New opioid analgesic use and the risk of injurious single-vehicle crashes in drivers aged 50-80 years: A population-based matched case-control study

Peri-operative pain management in adults: a multidisciplinary consensus statement from the Association of Anaesthetists and the British Pain Society

BACKGROUND

Nearly half of adult patients undergoing surgery experience moderate or severe postoperative pain. Inadequate pain management hampers postoperative recovery and function and may be associated with adverse outcomes. This multidisciplinary consensus statement provides principles that might aid postoperative recovery, and which should be applied throughout the entire peri-operative pathway by healthcare professionals, institutions and patients.

METHODS

We conducted a directed literature review followed by a four-round modified Delphi process to formulate recommendations for organisations and individuals.

RESULTS

We make recommendations for the entire peri-operative period, covering pre-admission; admission; intra-operative; post-anaesthetic care unit; ward; intensive care unit; preparation for discharge; and post-discharge phases of care. We also provide generic principles of peri-operative pain management that clinicians should consider throughout the peri-operative pathway, including: assessing pain to facilitate function; use of multimodal analgesia, including regional anaesthesia; non-pharmacological strategies; safe use of opioids; and use of protocols and training for staff in caring for patients with postoperative pain.

CONCLUSIONS

We hope that with attention to these principles and their implementation, outcomes for adult patients having surgery might be improved.

Medications and traffic accidents involving older drivers: do Spanish primary healthcare physicians know enough?

BACKGROUND

Our aim was to evaluate Spanish family doctors' knowledge about medications that increase the risk of traffic accidents involving older drivers, and to obtain data about the involvement of family doctors in accident prevention activities and the associations between these factors and their demographic and workplace characteristics.

METHODS

A cross-sectional study of 1888 family doctors throughout Spain was carried out from 2016 to 2018. Participants completed a previously validated self-administered questionnaire that explored whether family doctors distinguished between medications associated with a high or low risk of involvement in a traffic accident, investigated the appropriateness of advice given to older patients, and physicians' involvement in preventive activities. Multiple regression models were used to estimate the adjusted association of these variables with each other and with characteristics of family doctors in the sample.

RESULTS

On a scale of 1 (never or hardly ever) to 4 (always), the indexes constructed to evaluate how often family doctors believed they should oversee the use of high-risk and low-risk medications yielded values of 3.38 for the former and 2.61 for the latter (p < 0.001). Only 24% responded correctly to all three items that inquired about the appropriateness of the advice they gave to older patients. On a scale of 1 to 4, the frequency at which family doctors gave older patients advice about preventive measures was 2.85, and only 43% reported allocating time during appointments to provide this advice. These latter two variables were directly associated with appropriate values for the index used to evaluate physicians' oversight of medications associated with a high risk. The perception of risk associated with medications and involvement in preventive activities were both greater among female participants.

CONCLUSIONS

Family doctors correctly identified medications according to their risk of playing a role in traffic accidents, although the recommendations they gave to their patients were not always appropriate. These findings, along with physicians' infrequent involvement in preventive activities, suggest a need to improve family doctors' competencies and increase the resources available to them so that they can provide their older patients with advice on ways to prevent involvement in traffic accidents.

A probabilistic bias analysis on the magnitude of unmeasured confounding: The impact of driving mileage on road traffic crashes

INTRODUCTION

Unmeasured confounding can lead to biased interpretations of empirical findings. This paper aimed to assess the magnitude of suspected unmeasured confounding due to driving mileage and simulate the statistical power required to detect a discrepancy in the effect of polypharmacy on road traffic crashes (RTCs) among older adults.

METHODS

Based on Monte Carlo Simulation (MCS) approach, we estimated 1) the magnitude of confounding of driving mileage on the association of polypharmacy and RTCs and 2) the statistical power of to detect a discrepancy from no adjusted effect. A total of 1000 studies, each of 500000 observations, were simulated.

