Benzodiazepines and elderly drivers: a comparison of pharmacoepidemiological study designs

Antibiotic-Associated Acute Kidney Injury Among Older Adults: A Case-Crossover Study

BACKGROUND AND OBJECTIVES

Drug-related acute kidney injury is quite common in older adults. The associated drugs, including antibiotics, are often co-prescribed. The objective of this study was to ascertain antibiotic-associated acute kidney injury (AKI) in older adults aged 65 years or above in New Zealand using a case-crossover study design.

METHODS

The International Statistical Classification of Diseases and Related Health Problems, tenth revision, Australian modification code N17.x was used to identify all individuals aged 65 years and above with a diagnosis of incident AKI on admission between 1 January 2005 and 31 December 2020, from the New Zealand National Minimum Data Set. A case-crossover cohort for antibiotic exposures, with a 3 day case period and two 30 day washout periods, summed up to a 66 day study period, was created. Using conditional logistic regression, the changed odds of AKI due to exposure to an antibiotic was calculated as matched odds ratios and their 95% confidence intervals.

RESULTS

A total of 2399 incident cases of AKI were identified between 2005 and 2020 among older adults. The adjusted odds of consuming sulfamethoxazole/trimethoprim antibiotic during the case period was 3.57 times (95% CI 2.86-4.46) higher than the reference period among the incident AKI cases. Fluoroquinolone utilization was also associated with incident AKI (adjusted OR = 2.56; 95% CI 1.90-3.46).

CONCLUSION

The potential of sulfamethoxazole/trimethoprim and fluoroquinolones to be associated with AKI raises the significant need for vigilant prescribing of these antibiotics in older adults.

Association of benzodiazepines, Z-drugs, pregabalin, and melatonin with traffic accidents: A nationwide cohort and case-crossover study in Danish adults

BACKGROUND

Benzodiazepines, Z-drugs, pregabalin, and melatonin (BZPMs) have been associated with a higher risk of traffic accidents, but the evidence is inconsistent, and lacking for newer drugs.

AIM

To examine the association of BZPMs with risk of traffic accidents.

METHODS

All Danish adults (n = 3,823,588) were followed for redeemed prescriptions of BZPM and for incident traffic accidents registered in Danish registers from 2002 through 2018. Associations were examined in cohort and case-crossover designs using Cox proportional hazard and conditional logistic regression with adjustment for co-variables.

RESULTS

A total of 19.3% (n = 738,019) of all participants initiated treatment with BZPMs. During the mean follow-up of 10.3 years, 595,173(15.5%) of participants were involved in a traffic accident. In the cohort analysis, all BZPMs besides pregabalin were associated with a higher risk of traffic accidents in adults below 70 years, with chlordiazepoxide showing the strongest association (hazard ratio (HR)_{age 18-49} = 1.76, 95% confidence interval (CI): 1.67-1.86 and HR_{age 50-69} = 1.84, 95% CI: 1.70-2.00). In the older age groups, the specific BZPM medications were associated with lower or no risk of traffic accidents. However, in case-time-crossover analysis with inherited control for confounders, no BZPM medication was positively associated with traffic accidents, except for chlordiazepoxide, which had a higher odds ratio in middle-aged group (1.62, 95% CI: 1.15-2.29).

CONCLUSIONS

This study does not fully support that BZPM use is a risk factor for traffic accidents. However, a positive association was found for chlordiazepoxide, which is approved for treatment of acute alcohol withdrawal.

Benzodiazepine Overuse in Elders: Defining the Problem and Potential Solutions

Objective To determine the prevalence of benzodiazepine use in adults aged 65 and older at two West Virginia academic medical centers as phase one of a benzodiazepine deprescribing strategy.  Design Cross-sectional Setting Two academic hospitals in West Virginia with 107,504 hospitalized adults age 65 and older from the years 2010 to 2018 with information on admission medication use.  Measurements Use of benzodiazepines based on presence on the admission medication list. Demographics, select co-morbidities, and laboratory tests were also recorded.  Results The prevalence of benzodiazepine use was 13.5% and use remained relatively constant with increasing age over 65, even in those over age 89.  Conclusion Efforts aimed at assessing the true need for benzodiazepine use and deprescribing need to be employed, particularly with advancing age.

Benzodiazepine Treatment and Fracture Risk in Young Persons With Anxiety Disorders

BACKGROUND

Benzodiazepines are commonly prescribed to treat anxiety disorders and have been associated with falls and fractures in older adults. It is unknown whether benzodiazepines increase fracture risk in youth. We examined whether youth with anxiety disorders initiating benzodiazepine treatment have an increased risk of fractures compared with youth initiating selective serotonin reuptake inhibitors (SSRIs).

METHODS

We used claims from commercially insured children (6-17 years) and young adults (18-24) with a recent anxiety disorder diagnosis, initiating benzodiazepines or SSRIs (2008-2016). Youth were followed until fracture, treatment discontinuation or switching, disenrollment, 3 months, or December 31, 2016. The primary end point was diagnostic codes for upper and lower limb fractures. Incident fracture rates, incident rate ratios (IRRs), and incident rate differences (IRDs) were estimated with propensity score inverse probability of treatment weighting.

