In this study, the authors assessed the impact of particulate air pollution on first respiratory hospitalization. Study subjects were children less than 3 years of age living in Vancouver, British Columbia, who had their first hospitalization as a result of any respiratory disease (ICD-9 codes 460-519) during the period from June 1, 1995, to March 31, 1999. The authors used logistic regression to estimate the associations between ambient concentrations of particulate matter (PM) and first hospitalization. The adjusted odds ratios for first respiratory hospitalization associated with mean and maximal PM10-2.5 with a lag of 3 days were 1.12 (95% confidence interval: 0.98, 1.28) and 1.13 (1.00, 1.27). After adjustment for gaseous pollutants, the corresponding odds ratios were 1.22 (1.02, 1.48) and 1.14 (0.99, 1.32). The data indicated the possibility of harmful effects from coarse PM on first hospitalization for respiratory disease in early childhood.
Ambient air pollution has been associated with increased cardiovascular morbidity and mortality. In Reykjavik, Iceland, air pollutant concentrations exceed official health limits several times every year. The aim was to study the association of concentrations of NO2, O3, PM10, and H2S in the Reykjavik capital area with the dispensing of anti-angina pectoris medication, glyceryl trinitrate to the inhabitants.
Data on daily dispensing of glyceryl trinitrate, were retrieved from the Icelandic Medicines Registry. Data on hourly concentrations of NO2, O3, PM10, and H2S were obtained from the Environment Agency of Iceland. A case-crossover design was used, based on the dispensing of glyceryl trinitrate to 5,246 individuals (=18 years) between 2005 and 2009.
For every 10 µg/m3 increase of NO2 and O3 3-day mean concentrations, the odds ratio (OR) for daily dispensing of glyceryl trinitrates was 1.136 (95% confidence intervals (CI) 1.069-1.207) and 1.094 (95% CI 1.029-1.163) at lag 0, and OR was 1.096 (95% CI 1.029-1.168) and 1.094 (95% CI 1.028-1.166) at lag 1, respectively.
These findings suggest that NO2 and O3 ambient air concentrations may adversely affect cardiovascular health, as measured by the dispensing of glyceryl trinitrates for angina pectoris. Further, the findings suggest that data on the dispensing of medication may be a valuable health indicator when studying the effect of air pollution on cardiovascular morbidity.
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Contradictory results were published from two studies in the late 1990s about the effects of long half-life benzodiazepine use on the risk of motor vehicle crashes (MVCs) in the elderly. The use of different study designs could explain the differences observed in these studies.
The results of an unmatched case-control study were compared to those of a case-crossover study using the same prescription claims database to determine whether the current use of benzodiazepines increased the risk of MVCs.
There were 5579 cases and 12 911 controls identified between the years 1990 and 1993 in the province of Quebec, Canada. The case-control approach demonstrated an increased rate of injurious MVC associated with the current use of long-acting benzodiazepines [odds ratio (OR) 1.45; 95% confidence interval (CI): 1.12-1.88]. The case-crossover approach applied to all cases did not show any association [OR 0.99; 95%CI: 0.83-1.19]. However, among the cases restricted to subjects with four or less prescriptions filled in the previous year, corresponding more to transient exposures, the OR was elevated [OR 1.53; 95%CI: 1.08-2.16].
Differences in study design and analysis may explain some of the discrepancies in previous results. Both study designs provide evidence that long-acting benzodiazepines appear to be associated with an increased risk of MVC.
Comment In: Pharmacoepidemiol Drug Saf. 2007 Aug;16(8):850-317636552
OBJECTIVE: To describe a research project assessing the role of bullying at school as an injury trigger and the modification effect of the socio-economic environment of the victims. Preliminary results are also presented. METHOD: A case-crossover and a case-referent design were combined. The study base consisted of all children aged 10-15 years residing in the Stockholm county in 2000-02. Cases were recruited at the county's children hospital and interviewed shortly after the injury, using a specially designed questionnaire. RESULTS: Preliminary analyses (261 interviews) reveal that about two injured children out of 10 reported having been bullied during the school term. Also, one out of 10 had been bullied shortly enough before the injury for bullying to be considered as a trigger. The circumstances of occurrence of those injuries varied. CONCLUSION: Bullying, apart from being frequent in the school environment, is quite likely to act as an injury trigger.
This study examined the impact of transportation infrastructure at intersection and non-intersection locations on bicycling injury risk.