RESULTS

Under the assumption of a modest adjusted exposure-outcome odds ratio of 1.35, the magnitude of confounding bias by driving mileage was estimated to be 16% higher with a statistical power of 50%. Only an adjusted odds ratio of at least 1.60 would be associated with a statistical power of about 80% CONCLUSION: This applied probabilistic bias analysis showed that not adjusting for driving mileage as a confounder can lead to an overestimation of the effect of polypharmacy on RTCs in older adults. Even considering a large sample, small to moderate adjusted exposure effects were difficult to be detected.

Association between prescribed opioid dose and risk of motor vehicle crashes

ABSTRACT

Opioid-involved motor vehicle traffic fatalities have increased over the past 2 decades. However, the extent to which prescribed opioids increase the risk of motor vehicle crashes remains uncertain. This study used real-world healthcare claims data to examine the association between prescription opioid dose and motor vehicle crash risk. Using nationwide US commercial insurance claims data for 2010 to 2018, we identified 772,404 adults who received incident, noncancer opioid therapy. We examined associations between daily prescription opioid dose, calculated in morphine milligram equivalents (MME) from filled prescription claims, and risk of motor vehicle crashes, assessed as diagnoses of motor vehicle injuries in claims for emergency visits, inpatient hospitalizations, and ambulance transportation. We estimated associations using a within-individual design, which ruled out all time-stable confounding. We complemented the design with time-varying statistical adjustment for other pharmacotherapies and a negative control pain pharmacotherapy analysis (with incident cyclic antidepressant prescriptions). During 2,150,009 person-years of follow-up, there were 12,123 motor vehicle crashes (5.64 crashes per 1000 person-years). In within-individual comparisons, crash risk was greater during opioid prescription periods involving doses ≤60 MME/day (odds ratio [OR], 3.86; 95% confidence interval [CI], 3.54, 4.21), >60 to 120 MME/day (OR, 5.46; 95% CI, 4.44, 6.73), and >120 MME/day (OR, 3.45; 95% CI, 2.31, 5.15) than during off-treatment periods. The negative control analysis supported the specificity of the results to opioids rather than to other processes associated with pharmacologic pain management. These findings suggest that the receipt of prescription opioids, even at doses ≤60 MME/day, is associated with an increased risk of motor vehicle crashes.

Attitudes, Beliefs, and Current Practices Carried Out by Family Physicians in Spain Regarding the Prevention of Road Injuries in Older Adults: A Nationwide Cross-Sectional Study

Purpose

The activities related to the prevention of crash injuries in older adults (PCIOA) performed by Family Physicians (FPs) have been scarcely studied. Our aim was to estimate the frequency of PCIOA activities performed by FPs in Spain and its association with attitudes and beliefs regarding this health problem.

Methods

We conducted a cross-sectional study in a nationwide sample of 1888 FPs working in Primary Health Care Services, recruited from October 2016 to October 2018. Participants completed a validated, self-administered questionnaire. Study variables included three scores related to current practices (General Practices, General Advice and Health Advice), several scores related to attitudes (General, Drawbacks and Legal), demographic and workplace characteristics. To obtain the adjusted coefficients and their 95% confidence intervals, we applied mixed effects multi-level linear regression models and the likelihood-ratio test to compare multi-level and one-level models.

Results

The frequency of PCIOA activities reported by FPs in Spain was low. The General Practices Score was 0.22/1, the General Advice Score was 1.82/4, the Health Advice Score was 2.61/4, and the General Attitudes Score was 3.08/4. The importance given to road crashes in the elderly obtained 7.16/10, the role that FPs should play in the PCIOA obtained 6.73/10, and the current perceived role obtained 3.95/10. The General Attitudes Score and the importance that FPs give themselves in the PCIOA were associated with the three Current Practices Scores.

