.

METHOD

A population-based cohort study with nested case-control analysis was conducted in adults using the U.K. General Practice Research Database. Information was collected for 12,437 patients with a new sleep disorder diagnosis during the year 1996 and 18,350 age- and sex-matched controls. Logistic regression analysis was used to compute odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

The incidence of a new sleep disorder diagnosis was 12.5 per 1000 person-years. There was a clear association of sleep disorders with smoking and excessive alcohol consumption; prior psychiatric disorders, including stress (OR = 3.6, 95% CI = 2.9 to 4.4) and depression (OR = 3.1, 95% CI = 2.8 to 3.3); prior circulatory diseases, including heart failure (OR = 1.8, 95% CI = 1.4 to 2.2) and coronary heart disease (OR = 1.4, 95% CI = 1.2 to 1.6); and prior gastrointestinal diseases, including gastroesopha-geal reflux disease (OR = 1.4, 95% CI = 1.2 to 1.7) and irritable bowel syndrome (OR = 1.5, 95% CI = 1.2 to 1.9). Use of hypnotics and anti-depressants was increased in the year after diagnosis. Relative 1-year mortality risk was 3-fold higher in the sleep disorder group than in controls, with a noticeably higher proportion of deaths due to suicide.

CONCLUSION

The fact that sleep disorders were associated with several morbidities, most strongly with psychiatric disorders as well as with increased mortality, underscores the importance of sleep problems as indicators of health status.

Impact of diabetes against the future risk of developing gout

OBJECTIVE

Although hyperuricaemia and gout are associated with an increased future risk of diabetes, diabetes may reduce the future risk of gout through the uricosuric effect of glycosuria or the impaired inflammatory response. The present work evaluates the impact of diabetes on the future risk of developing gout.

METHODS

A case-control study nested in a UK general practice database (the health improvement network) was conducted by identifying all incident cases of gout (N=24 768) and randomly sampling 50,000 controls who were 20-89 years between 2000 and 2007. The independent effect of type 1 and type 2 diabetes on the development of incident gout was examined.

RESULTS

After adjusting for age, sex, body mass index, general practitioner visits, smoking, alcohol intake, ischaemic heart disease and presence of cardiovascular risk factors, the RR for incident gout among patients with diabetes, as compared with individuals with no diabetes was 0.67 (95% CI 0.63 to 0.71). The multivariate RRs with the duration of diabetes of 0-3, 4-9 and ≥ 10 years were 0.81 (95% CI 0.74 to 0.90), 0.67 (95% CI 0.61 to 0.73) and 0.52 (95% CI 0.46 to 0.58), respectively. The inverse association was stronger with type 1 diabetes than with type 2 diabetes (multivariate RR, 0.33 vs 0.69) and stronger among men than women (p value for interaction < 0.001).

CONCLUSIONS

Individuals with diabetes are at a lower future risk of gout independent of other risk factors. These data provide support for a substantial role of the pathophysiology associated with diabetes against the risk of developing gout.

Acid suppressants reduce risk of gastrointestinal bleeding in patients on antithrombotic or anti-inflammatory therapy

BACKGROUND & AIMS

We investigated the effect of different prevention strategies against upper gastrointestinal bleeding (UGIB) in the general population and in patients on antithrombotic or anti-inflammatory treatments.

METHODS

We performed a population-based, nested, case-control study using The Health Improvement Network UK primary care database. From 2000 to 2007, we identified 2049 cases of UGIB and 20,000 controls. The relative risk (RR) of UGIB associated with various gastroprotective agents was estimated by comparing current use (defined as use within 30 days of the index date) with nonuse in the previous year, using multivariate logistic regression.

RESULTS

The adjusted RR of UGIB associated with current use of proton pump inhibitors (PPIs) for more than 1 month was 0.58 (95% confidence interval [CI], 0.42-0.79) among patients who received low-dose acetylsalicylic acid (ASA), 0.18 (95% CI, 0.04-0.79) for clopidogrel, 0.17 (95% CI, 0.04-0.76) for dual antiplatelet therapy, 0.48 (95% CI, 0.22-1.04) for warfarin, and 0.51 (95% CI, 0.34-0.78) for nonsteroidal anti-inflammatory drugs. The corresponding estimates for therapy with histamine-2-receptor antagonists (H2RAs) were more unstable, but tended to be of a smaller magnitude. In the general population, PPI use was associated with a reduced risk of UGIB compared with nonuse (RR, 0.80; 95% CI, 0.68-0.94); no such reduction was observed for H2RAs or nitrates.

CONCLUSIONS

PPI use was associated with a lower risk of UGIB in the general population and in patients on antithrombotic or anti-inflammatory therapy compared with nonuse of PPIs. The reduction in risks of UGIB was smaller in H2RA than in PPI users.

Confounding adjustment via a semi-automated high-dimensional propensity score algorithm: an application to electronic medical records

PURPOSE

A semi-automated high-dimensional propensity score (hd-PS) algorithm has been proposed to adjust for confounding in claims databases. The feasibility of using this algorithm in other types of healthcare databases is unknown.

METHODS

We estimated the comparative safety of traditional non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors regarding the risk of upper gastrointestinal bleeding (UGIB) in The Health Improvement Network, an electronic medical record (EMR) database in the UK. We compared the adjusted effect estimates when the confounders were identified using expert knowledge or the semi-automated hd-PS algorithm.

RESULTS

Compared with the 411,616 traditional NSAID initiators, the crude odds ratio (OR) of UGIB was 1.50 (95%CI: 0.98, 2.28) for the 43,569 selective COX-2 inhibitor initiators. The OR dropped to 0.81 (0.52, 1.27) upon adjustment for known risk factors for UGIB that are typically available in both claims and EMR databases. The OR remained similar when further adjusting for covariates--smoking, alcohol consumption, and body mass index-that are not typically recorded in claims databases (OR 0.81; 0.51, 1.26) or adding 500 empirically identified covariates using the hd-PS algorithm (OR 0.78; 0.49, 1.22). Adjusting for age and sex plus 500 empirically identified covariates produced an OR of 0.87 (0.56, 1.34).

CONCLUSIONS

The hd-PS algorithm can be implemented in pharmacoepidemiologic studies that use primary care EMR databases such as The Health Improvement Network. For the NSAID-UGIB association for which major confounders are well known, further adjustment for covariates selected by the algorithm had little impact on the effect estimate.