RESULTS

The cohort included 120 715 children and 179 768 young adults. In children, crude fracture rates during treatment were 33.1 per 1000 person-years (PYs) for benzodiazepine initiators and 25.1 per 1000 PYs for SSRI initiators. Adjusted IRR and IRD were 1.53 (95% confidence interval [CI]: 0.94-2.50) and 13.4 per 1000 PYs. Risk was heightened in children initiating long-acting benzodiazepines versus SSRIs (adjusted IRR = 2.30 [95% CI: 1.08-4.91]). Fracture rates were lower in young adults, with minimal differences between treatments (adjusted IRR = 0.85 [95% CI: 0.57-1.27]; adjusted IRD = -1.3 per 1000 PYs).

CONCLUSIONS

An increased rate of fractures in children, but not young adults, with anxiety disorders initiating benzodiazepine treatment compared to SSRI treatment suggests a need for increased caution in the weeks after benzodiazepine initiation in children.

Can clinical practice indicator relating to long-acting benzodiazepine use in the elderly be easily generated in a hospital setting?

BACKGROUND

To improve the appropriate use of long-acting benzodiazepine (la.bzd) prescriptions in the elderly, the Haute Autorité de Santé (HAS) has developed clinical practice indicators (CPI). The alert indicator (AI) evaluates the prevalence of la.bzd prescription among older people. The mastering indicator (MI) corresponds to the prevalence of elderly with a justified, i.e., appropriate, la.bzd prescription among all the elderly with la.bzd prescriptions.

OBJECTIVE

The objective of this study was to test the feasibility of routine generation of CPI regarding la.bzd prescriptions among the elderly in the hospital setting.

DESIGN

This was a retrospective study.

SETTING

The study was conducted in two university hospitals located in Paris.

SUBJECT

Eligible cases were patients aged 65 years and older who were hospitalized in acute care units from January to June 2014.

METHOD

The AI calculation was based on information extracted from medical databases from these hospitals. The appropriateness of la.bzd prescription was assessed by a physician and a pharmacist and was based on review of computerized patient records and prescriptions, using an ad hoc algorithm. The MI was then calculated. Variation in the level of indicators was explored according to the characteristics of patients and of their hospitalization using chi² test. Factors associated with a potentially inappropriate prescription (PIP) of la.bzd were studied using univariate and multivariate logistic regression.

RESULT

Among the 4167 patients included in the study, 362 had la.bzd prescriptions, i.e., the AI was 9%. Prescriptions were found to be appropriate for 83 patients, i.e., the MI was 23% and PIP was 77%. The MI varied between 13 and 31% according to characteristics of patients and of hospitalization. In multivariate analysis, factors associated with PIP were age, number of comorbidities, type of care unit, and concurrent prescription of a neuroleptic or hypnotic.

CONCLUSION

Generation of the AI was routinely possible but only for acute care units with computerized prescriptions, corresponding to 78% of patients. Production of the MI has required medical record review for all patients with a la.bzd prescription and cannot be automated. However, difficulties in generating the MI have identified areas for significant improvement. Moreover, strategies to improve the care of older people with a la.bzd prescription could be targeted using characteristics of patients and of hospitalization associated with PIP. The future deployment of a single electronic medical record in all care departments would make it easier to mine the data and make possible automated production of CPI.

Clinical Practice Guideline: Benign Paroxysmal Positional Vertigo (Update)

Objective

This update of a 2008 guideline from the American Academy of Otolaryngology—Head and Neck Surgery Foundation provides evidence-based recommendations to benign paroxysmal positional vertigo (BPPV), defined as a disorder of the inner ear characterized by repeated episodes of positional vertigo. Changes from the prior guideline include a consumer advocate added to the update group; new evidence from 2 clinical practice guidelines, 20 systematic reviews, and 27 randomized controlled trials; enhanced emphasis on patient education and shared decision making; a new algorithm to clarify action statement relationships; and new and expanded recommendations for the diagnosis and management of BPPV.

Purpose

The primary purposes of this guideline are to improve the quality of care and outcomes for BPPV by improving the accurate and efficient diagnosis of BPPV, reducing the inappropriate use of vestibular suppressant medications, decreasing the inappropriate use of ancillary testing such as radiographic imaging, and increasing the use of appropriate therapeutic repositioning maneuvers. The guideline is intended for all clinicians who are likely to diagnose and manage patients with BPPV, and it applies to any setting in which BPPV would be identified, monitored, or managed. The target patient for the guideline is aged ≥18 years with a suspected or potential diagnosis of BPPV. The primary outcome considered in this guideline is the resolution of the symptoms associated with BPPV. Secondary outcomes considered include an increased rate of accurate diagnoses of BPPV, a more efficient return to regular activities and work, decreased use of inappropriate medications and unnecessary diagnostic tests, reduction in recurrence of BPPV, and reduction in adverse events associated with undiagnosed or untreated BPPV. Other outcomes considered include minimizing costs in the diagnosis and treatment of BPPV, minimizing potentially unnecessary return physician visits, and maximizing the health-related quality of life of individuals afflicted with BPPV.