Conclusion

The frequency of activities related to the PCIOA that FPs usually carry out in Spain is far below desirable standards. The average level of attitudes and beliefs about the PCIOA of the FPs working in Spain seems adequate. The variables of the most pronounced FPs associated with the prevention of traffic accidents in older drivers were age over 50 years, female sex and foreign nationality.

Prescription Opioid Misuse in Older Adult Surgical Patients: Epidemiology, Prevention, and Clinical Implications

ABSTRACT

The United States and many other developed nations are in the midst of an opioid crisis, with consequent pressure on prescribers to limit opioid prescribing and reduce prescription opioid misuse. This review addresses prescription opioid misuse for older adult surgical populations. We outline the epidemiology and risk factors for persistent opioid use and misuse in older adults undergoing surgery. We also address screening tools and prescription opioid misuse prevention among vulnerable older adult surgical patients (e.g., older adults with a history of an opioid use disorder), followed by clinical management and patient education recommendations. A significant plurality of older adults engaged in prescription opioid misuse obtain opioid medication for misuse from health providers. Thus, nurses can play a critical role in identifying those older adults at a higher risk for misuse and deliver quality care while balancing the need for adequate pain management against the risk for prescription opioid misuse.

New Opioid Use and Risk of Emergency Department Visits Related to Motor Vehicle Collisions in Ontario, Canada

IMPORTANCE

Opioids can impair motor skills and may affect the ability to drive; however, the association of opioid use with driving ability is not well established.

OBJECTIVE

To examine the risk of motor vehicle collisions (MVCs) among drivers starting opioid therapy compared with that among drivers starting nonsteroidal anti-inflammatory drug (NSAID) therapy.

DESIGN, SETTING, AND PARTICIPANTS

This population-based, retrospective cohort study included all residents of Ontario aged 17 years or older who started new prescription analgesic therapy between March 1, 2008, and March 17, 2019.

EXPOSURES

Initiation of opioid therapy or NSAID therapy, ascertained through prescription dispensing records in administrative data.

MAIN OUTCOMES AND MEASURES

The primary outcome was an emergency department visit for injuries sustained as a driver in an MVC during the 14 days after starting analgesic therapy. Inverse probability treatment weighting was used to balance baseline covariates, and weighted Cox proportional hazards regression models were used to assess the association between new analgesic therapy and hazard of an emergency department visit after an MVC.

RESULTS

Of the 1 454 824 individuals included in the study, 765 464 (52.6%) were new opioid recipients and 689 360 (47.4%) were new NSAID recipients. Most participants were aged 65 years or older (75.2%), and 55.2% were women. Of 194 individuals who had emergency department visits for injuries from an MVC within 14 days of initiating therapy, 98 (50.5%) were opioid recipients (3.41 per 1000 person-years; 95% CI, 2.80-4.15 per 1000 person-years) and 96 (49.5%) were NSAID recipients (3.64 per 1000 person-years; 95% CI, 2.98-4.45 per 1000 person-years). There was no significant difference in the risk of an emergency department visit for MVC injuries between opioid and NSAID recipients (weighted hazard ratio, 0.94; 95% CI, 0.70-1.25).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that the hazard of an emergency department visit for injuries relating to an MVC as a driver is similar between individuals starting prescription opioids and those starting prescription NSAIDs. These results may be useful for patients, clinicians, and caregivers when considering new analgesic therapy.

Opioid Use and Driving Performance

INTRODUCTION

The USA is in an opioid epidemic, with an increased number of individuals taking psychoactive drugs while executing the tasks of everyday life, including operating a motor vehicle. The pharmacology of opioids has been widely studied, but the effects of opioids on psychomotor function, driving performance, and the risk of motor vehicle collision remain less clear. Clinicians are faced with the challenge of controlling patient pain while also reconciling conflicting messages from the literature about how safe it is for their patients taking opioids to engage in potentially dangerous routine tasks.