In Vancouver and Toronto, we studied adult cyclists who were injured and treated at a hospital emergency department. A case-crossover design compared the infrastructure of injury and control sites within each injured bicyclist's route. Intersection injury sites (N=210) were compared to randomly selected intersection control sites (N=272). Non-intersection injury sites (N=478) were compared to randomly selected non-intersection control sites (N=801).
At intersections, the types of routes meeting and the intersection design influenced safety. Intersections of two local streets (no demarcated traffic lanes) had approximately one-fifth the risk (adjusted OR 0.19, 95% CI 0.05 to 0.66) of intersections of two major streets (more than two traffic lanes). Motor vehicle speeds less than 30 km/h also reduced risk (adjusted OR 0.52, 95% CI 0.29 to 0.92). Traffic circles (small roundabouts) on local streets increased the risk of these otherwise safe intersections (adjusted OR 7.98, 95% CI 1.79 to 35.6). At non-intersection locations, very low risks were found for cycle tracks (bike lanes physically separated from motor vehicle traffic; adjusted OR 0.05, 95% CI 0.01 to 0.59) and local streets with diverters that reduce motor vehicle traffic (adjusted OR 0.04, 95% CI 0.003 to 0.60). Downhill grades increased risks at both intersections and non-intersections.
These results provide guidance for transportation planners and engineers: at local street intersections, traditional stops are safer than traffic circles, and at non-intersections, cycle tracks alongside major streets and traffic diversion from local streets are safer than no bicycle infrastructure.
It has been shown that newly initiated opioid therapy increases the risk of fall-related injuries. Yet, it remains to be determined whether drug-drug interactions can affect this negative effect, for instance with drugs inhibiting cytochrome P4502D6 (CYP2D6) that metabolizes codeine and also has a partial effect on tramadol and oxycodone. Our aim was to investigate how CYP2D6-inhibiting drugs contribute to explaining the risk of fall-related injuries for newly initiated opioid treatments with codeine, tramadol or oxycodone. Data from a Swedish national case-cross over study were revisited. This study identified a total of 167,257 fall-related injuries leading to hospitalization that occurred between 1 May 2006 and 31 December 2009 and linked information about dispensed drugs to them. Use of newly dispensed opioids in the 28 days before fall-related injury with and without CYP2D6-inhibiting drugs was compared with an earlier control period. For codeine, there was a two-times increased risk with concomitant CYP2D6-inhibiting drug use (OR, 1.76; 95% CI 1.40-2.20) and a three-times risk increase without (OR, 3.17; 95% CI 2.88-3.50). For tramadol, the risks were doubled when CYP2D6-inhibiting drugs were used (OR, 2.19; 95% CI 1.84-2.60) and tripled without their use (OR, 3.04; 95% CI 2.82-3.27). The risks were about the same for oxycodone, morphine, fentanyl and buprenorphine irrespective of CYP2D6-inhibiting drug use. In newly initiated opioid therapies, drug-drug interactions from concomitant use of CYP2D6-inhibiting drugs are associated with a lower risk of fall-related injury for codeine and tramadol that undergo metabolism via CYP2D6, but not for other opioids.
OBJECTIVE: Our objectives were to study anger as a trigger of acute myocardial infarction (MI) and to explore potential effect modification by usual behavioral patterns related to hostility. METHODS: This study was a case-crossover study within the Stockholm Heart Epidemiology Program. Exposure in the period immediately preceding MI was compared with exposure during a control period for each case. From April 1993 to December 1994, 699 patients admitted to coronary care units in Stockholm County were interviewed. RESULTS: During a period of 1 hour after an episode of anger, with an intensity of at least "very angry," the relative risk of MI was 9.0 (95% CI, 4.4-18.2). In patients with premonitory symptoms, the time of disease initiation may be misclassified. When restricting the analyses to those without such symptoms, the trigger risk was 15.7 (95% CI, 7.6-32.4). The possibility of examining effect modification was limited by a lack of statistical power (eight exposed cases). Results of the analyses suggested, however, an increased trigger effect among subjects reporting nonhostile usual behavior patterns, nonovert strategies of coping with aggressive situations (not protesting when being treated unfairly), and nonuse of beta-blockers. CONCLUSIONS: The hypothesis that anger may trigger MI is further supported, with an increased risk lasting for approximately 1 hour after an outburst of anger. It is suggested that the trigger risk may be modified by personal behavior patterns.