Action Statements

The update group made strong recommendations that clinicians should (1) diagnose posterior semicircular canal BPPV when vertigo associated with torsional, upbeating nystagmus is provoked by the Dix-Hallpike maneuver, performed by bringing the patient from an upright to supine position with the head turned 45° to one side and neck extended 20° with the affected ear down, and (2) treat, or refer to a clinician who can treat, patients with posterior canal BPPV with a canalith repositioning procedure. The update group made a strong recommendation against postprocedural postural restrictions after canalith repositioning procedure for posterior canal BPPV. The update group made recommendations that the clinician should (1) perform, or refer to a clinician who can perform, a supine roll test to assess for lateral semicircular canal BPPV if the patient has a history compatible with BPPV and the Dix-Hallpike test exhibits horizontal or no nystagmus; (2) differentiate, or refer to a clinician who can differentiate, BPPV from other causes of imbalance, dizziness, and vertigo; (3) assess patients with BPPV for factors that modify management, including impaired mobility or balance, central nervous system disorders, a lack of home support, and/or increased risk for falling; (4) reassess patients within 1 month after an initial period of observation or treatment to document resolution or persistence of symptoms; (5) evaluate, or refer to a clinician who can evaluate, patients with persistent symptoms for unresolved BPPV and/or underlying peripheral vestibular or central nervous system disorders; and (6) educate patients regarding the impact of BPPV on their safety, the potential for disease recurrence, and the importance of follow-up. The update group made recommendations against (1) radiographic imaging for a patient who meets diagnostic criteria for BPPV in the absence of additional signs and/or symptoms inconsistent with BPPV that warrant imaging, (2) vestibular testing for a patient who meets diagnostic criteria for BPPV in the absence of additional vestibular signs and/or symptoms inconsistent with BPPV that warrant testing, and (3) routinely treating BPPV with vestibular suppressant medications such as antihistamines and/or benzodiazepines. The guideline update group provided the options that clinicians may offer (1) observation with follow-up as initial management for patients with BPPV and (2) vestibular rehabilitation, either self-administered or with a clinician, in the treatment of BPPV.

Methods to control for unmeasured confounding in pharmacoepidemiology: an overview

Background Unmeasured confounding is one of the principal problems in pharmacoepidemiologic studies. Several methods have been proposed to detect or control for unmeasured confounding either at the study design phase or the data analysis phase. Aim of the Review To provide an overview of commonly used methods to detect or control for unmeasured confounding and to provide recommendations for proper application in pharmacoepidemiology. Methods/Results Methods to control for unmeasured confounding in the design phase of a study are case only designs (e.g., case-crossover, case-time control, self-controlled case series) and the prior event rate ratio adjustment method. Methods that can be applied in the data analysis phase include, negative control method, perturbation variable method, instrumental variable methods, sensitivity analysis, and ecological analysis. A separate group of methods are those in which additional information on confounders is collected from a substudy. The latter group includes external adjustment, propensity score calibration, two-stage sampling, and multiple imputation. Conclusion As the performance and application of the methods to handle unmeasured confounding may differ across studies and across databases, we stress the importance of using both statistical evidence and substantial clinical knowledge for interpretation of the study results.

Do case-only designs yield consistent results across design and different databases? A case study of hip fractures and benzodiazepines

Background

The case‐crossover (CXO) and self‐controlled case series (SCCS) designs are increasingly used in pharmacoepidemiology. In both, relative risk estimates are obtained within persons, implicitly controlling for time‐fixed confounding variables.

Objectives

To examine the consistency of relative risk estimates of hip/femur fractures (HFF) associated with the use of benzodiazepines (BZD) across case‐only designs in two databases (DBs), when a common protocol was applied.

Methods

CXO and SCCS studies were conducted in BIFAP (Spain) and CPRD (UK). Exposure to BZD was divided into non‐use, current, recent and past use. For CXO, odds ratios (OR; 95%CI) of current use versus non‐use/past were estimated using conditional logistic regression adjusted for co‐medications (AOR). For the SCCS, conditional Poisson regression was used to estimate incidence rate ratios (IRR; 95%CI) of current use versus non/past‐use, adjusted for age. To investigate possible event‐exposure dependence the relative risk in the 30 days prior to first BZD exposure was also evaluated.

Results

In the CXO current use of BZD was associated with an increased risk of HFF in both DBs, AOR_BIFAP = 1.47 (1.29–1.67) and AOR_CPRD = 1.55 (1.41–1.70). In the SCCS, IRRs for current exposure was 0.79 (0.72–0.86) in BIFAP and 1.21 (1.13–1.30) in CPRD. However, when we considered separately the 30‐day pre‐exposure period, the IRR for current period was 1.43 (1.31–1.57) in BIFAP and 1.37 (1.27–1.47) in CPRD.

Conclusions

CXO designs yielded consistent results across DBs, while initial SCCS analyses did not. Accounting for event‐exposure dependence, estimates derived from SCCS were more consistent across DBs and designs. © 2015 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.

Prescription of antidepressants and the risk of road traffic crash in the elderly: a case-crossover study

AIM

To investigate the impact of antidepressants on the risk of road traffic crash in the elderly.