DISCUSSION

This review assesses the current literature regarding opioids as they relate to neurocognitive function, driving performance, and accident risk. Manuscripts are categorized by study context and subject matter: controlled experimental administration, illicit use, prescription use, retrospective forensic toxicology, and polydrug consumption.

CONCLUSION

Illicit use, initiation of therapy, and opioid use in combination with other psychoactive medications are contexts most clearly associated with impairment of driving-related functions and/or operation of a motor vehicle. Clinicians should counsel patients on the risk of impairment when initiating therapy, when co-prescribing opioids and other psychoactive drugs, or when a patient is suspected of having an opioid use disorder.

An international multidisciplinary consensus statement on the prevention of opioid-related harm in adult surgical patients

This international multidisciplinary consensus statement was developed to provide balanced guidance on the safe peri-operative use of opioids in adults. An international panel of healthcare professionals evaluated the literature relating to postoperative opioid-related harm, including persistent postoperative opioid use; opioid-induced ventilatory impairment; non-medical opioid use; opioid diversion and dependence; and driving under the influence of prescription opioids. Recommended strategies to reduce harm include pre-operative assessment of the risk of persistent postoperative opioid use; use of an assessment of patient function rather than unidimensional pain scores alone to guide adequacy of analgesia; avoidance of long-acting (modified-release and transdermal patches) opioid formulations and combination analgesics; limiting the number of tablets prescribed at discharge; providing deprescribing advice; avoidance of automatic prescription refills; safe disposal of unused medicines; reducing the risk of opioid diversion; and better education of healthcare professionals, patients and carers. This consensus statement provides a framework for better prescribing practices that could help reduce the risk of postoperative opioid-related harm in adults.

Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia

Culpability analysis was conducted on 5000 drivers injured as a result of a vehicular collision and in whom comprehensive toxicology testing in blood was conducted. The sample included 1000 drivers for each of 5 years from approximately 5000-6000 drivers injured and taken to hospital in the State of Victoria. Logistic regression was used to investigate differences in the odds of culpability associated with alcohol and drug use and other selected crash attributes using the drug-free driver as the reference group. Adjusted odds ratios were obtained from multivariable logistic regression models in which other potentially explanatory driver and crash attributes were included. Drivers with alcohol present showed large increases in the odds of culpability similar to that seen in other studies investigating associations between blood alcohol concentration and crash risk. Methylamphetamine also showed a large increase in the odds of culpability (OR 19) compared to the reference group at both below and above 0.1 mg/L, whereas those drivers with Δ⁹-tetrahydrocannabinol (THC) present showed only modest increase in odds when all concentrations were assessed (OR 1.9, 95 %CI 1.2-3.1). Benzodiazepines in drivers also gave an increase in odds (3.2, 95 %CI 1.6-6.1), but not other medicinal drugs such as antidepressants, antipsychotics and opioids. Drivers that had combinations of impairing drugs generally gave a large increase in odds, particularly combinations of alcohol with THC or benzodiazepines, and those drivers using both THC and methamphetamine.

Geographic variation and trends in opioid-involved crash deaths in Maryland: 2006-2017

The objective of this study was to describe trends in the prevalence of opioids in driver fatalities and examine geographic variation in opioid-involved crashes at a county level. Using comprehensive toxicological data from the Office of the Chief Medical Examiner in Maryland, we examined the prevalence of opioids in all motor vehicle crash fatalities in Maryland between 2006-2017 and tested for trends to assess the statistical significance of changes in the prevalence of prescription opioids detected in these drivers over time. Opioid-involved crash deaths accounted for 10.0% of all driver deaths during the study period. The prevalence of opioids detected in fatally injured drivers increased from 8.3% in 2006 to 14.1% in 2017, (Z = -1.9, p < .05). The trends in opioid deaths do not follow broader trends in motor vehicle crash deaths; opioid-involved crashes appear to be increasing while overall motor vehicle crashes appear to be decreasing over the same period. To determine if the increase in opioid-involved crash deaths was the result of changes in pain management related to injuries sustained from the crash, we analyzed a subgroup of cases where death occurred at the scene of the crash. Within this group, there was no statistically significant increase in opioid-involved crashes during the study period. Opioid prevalence was higher in middle aged, and white drivers, and in crashes occurring in rural counties. Geographic distribution of opioid-involved crash deaths reflect broader patterns of opioid deaths overdose across the state. Irrespective of the timing of the deaths, of the drivers testing positive for opioids, 28% had elevated blood alcohol concentrations (‡ 0.01 g/dL), and 45% tested positive for other drugs.