To study possible triggering of first events of acute myocardial infarction by heavy physical exertion, the authors conducted a case-crossover analysis (1993-1994) within a population-based case-referent study in Stockholm County, Sweden (the Stockholm Heart Epidemiology Program). Interviews were carried out with 699 myocardial infarction patients after onset of the disease. These cases represented 47 percent of all cases in the study base, and 70 percent of all nonfatal cases. The relative risk from vigorous exertion was 6.1 (95% confidence interval: 4.2, 9.0). The rate difference was 1.5 per million person-hours, and the attributable proportion was 5.7 percent. The risk was modified by physical fitness, with an increased risk being seen among sedentary subjects as in earlier studies, but the data also suggested a U-shaped association. In addition, the trigger effect was modified by socioeconomic status. Premonitory symptoms were common, and this implies risks of reverse causation bias and misclassification of case exposure information that require methodological consideration. Different techniques (the use of the usual-frequency type of control information, a pair-matched analysis, and a standard case-referent analysis) were applied to overcome the threat of misclassification of control exposure information. A case-crossover analysis in a random sample of healthy subjects resulted in a relative risk close to unity, as expected.
There is growing epidemiological evidence that opioids may increase the risk of unintentional injuries and it is plausible that the time of initiation is most critical in that respect. Studies on fall-related injuries remain few, limited and mostly focused on specific groups of elderly patients.
The objective of this study was to assess the short-term effects of newly prescribed opioids on the risk of fall-related injuries in the general adult population.
A case-crossover design was applied on national register data linking, at the individual level, fall-injury information involving adults aged 18 years and above identified in the Swedish National Inpatient Register (during the period 1 May 2006 to 31 December 2009) and dispensed drugs from the Swedish Prescribed Drug Register (n=167,257 cases with a first fall-related injury). All types of opioid substances were considered, classified according to the Anatomical Therapeutic Chemical (ATC) classification system. We investigated newly dispensed opioids 28 days preceding the injury, compared with an earlier, and equally long, control period following a 3-month washout period. Conditional logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (CI). The analyses were also conducted stratified by age group, by type of fall and for each period of 1 week during the 28-day period.
From among the fall-injured patients, 7,450 patients (4.5%) had a new opioid dispensation within 28 days prior to the injury, of which the most frequent types were tramadol (2.0%) and codeine (1.1%). Consistently increased risks of fall-related injuries associated with a new prescription of any opioid were found and they were most pronounced among young adults, 18-29 years of age (OR, 7.17; 95% CI 5.04-10.2). The closer the dispensation date to the injury, the higher the odds: an OR of 5.14 (95% CI 4.76-5.55) during the first week of opioid treatment and 1.23 (95% CI 1.10-1.38) for the fourth week. Of the documented falls, the risk was most pronounced for falls from 'another, high level' (OR, 5.33; 95% CI 3.99-7.10).
Newly prescribed opioids may trigger injurious falls. The effect lowers over time and is less pronounced with increasing age. The risk is also higher for fall from height.
Percutaneous coronary intervention (PCI) is a plausible triggering factor for stroke, yet the magnitude of this excess risk remains unclear. This study aimed to quantify the transient change in risk of stroke for up to 12 weeks after PCI. We applied the case-crossover method, using data from the Norwegian Patient Register on all hospitalizations in Norway in the period of 2008 to 2014. The relative risk (RR) of ischemic stroke was highest during the first 2 days after PCI (RR 17.5, 95% confidence interval [CI] 4.2 to 72.8) and decreased gradually during the following weeks. The corresponding RR was 2.0 (95% CI 1.2 to 3.3) 4 to 8 weeks after PCI. The RR for women was more than twice as high as for men during the first 4 postprocedural weeks, RR 10.5 (95% CI 3.8 to 29.3) and 4.4 (95% CI 2.7 to 7.2), respectively. Our results were compatible with an increased RR of hemorrhagic stroke 4 to 8 weeks after PCI, but the events were few and the estimates were very imprecise, RR 3.0 (95% CI 0.8 to 11.1). The present study offers new knowledge about PCI as a trigger for stroke. Our estimates indicated a substantially increased risk of ischemic stroke during the first 2 days after PCI. The RR then decreased gradually but stayed elevated for 8 weeks. Increased awareness of this vulnerable period after PCI in clinicians and patients could contribute to earlier detection and treatment for patients suffering a postprocedural stroke.