METHODS

Reports from the Universal Quebec Automobile Insurance Agency database were matched with data on antidepressant prescription from the Quebec Health Insurance Agency. The case-crossover analysis consisted in comparing exposure during a period immediately before the crash with exposure during earlier periods, for the same subject.

RESULTS

One hundred and nine thousand four hundred and six drivers between 66 and 84 years of age involved in a traffic crash between 1988 and 2000 were included. Two thousand nine hundred and nineteen (2.7%) were exposed to an antidepressant on the day of the crash. Case-crossover analysis found an increased risk of crash in drivers with a prescription of antidepressants before their crash when compared with a prescription of antidepressants 4 to 8 months before the crash (OR = 1.19, 95% CI 1.08, 1.30 to 1.42. 95% CI 1.30, 1.55). With the most recent control periods, results were not significant.

CONCLUSION

A patient's mental state is probably more similar between two periods that are close to each other than up to 8 months before. Consequently, the risk of crash is likely to be linked to symptoms of depression.

Alcohol and drug use as predictors of intentional injuries in two emergency departments in British Columbia

BACKGROUND

While a substantial literature exists demonstrating a strong association of alcohol and intentional injury, less is known about the association of intentional injury with recreational drug use, either alone, or in combination with alcohol.

OBJECTIVES

The risk of intentional injury due to alcohol and other drug use prior to injury is analyzed in a sample of emergency department (ED) patients.

METHODS

Logistic regression was used to examine the predictive value of alcohol and drug use on intentional versus non-intentional injury in a probability sample of ED patients in Vancouver, BC (n = 436).

RESULTS

Those reporting only alcohol use were close to four times more likely (OR = 3.73) to report an intentional injury, and those reporting alcohol combined with other drug(s) almost 18 times more likely (OR = 17.75) than those reporting no substance use. Those reporting both alcohol and drug use reported drinking significantly more alcohol (15.7 drinks) than those reporting alcohol use alone (5 drinks).

CONCLUSIONS

These data suggest that alcohol in combination with other drugs may be more strongly associated with intentional injury than alcohol alone.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

The strong association of alcohol combined with other drug use on injury may be due to the increased amount of alcohol consumed by those using both substances, and is an area requiring more research with larger samples of intentional injury patients.

Risk of road accident associated with the use of drugs: a systematic review and meta-analysis of evidence from epidemiological studies

This paper is a corrigendum to a previously published paper where errors were detected. The errors have been corrected in this paper. The paper is otherwise identical to the previously published paper. A systematic review and meta-analysis of studies that have assessed the risk of accident associated with the use of drugs when driving is presented. The meta-analysis included 66 studies containing a total of 264 estimates of the effects on accident risk of using illicit or prescribed drugs when driving. Summary estimates of the odds ratio of accident involvement are presented for amphetamines, analgesics, anti-asthmatics, anti-depressives, anti-histamines, benzodiazepines, cannabis, cocaine, opiates, penicillin and zopiclone (a sleeping pill). For most of the drugs, small or moderate increases in accident risk associated with the use of the drugs were found. Information about whether the drugs were actually used while driving and about the doses used was often imprecise. Most studies that have evaluated the presence of a dose-response relationship between the dose of drugs taken and the effects on accident risk confirm the existence of a dose-response relationship. Use of drugs while driving tends to have a larger effect on the risk of fatal and serious injury accidents than on the risk of less serious accidents (usually property-damage-only accidents). The quality of the studies that have assessed risk varied greatly. There was a tendency for the estimated effects of drug use on accident risk to be smaller in well-controlled studies than in poorly controlled studies. Evidence of publication bias was found for some drugs. The associations found cannot be interpreted as causal relationships, principally because most studies do not control very well for potentially confounding factors.

Variable selection on large case-crossover data: application to a registry-based study of prescription drugs and road traffic crashes

PURPOSE

In exploratory analyses of pharmacoepidemiological data from large populations with large number of exposures, both a conceptual and computational problem is how to screen hypotheses using probabilistic reasoning, selecting drug classes or individual drugs that most warrant further hypothesis testing.

METHODS

We report the use of a shrinkage technique, the Lasso, in the exploratory analysis of the data on prescription drugs and road traffic crashes, resulting from the case-crossover matched-pair interval approach described by Orriols and colleagues (PLoS Med 2010; 7:e1000366). To prevent false-positive results, we consider a bootstrap-enhanced version of the Lasso. To highlight the most stable results, we extensively examine sensitivity to the choice of referent window.

RESULTS

Antiepileptics, benzodiazepine hypnotics, anxiolytics, antidepressants, antithrombotic agents, mineral supplements, drugs used in diabetes, antiparkinsonian treatment, and several cardiovascular drugs showed suspected associations with road traffic accident involvement or accident responsibility.

CONCLUSION

These results, in relation to other findings in the literature, provide new insight and may generate new hypotheses on the association between prescription drugs use and impaired driving ability.

Psychotropic drugs and risk of motor vehicle accidents: a population-based case-control study

AIM

To examine comprehensively the relationship between exposure to four classes of psychotropic drugs including antipsychotics, antidepressants, benzodiazepines (BZDs) and Z-drugs, and motor vehicle accidents (MVAs).