Prescription opioids, alcohol and fatal motor vehicle crashes: a population-based case-control study

BACKGROUND

The prevalence of prescription opioid use among drivers has increased markedly in the past two decades. The purpose of this study is to assess the associations of prescription opioid use and alcohol use with the risk of fatal crash involvement in US drivers.

METHODS

We performed a population-based case-control study using toxicological testing data from two national data systems. Cases (n = 3606) were drivers involved in fatal motor vehicle crashes selected from the Fatality Analysis Reporting System and controls (n = 15,600) were drivers participating in the 2007 and 2013 National Roadside Surveys of Alcohol and Drug Use by Drivers. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) of fatal crash involvement associated with prescription opioid use with and without the presence of alcohol.

RESULTS

Overall, cases were significantly more likely than controls to test positive for prescription opioids (5.0% vs. 3.7%, p < 0.001), alcohol (56.2% vs. 7.1%, p < 0.0001), and both substances (2.2% vs. 0.2%, p < 0.001). Relative to drivers testing negative for prescription opioids and alcohol, the adjusted ORs of fatal crash involvement were 1.72 (95% CI: 1.37, 2.17) for those testing positive for prescription opioids and negative for alcohol, 17.92 (95% CI: 16.19, 19.84) for those testing positive for alcohol and negative for prescription opioids, and 21.89 (95% CI: 14.38, 33.32) for those testing positive for both substances. The interaction effect on fatal crash risk of prescription opioid use and alcohol use was not statistically significant on either additive or multiplicative scale.

CONCLUSIONS

Prescription opioid use is associated with a significantly increased risk of fatal crash involvement independently of alcohol use. Concurrent use of prescription opioids and alcohol is associated with a 21-fold increased risk of fatal crash involvement.

Lack of Consensus in Physician Recommendations Regarding Return to Driving After Cervical Spine Surgery

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The goal of this study is to investigate how surgeons differ in collar and narcotic use, as well as return to driving recommendations following cervical spine surgeries and the associated medico-legal ramifications of these conditions.

SUMMARY OF BACKGROUND DATA

Restoration of quality of life is one of the main goals of cervical spine surgery. Patients frequently inquire when they may safely resume driving after cervical spine surgery. There is no consensus regarding postoperative driving restrictions. This study addresses how surgeons differ in their recommendations concerning cervical immobilization, narcotic analgesia, and suggested timeline of return to driving following cervical spine surgery.

METHODS

Surgeons at the Cervical Spine Research Society annual meeting completed anonymous surveys assessing postoperative patient management following fusion and nonfusion cervical spine surgeries.

RESULTS

Seventy percent of surgeons returned completed surveys (n = 71). About 80.3% were orthopedic surgeons and 94.2% completed a spine fellowship. Experienced surgeons (>15 years in practice) were more likely to let patients return to driving within 2 weeks than less experienced surgeons (47.1% vs. 24.3%, P = 0.013) for multilevel anterior discectomy and fusion (ACDF) and laminectomy with fusion procedures. There were no differences between surgeons practicing inside and outside the USA for prescribing collars or return to driving time. Cervical collars were used more for fusions than nonfusions (57.7% vs. 31.0%, P = 0.001). Surgeons reported 75.3% of patients ask when they may resume driving. For cervical fusions, 31.4% of surgeons allowed their patients to resume driving while restricting them with collars for longer durations. Furthermore, 27.5% of surgeons allowed their patients to resume driving while taking narcotics postoperatively.