METHOD

The authors conducted a matched case-control study of 5183 subjects with MVAs and 31 093 matched controls, identified from the claims records of outpatient service visits during the period from 2000 to 2009. Inclusion criteria were defined as subjects aged equal to or more than 18 years and involved in MVAs. Conditional logistic regressions with covariates adjustment (including urbanity, psychiatric and non-psychiatric outpatient visits and Charlson comorbidity score) were applied to examine the effect of four classes of psychotropic drugs on MVAs.

RESULTS

Significant increased risk of MVAs was found in subjects taking antidepressants within 1 month (adjusted odds ratio (AOR) 1.73, 95% confidence interval (CI) 1.34, 2.22), 1 week (AOR 1.71, 95% CI 1.29, 2.26), and 1 day (AOR 1.70, 95% CI 1.26, 2.29) before MVAs occurred. Similar results were observed in subjects taking benzodiazepines (BZDs) (AOR 1.56, 95% CI 1.38, 1.75 for 1 month; AOR 1.64, 95% CI 1.43, 1.88 for 1 week, and AOR 1.62, 95% CI 1.39, 1.88 for 1 day) and Z-drugs (AOR 1.42, 95% CI 1.14, 1.76 for 1 month, AOR 1.37, 95% CI 1.06, 1.75 for 1 week, AOR 1.34, 95% CI 1.03, 1.75 for 1 day), but not antipsychotics. Moreover, significant dose effects of antidepressants (equal to or more than 0.6-1.0 DDD), BZDs (equal to or more than 0.1-0.5 DDD) and Z-drugs (more than 1 DDD) were observed, respectively, on the risk of experiencing an MVA.

CONCLUSION

Taken together, subjects taking antidepressants, BZDs and Z-drugs, separately, should be particularly cautioned for their increasing risk of MVAs.

Alcohol as a trigger for medical emergencies

In this paper, our goal is to report relative risks of the impact of alcohol consumption 6 hours prior to medical emergencies presenting in the emergency department for 8,346 patients in seven countries using data from the Emergency Room Collaborative Alcohol Analysis Project. We found that alcohol increased the risk of a medical emergency by 2.17 times (confidence interval: 1.78-2.65), and those without a regular pattern of heavy drinking and those younger showed a greater risk. Acute alcohol is associated not only with injury but also with medical emergencies. More studies are needed on the acute role of alcohol in medical emergencies, preferably with data on the type of medical emergencies.

Short-term exposure to antidepressant drugs and risk of acute angle-closure glaucoma among older adults

Acute angle-closure glaucoma (AACG) is an ocular emergency that may be precipitated by certain types of medications. Antidepressant drugs can affect a number of neurotransmitters, which are involved in the regulation of the iris, which may precipitate AACG. We used a case-crossover study design to investigate the association between recent exposure to antidepressant drugs and AACG. We identified patients with AACG among adults aged 66 years or older between 1998 and 2010 in Ontario using linked population-based administrative databases. We identified intermittent users of antidepressant medications through prescription drug claims in the year preceding AACG. We determined antidepressant exposure in the period immediately before AACG and compared it with antidepressant exposure in 2 earlier control periods. We used conditional logistic regression to determine the odds ratio for antidepressant exposure in the hazard period compared with the control periods. A total of 6470 patients with AACG occurred during the study period. The mean age of the patients was 74.3 years, and 66% were female. Overall, 5.6% of individuals were intermittent users of antidepressant drugs in the year preceding AACG. The odds ratio for any antidepressant exposure in the period immediately preceding AACG was 1.62 (95% confidence interval, 1.16-2.26). An increased risk of AACG was also observed in several subgroups. We conclude that recent exposure to antidepressant drugs is associated with an increased risk of AACG. Clinicians should remain vigilant for the development of this uncommon but potentially serious adverse event after initiating antidepressant therapy.

A comparison of pharmacoepidemiological study designs in medication use and traffic safety research

In order to explore how the choice of different study designs could influence the risk estimates, a case–crossover and case–time–control study were carried out and their outcomes were compared with those of a traditional case–control study design that evaluated the association between the exposure to psychotropic medications and the risk of having a motor vehicle accident (MVA). A record-linkage database availing data for 3,786 cases and 18,089 controls during the period 2000–2007 was used. The study designs (i.e., case–crossover and case–time–control) were derived from published literature, and the following psychotropic medicines were examined: antipsychotics, anxiolytics, hypnotics and sedatives, and antidepressants, stratified in the two groups selective serotonin reuptake inhibitors (SSRIs) and other antidepressants. Moreover, in order to further investigate the effects of frequency of psychoactive medication exposure on the outcomes of the case–crossover analysis, the data were also stratified by the number of defined daily doses (DDDs) and days of medication use in the 12 months before the motor vehicle accident. Three-thousand seven-hundred fifty-two cases were included in this second part of the case–crossover analysis. The case–crossover design did not show any statistically significant association between psychotropic medication exposure and MVA risk [e.g., SSRIs—Adj. OR = 1.00 (95 % CI: 0.69–1.46); Anxiolytics—Adj. OR = 0.95 (95 % CI: 0.68–1.31)]. The case–time–control design only showed a borderline statistically significant increased traffic accident risk in SSRI users [Adj. OR = 1.16 (95 % CI: 1.01–1.34)]. With respect to the stratifications by the number of DDDs and days of medication use, the analyses showed no increased traffic accident risk associated with the exposure to the selected medication groups [e.g., SSRIs, <20 DDDs—Adj. OR = 0.65 (95 % CI: 0.11–3.87); SSRIs, 16–150 days—Adj. OR = 0.55 (95 % CI: 0.24–1.24)]. In contrast to the above-mentioned results, our recent case–control study found a statistically significant association between traffic accident risk and exposure to anxiolytics [Adj. OR = 1.54 (95 % CI: 1.11–2.15)], and SSRIs [Adj. OR = 2.03 (95 % CI: 1.31–3.14)]. Case–crossover and case–time–control analyses produced different results than those of our recent case–control study (i.e., case–crossover and case–time–control analyses did not show any statistically significant association whereas the case–control analysis showed an increased traffic accident risk in anxiolytic and SSRI users). These divergent results can probably be explained by the differences in the study designs. Given that the case–crossover design is only appropriate for short-term exposures and the case–time–control design is an elaboration of this latter, it can be concluded that, probably, these two approaches are not the most suitable ones to investigate the relation between MVA risk and psychotropic medications, which, on the contrary, are often use chronically.

Within-person study designs had lower precision and greater susceptibility to bias because of trends in exposure than cohort and nested case-control designs

OBJECTIVE

To compare precision and apparent bias between cohort, nested case-control, self-controlled case series, case-crossover, and case-time-control study designs.

STUDY DESIGN AND SETTING

Study designs were implemented to evaluate the association between thiazolidinediones (TZDs) and heart failure, TZDs and fracture, and liver enzyme-inducing anticonvulsants and fracture.

RESULTS

Effect estimates were similar for the cohort and case-control study; for the association between TZDs and fracture in women, the hazard ratio was 1.36 (1.18, 1.56) and odds ratio (OR) was 1.44 (1.21, 1.70). For this clinical example, the self-controlled case series gave upward bias when follow-up was censored at the outcome (incidence rate ratio [IRR], 7.08; 4.96, 10.09) but was otherwise unbiased (IRR, 1.41; 1.14, 1.75). The retrospective case-crossover OR was 3.24 (2.18, 4.80), which was reduced by either bidirectional sampling (OR, 1.20; 0.98, 1.46) or with the case-time-control design (OR, 1.40; 1.09, 1.81). Findings on apparent bias were similar for the other two clinical examples. In each clinical example, within-person designs had considerably lower precision than the cohort or case-control study designs.

CONCLUSION

When long-term exposures are analyzed, within-person study designs may have lower precision and greater susceptibility to bias. Bias may be reduced by sampling follow-up both before and after the outcome or with the case-time-control study design.

Psychotropic medications and crash risk in older drivers: a review of the literature

OBJECTIVE

. An extensive review of Australian and international literature was undertaken, examining the association between psychotropic medications and crash risk involving older drivers.

METHODS

. The review summarizes the findings in experimental and epidemiological studies related to (a) prevalence of psychotropic medication use among older drivers; (b) side effects of driving under the influence of psychotropic medications; and (c) association between psychotropic medications and crash risk for older drivers.

RESULTS

. Current evidence indicates that several types of psychotropic medications have the potential to impair driving ability and increase the risk of crash involvement. A major limitation is that few studies have specifically examined the effects on older drivers, despite the fact that the majority of the population using psychotropic medications are older. Discussion. More knowledge about the safety of therapeutic use of psychotropic medications is needed. Large-scale, whole-population, epidemiological studies, such as data linkage studies, may be the optimal study design.

Medications in long-term care: when less is more

Attention has been drawn to the potential risks of several medications in the long-term care setting. Most of these medications deemed as inappropriate affect the central nervous system and are indicated only for select populations with specific conditions. Many of these drugs are prescribed without clear indications and continued indefinitely without critical decision-making about the potentially salutary effects of discontinuing medications. This article describes the increasing awareness of potentially inappropriate prescribing in the long-term care setting and reviews the rationale for why various types of medications are deemed inappropriate, with a focus on agents that affect central nervous system functioning.

A population-based case-crossover study of polyethylene glycol use and acute renal failure risk in the elderly

AIM: To evaluate the possibility of an association between polyethylene glycol (PEG) and acute renal failure (ARF) in elderly patients using a health insurance claims database.

METHODS: We conducted a population-based case-crossover study using information obtained from Korean Health Insurance Review and Assessment Service (HIRA) claims from January 1, 2005 to December 31, 2005 (Seoul, Korea). The study population consisted of elderly patients who received PEG prior to experiencing their first ARF-related hospitalization from April 1, 2005 to December 31, 2005. For each patient, one case and two control periods were matched. PEG use in a 2- or 4-wk window period prior to hospitalization for ARF was compared with PEG use in two earlier 2- or 4-wk control window periods. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% CI, adjusting for concomitant uses of diuretics, angiotensin converting enzyme inhibitors, non-steroidal anti-inflammatory drugs, antibiotics, anti-cancer drugs, and contrast media.