CONCLUSION

This survey-based study highlights the lack of consensus regarding patient "fitness to drive" following cervical spine surgery. The importance of establishing evidence-based guidelines is critical, as recommendations for driving in the postoperative period may have significant medical, legal, and financial implications.

LEVEL OF EVIDENCE

5.

Use of prescription opioids and motor vehicle crashes: A meta analysis

OBJECTIVES

Opioid analgesics are a major driver of the ongoing opioid epidemic in the United Sates, accounting for about two thirds of drug overdose fatalities. There are conflicting reports regarding the effects of prescription opioids on driving safety. A meta-analysis was performed to assess the epidemiologic evidence for the association between use of prescription opioids and the risk of motor vehicle crashes.

METHODS

Studies examining the association between driver prescription opioid use and motor vehicle crash involvement or crash culpability and published in English were identified through a comprehensive search of 15 bibliographic databases. Eligible articles were fully reviewed and summarized. Study quality was assessed using the Newcastle-Ottawa Scale. Overall summary odds ratios (ORs) and 95% confidence intervals (CIs) were estimated through random effects models.

RESULTS

Overall, 15 studies were included in the meta-analysis; of them, 10 assessed the association of prescription opioid use with the risk of crash involvement and 5 assessed the association of prescription opioid use with the risk of crash culpability. Reported crude ORs associated with prescription opioid use ranged from 1.15 to 8.19 for the risk of crash involvement and from 0.75 to 2.78 for the risk of crash culpability. Summary ORs based on pooled data were 2.29 (95% CI: 1.51, 3.48) for crash risk and 1.47 (95% CI: 1.01, 2.13) for crash culpability.

CONCLUSIONS

The existent epidemiologic evidence indicates that use of prescription opioids by drivers is associated with significantly increased risks of crash involvement and crash culpability. Further research is needed to understand the epidemiologic patterns of prescription opioid use in the driver population and the interaction effects between opioids and alcohol on driving safety.

Assessing the practice of palliative care doctors: what driving advice do they give patients with advanced disease?

BACKGROUND

There is little research and no clear guidelines for clinicians to follow when instructing patients with advanced disease about driving.

AIMS

To investigate current practice in providing advice to patients with advanced disease and identify areas of consensus or variation with the Australian driving guidelines.

METHODS

An online survey was distributed to Australian members of the Australian and New Zealand Society of Palliative Medicine. Responses were analysed using descriptive statistics.

RESULTS

The survey was distributed to 322 Australian and New Zealand Society of Palliative Medicine members and received 92 responses (29% response rate). Most respondents were aware of the driving guidelines (76%) and about half of the respondents had read the driving guidelines (55%). The majority of respondents had been asked to provide advice about driving to their patient or patient's caregiver (91%). Most respondents had asked a patient to stop driving (94%), but only 27% had reported a patient to the Driver Licensing Authority. Only 14% of respondents were in consensus with the guidelines in providing driving advice to a patient with asymptomatic brain metastases. Most doctors (64%) advise patients to refrain temporarily from driving post-short-acting oral morphine, with 4 h (36%) being the most common time period for not driving.

CONCLUSIONS

This is the first survey investigating the practice of Australian doctors in assessing fitness to drive of patients with advanced disease. The survey found wide variability in practice and substantial discordance with current driving guidelines.