RESULTS: Within the HIRA database which contained 1 093 262 elderly patients, 1156 hospitalized ARF cases were identified. Among these cases, PEG was prescribed to 17 (1.5%) patients before hospitalization. The adjusted ORs when applying the 2- and 4-wk window periods were 0.4 (95% CI: 0.03-5.24) and 2.1 (95% CI: 0.16-27.78), respectively.

CONCLUSION: No increased risk of ARF was found in elderly PEG users. However, based on the limited number of study subjects, further analysis should be performed to confirm these results.

The relationship between benzodiazepine use and traffic accidents: A systematic literature review

In many countries, benzodiazepines are the most commonly used and misused psychoactive medicinal drugs. Results of epidemiological studies investigating the association between benzodiazepine use and traffic accidents seem to be inconclusive or inconsistent at first sight. However, the outcome of epidemiological studies may be influenced by several methodological factors like study design, study population, exposure measurement, outcome definitions and possible confounders. Our objective was to conduct a systematic literature review of epidemiological studies that investigated the association between benzodiazepine use and traffic accidents, including related outcomes like culpability and injury or accident severity. We searched EMBASE, PubMed and Forensic Science Abstracts 3/0 (FORS) for references included in these databases at 1 June 2009 using the term 'benzodiazepines' in combination with 'driving performance' or 'accident risk' or 'traffic accident'. For inclusion in this review, the study design had to be comparative, include road users involved in accidents and provide specific data about benzodiazepines. Sixty-six studies were included in the review. The study populations varied from the general (driving) population, accident-involved road users with or without injury and persons admitted to a hospital to fatally injured accident-involved drivers. Exposure assessment was performed by using toxicological results, prescription data or questionnaires. The divergent study populations and comparison groups and the variety of methods used to express the outcome of interest hampered comparison between results. Evidence is growing that exposure to benzodiazepines is related to increased accident risk. The literature indicates that the greatest accident risk is associated with the use of long half-life benzodiazepines, increasing dosage and the first few weeks of use of benzodiazepines. Clear evidence of increased culpability associated with benzodiazepine use is scarce. More research has to be done to elucidate the relationship between benzodiazepine use and injury severity.

Alcohol consumption among Canadians taking benzodiazepines and related drugs

PURPOSE

Benzodiazepines and related drugs (BZDs) are widely used for the treatment of anxiety, insomnia and other conditions. The combination of BZDs with alcohol increases risk for oversedation, abuse, dependence and accidents. This study examines drinking behaviour among Canadians taking BZDs.

METHODS

We use data from cycle 1.2 of the Canadian Community Health Survey, a large (n = 36,984) population survey conducted in 2002 by Statistics Canada. We use bivariate methods and logistic regression to test the independent association between BZD use and 2 levels of recent drinking in the general population, and then examine associations between drinking and sociodemographic factors within the group of BZD users.

RESULTS

Any drinking and heavy drinking are less common among users of BZDs than among other respondents, but these differences are small (any drinking, OR = 0.77, p = 0.02; heavy drinking, OR = 0.81, p = 0.13) when differences in respondent characteristics are controlled statistically. Among BZD users, any drinking is associated with male sex, younger age and not meeting criteria for a past-year anxiety disorder. Heavy drinking is associated only with younger age.

CONCLUSIONS

Heavy alcohol use is uncommon among users of BZDs, and the combination of alcohol and BZD use is rare in the general population. Differences between BZD users and others are not large when other factors are taken into account, however, which may call into question the effectiveness of physician and pharmacist warnings against this combination. People treated for an anxiety disorder with BZDs may be less likely to use alcohol than those taking them for other indications.

[Case-crossover design: Basic essentials and applications]

Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subject's exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design.

Clinical Practice Guideline: Benign Paroxysmal Positional Vertigo

Objectives:

This guideline provides evidence-based recommendations on managing benign paroxysmal positional vertigo (BPPV), which is the most common vestibular disorder in adults, with a lifetime prevalence of 2.4 percent. The guideline targets patients aged 18 years or older with a potential diagnosis of BPPV, evaluated in any setting in which an adult with BPPV would be identified, monitored, or managed. This guideline is intended for all clinicians who are likely to diagnose and manage adults with BPPV.

Purpose:

The primary purposes of this guideline are to improve quality of care and outcomes for BPPV by improving the accurate and efficient diagnosis of BPPV, reducing the inappropriate use of vestibular suppressant medications, decreasing the inappropriate use of ancillary tests such as radiographic imaging and vestibular testing, and to promote the use of effective repositioning maneuvers for treatment. In creating this guideline, the American Academy of Otolaryngology—Head and Neck Surgery Foundation selected a panel representing the fields of audiology, chiropractic medicine, emergency medicine, family medicine, geriatric medicine, internal medicine, neurology, nursing, otolaryngology–head and neck surgery, physical therapy, and physical medicine and rehabilitation.

Results

The panel made strong recommendations that 1) clinicians should diagnose posterior semicircular canal BPPV when vertigo associated with nystagmus is provoked by the Dix-Hallpike maneuver. The panel made recommendations against 1) radiographic imaging, vestibular testing, or both in patients diagnosed with BPPV, unless the diagnosis is uncertain or there are additional symptoms or signs unrelated to BPPV that warrant testing; and 2) routinely treating BPPV with vestibular suppressant medications such as antihistamines or benzodiazepines. The panel made recommendations that 1) if the patient has a history compatible with BPPV and the Dix-Hallpike test is negative, clinicians should perform a supine roll test to assess for lateral semicircular canal BPPV; 2) clinicians should differentiate BPPV from other causes of imbalance, dizziness, and vertigo; 3) clinicians should question patients with BPPV for factors that modify management including impaired mobility or balance, CNS disorders, lack of home support, and increased risk for falling; 4) clinicians should treat patients with posterior canal BPPV with a particle repositioning maneuver (PRM); 5) clinicians should reassess patients within 1 month after an initial period of observation or treatment to confirm symptom resolution; 6) clinicians should evaluate patients with BPPV who are initial treatment failures for persistent BPPV or underlying peripheral vestibular or CNS disorders; and 7) clinicians should counsel patients regarding the impact of BPPV on their safety, the potential for disease recurrence, and the importance of follow-up. The panel offered as options that 1) clinicians may offer vestibular rehabilitation, either self-administered or with a clinician, for the initial treatment of BPPV and 2) clinicians may offer observation as initial management for patients with BPPV and with assurance of follow-up. The panel made no recommendation concerning audiometric testing in patients diagnosed with BPPV.

Disclaimer:

This clinical practice guideline is not intended as a sole source of guidance in managing benign paroxysmal positional vertigo. Rather, it is designed to assist clinicians by providing an evidence-based framework for decision-making strategies. The guideline is not intended to replace clinical judgement or establish a protocol for all individuals with this condition, and may not provide the only appropriate approach to diagnosing and managing this problem. ® 2008 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved.

The case-crossover study design in pharmacoepidemiology

In the study of the association of transient drug exposures with acute outcomes, the case-crossover design is an efficient alternative to the case-control approach. This design based exclusively on the case series uses within-subject comparisons of drug exposures over time to estimate the rate ratio of the outcome associated with the drug under study. This design inherently removes the biasing effects of unmeasured, time-invariant confounding factors from the estimated rate ratio, but is sensitive to several assumptions. We illustrated the case-crossover design and explored its sensitivity using data from 4028 cases of gastrointestinal bleeding from the General Practice Research Database in assessing the effects of the drug warfarin. We compared the use of different time window lengths to assess exposure and considered the use of a case-time-control design to account for exposure time trends. The case-crossover approach found no excess risk of bleeding with warfarin exposure [rate ratio 0.98; 95% confidence interval (CI): 0.74-1.28] using a 1-month time window. When we restricted the analysis to subjects with truly transient drug exposure, defined by 1 to 3 prescriptions in the previous year, the rate ratio was 2.59 (95% CI: 1.42-4.74). To consider the longer 1-year exposure time window, the case-time-control approach was used and resulted in a rate ratio of 1.72 (95% CI: 1.08-2.43). In conclusion, the case-crossover design is potentially a powerful approach to assess the risk of drugs. This design is, however, highly sensitive to assumptions about intermittency of drug use and the length of the exposure time window, as demonstrated with the example of bleeding associated with warfarin use.

Statin induced myopathy and myalgia: time trend analysis and comparison of risk associated with statin class from 1991-2006

BACKGROUND

Statins are widely used as a cholesterol lowering medication, reduce cardiovascular mortality and morbidity in high risk patients; and only rarely cause serious adverse drug reactions (ADRs). UK primary care databases of morbidity and prescription data, which now cover several million people, have potential for more powerful analytical approaches to study ADRs including adjusting for confounders and examining temporal effects.

METHODS

Case-crossover design in detecting statin associated myopathy ADR in 93, 831 patients, using two independent primary care databases (1991-2006). We analysed risk by drug class, by disease code and cumulative year, exploring different cut-off exposure times and confounding by temporality.

RESULTS

Using a 12 and 26 week exposure period, large risk ratios (RR) are associated with all classes of statins and fibrates for myopathy: RR 10.6 (9.8-11.4) and 19.9 (17.6-22.6) respectively. At 26 weeks, the largest risks are with fluvastatin RR 33.3 (95% CI 16.8-66.0) and ciprofibrate (with previous statin use) RR 40.5 (95% CI 13.4-122.0). AT 12 weeks the differences between cerivastatin and atorvastatin RR for myopathy were found to be significant, RR 2.05 (95% CI 1.2-3.5), and for rosuvastatin and fluvastatin RR 3.0 (95% CI 1.6-5.7). After 12 months of statin initiation, the relative risk for myopathy for all statins and fibrates increased to 25.7 (95% CI 21.8-30.3). Furthermore, this signal was detected within 2 years of first events being recorded. Our data suggests an annual incidence of statin induced myopathy or myalgia of around 11.4 for 16, 591 patients or 689 per million per year.

CONCLUSION

There may be differential risks associated with some classes of statin and fibrate. Myopathy related to statin or fibrate use may persist after a long exposure time (12 months or more). These methods could be applied for early detection of harmful drug side effects, using similar primary care diagnostic and prescribing data.