Malignant Cerebellar Edema Subsequent to Accidental Prescription Opioid Intoxication in Children

We present two recent cases of toddlers who developed malignant cerebellar edema subsequent to accidental ingestion of prescription opioids. Both children presented acute neurological decline, hydrocephalus, and tonsillar herniation requiring emergent ventricular drain placement, suboccipital craniectomy, and partial cerebellectomy. Together with several other reports, these cases suggest the existence of an uncommon yet severe syndrome of acute opioid-induced malignant cerebellar edema. We hypothesize that the condition results from a combination of primary opioid receptor-mediated changes in neuronal metabolism that are exacerbated by secondary hypoxic insult. If recognized promptly, this syndrome can be treated with emergent neurosurgical intervention with good clinical outcomes. These cases also illustrate the unintended consequences and innocent victims of the spiraling prescription opioid epidemic, which will likely increase in prevalence. Recognition of this syndrome by clinicians is thus critical.

Trends in Prescription Opioids Detected in Fatally Injured Drivers in 6 US States: 1995-2015

OBJECTIVES

To assess the time trends in prescription opioids detected in fatally injured drivers.

METHODS

We analyzed 1995 to 2015 Fatality Analysis Reporting System data from California, Hawaii, Illinois, New Hampshire, Rhode Island, and West Virginia of toxicological tests for drivers fatally injured within 1 hour of a crash (n = 36 729). We used the Cochran-Armitage test for trend to assess the statistical significance of changes in the prevalence of prescription opioids detected in these drivers over time.

RESULTS

The prevalence of prescription opioids detected in fatally injured drivers increased from 1.0% (95% confidence interval [CI] = 0.5, 1.4) in 1995 to 7.2% (95% CI = 5.7, 8.8) in 2015 (Z = -9.04; P < .001). Prescription opioid prevalence was higher in female than in male drivers (4.4% vs 2.9%; P < .001). Of the drivers testing positive for prescription opioids, 30.0% had elevated blood alcohol concentrations (≥ 0.01 g/dL), and 66.9% tested positive for other drugs.

CONCLUSIONS

The prevalence of prescription opioids detected in fatally injured drivers has increased in the past 2 decades. The need to assess the effect of increased prescription opioid use on traffic safety is urgent.

New, Occasional, and Frequent Use of Zolpidem or Zopiclone (Alone and in Combination) and the Risk of Injurious Road Traffic Crashes in Older Adult Drivers: A Population-Based Case-Control and Case-Crossover Study

BACKGROUND

Previous studies on the effect of zolpidem or zopiclone use on the risk of road traffic crashes (RTCs) have shown mixed results.

OBJECTIVE

Our objective was to determine the association between zolpidem or zopiclone use (as separate drugs or combined) and the occurrence of injurious RTCs among older adult drivers.

METHODS

This was a population-based matched case-control and case-crossover study based on secondary data linked together from Swedish national registers. Cases were drivers aged 50-80 years involved in a vehicle crash resulting in injuries between January 2006 and December 2009 for the case-control study (n = 27,096) and from February 2006 to December 2009 for the case-crossover study (n = 26,586). For the first design, four controls were matched to each case by sex, age, and residential area, and exposure was categorized into new, occasional, and frequent use of zolpidem only, zopiclone only, and combined zolpidem and zopiclone. For the case-crossover study, newly dispensed zolpidem or zopiclone users were assessed during the 28 days prior to the crash and compared with an equally long control period using a 12-week washout period. Matched adjusted odds ratios (OR) were computed using conditional logistic regression.

RESULTS

Increased ORs for all users were observed. In the case-control study, the highest odds were seen among newly initiated zolpidem-only users involved in single-vehicle crashes (adjusted OR 2.27; 95% confidence interval [CI] 1.21-4.24), followed by frequent combined zolpidem and zopiclone users [adjusted OR 2.20; CI 1.21-4.00]. In the case-crossover, newly initiated treatment with zolpidem or zopiclone showed an increased risk that was highest in the 2 weeks after the start of the treatment (OR 2.66; 95% CI 1.04-6.81).

CONCLUSIONS

These results provide more compelling evidence for the role of zolpidem or zopiclone in the occurrence of RTCs among older adults, not only in frequent users, but also at the beginning of treatment.