Sample size estimation for case-crossover studies

Adjunctive virtual reality pain relief after traumatic injury: a proof-of-concept within-person randomized trial

ABSTRACT

In this study, we hypothesized that immersive virtual reality (VR) environments may reduce pain in patients with acute traumatic injuries, including traumatic brain injuries. We performed a randomized within-subject study in patients hospitalized with acute traumatic injuries, including traumatic brain injury with moderate pain (numeric pain score ≥3 of 10). We compared 3 conditions: (1) an immersive VR environment (VR Blu), (2) a content control with the identical environment delivered through nonimmersive tablet computer (Tablet Blu), and (3) a second control composed of donning VR headgear without content to control for placebo effects and sensory deprivation (VR Blank). We enrolled 60 patients, and 48 patients completed all 3 conditions. Objective and subjective data were analyzed using linear mixed-effects models. Controlling for demographics, baseline pain, and injury severity, we found differences by conditions in relieving pain (F 2,75.43 = 3.32, P = 0.042). VR Blu pain reduction was greater than Tablet Blu (-0.92 vs -0.16, P = 0.043), but VR Blu pain reduction was similar to VR Blank (-0.92 vs -1.24, P = 0.241). VR Blu was perceived as most effective by patients for pain reduction (F 2,66.84 = 16.28, P < 0.001), and changes in measures of parasympathetic activity including heart rate variability (F 2,55.511 = 7.87, P < 0.001) and pupillary maximum constriction velocity (F 2,61.41 = 3.50, 1-tailed P = 0.038) echoed these effects. There were no effects on opioid usage. These findings outlined a potential clinical benefit for mollifying pain related to traumatic injuries.

Motor Vehicle Crash Risk among Adults Undergoing General Surgery: A Retrospective Case-crossover Study

BACKGROUND

Surgery causes transient impairment in cognition and function, which may impact driving safety. The authors hypothesized that the risk of a motor vehicle crash would increase after compared to before surgery.

METHODS

The authors performed a nested case-crossover study within population-based observational data from the New Jersey Safety Health Outcomes Data Warehouse. The study included adults 18 yr or older with a valid driver's license who underwent general surgery in an acute care hospital in New Jersey between January 1, 2016, and November 30, 2017, and were discharged home. Individuals served as their own controls within a presurgery interval (56 days to 28 days before surgery) and postsurgery interval (discharge through 28 days after surgery). General surgery was defined by Common Procedural Terminology Codes. The primary outcome was a police-reported motor vehicle crash.

RESULTS

In a cohort of 70,722 drivers, the number of crashes after surgery was 263 (0.37%) compared to 279 (0.39%) before surgery. Surgery was not associated with a change in crash incidence greater than 28 days using a case-crossover design (adjusted incidence rate ratio, 0.92; 95% CI, 0.78 to 1.09; P = 0.340). Statistical interaction was present for sex and hospital length of stay. Younger versus older adults (adjusted risk ratio, 1.87; 95% CI, 1.10 to 3.18; P = 0.021) and non-Hispanic Black individuals (adjusted risk ratio, 1.96; 95% CI, 1.33 to 2.88; P = 0.001) and Hispanic individuals (adjusted risk ratio, 1.38; 95% CI, 1.00 to 1.91; P = 0.047) versus non-Hispanic White individuals had a greater risk of a crash after surgery.

CONCLUSIONS

Using population-based crash and hospital discharge data, the incidence of motor vehicle crashes over a 28-day period did not change on average before compared to after surgery. The authors provide data on crash risk after surgery and highlight specific populations at risk.

EDITOR’S PERSPECTIVE

Adjunctive virtual reality pain relief following traumatic injury: protocol for a randomised within-subjects clinical trial

INTRODUCTION

The annual mortality and national expense of the opioid crisis continue to rise in the USA (130 deaths/day, $50 billion/year). Opioid use disorder usually starts with the prescription of opioids for a medical condition. Its risk is associated with greater pain intensity and coping strategies characterised by pain catastrophising. Non-pharmacological analgesics in the hospital setting are critical to abate the opioid epidemic. One promising intervention is virtual reality (VR) therapy. It has performed well as a distraction tool and pain modifier during medical procedures; however, little is known about VR in the acute pain setting following traumatic injury. Furthermore, no studies have investigated VR in the setting of traumatic brain injury (TBI). This study aims to establish the safety and effect of VR therapy in the inpatient setting for acute traumatic injuries, including TBI.

METHODS AND ANALYSIS

In this randomised within-subjects clinical study, immersive VR therapy will be compared with two controls in patients with traumatic injury, including TBI. Affective measures including pain catastrophising, trait anxiety and depression will be captured prior to beginning sessions. Before and after each session, we will capture pain intensity and unpleasantness, additional affective measures and physiological measures associated with pain response, such as heart rate and variability, pupillometry and respiratory rate. The primary outcome is the change in pain intensity of the VR session compared with controls.

ETHICS AND DISSEMINATION

Dissemination of this protocol will allow researchers and funding bodies to stay abreast in their fields through exposure to research not otherwise widely publicised. Study protocols are compliant with federal regulation and University of Maryland Baltimore's Human Research Protections and Institutional Review Board (protocol number HP-00090603). Study results will be published on completion of enrolment and analysis, and deidentified data can be shared by request to the corresponding author.

TRIAL REGISTRATION NUMBER

NCT04356963; Pre-results.

Age effect of antipsychotic medications on the risk of sudden cardiac death in patients with schizophrenia: A nationwide case-crossover study

AIM

Research regarding the effects of age in patients with schizophrenia taking antipsychotics on the risk of sudden cardiac death is lacking. We determined the effect of patient age on the association between exposure to antipsychotics and the risk of sudden cardiac death in a nationwide schizophrenia cohort.

METHODS

From the Taiwan National Health Insurance Research Database and Department of Health Death Certification System, data of 1836 patients with schizophrenia who had experienced sudden cardiac death between 2000 and 2016 were included. A case-crossover design by using a 14-day window was applied, and subgroup analyses were performed by stratifying patients into three age subgroups (<45, 45-65, and >65 years) to assess the effect of age on the risk of sudden cardiac death in patients taking antipsychotics.

RESULTS

No association between exposure to antipsychotic agents and sudden cardiac death risk was found in patients aged >65 years who were characterized by a high burden of medical illnesses. However, zotepine significantly increased the risk of sudden cardiac death in patients aged <45 years (adjusted relative risk [RR] = 2.68, P = 0.046). Flupentixol (adjusted RR = 5.30, P = 0.004) and risperidone (adjusted RR = 1.68, P = 0.01) significantly elevated the risk of sudden cardiac death in patients aged 45-65 years.

CONCLUSION

This study suggests that individual antipsychotics pose different risks of sudden cardiac death in patients with schizophrenia across their lifespan. Clinicians should consider patient age when evaluating the risks and benefits of antipsychotic treatment.

Increased Weekly Mean PM2.5, and NO2 Are Associated With Increased Proportions of Lower Airway Granulocytes in Ontario Horses

Ambient pollution is associated with the development and exacerbation of human asthma, but whether air pollution exposure is associated with lower airway inflammation in horses has not been fully evaluated. The Air Quality Health Index (AQHI) is an online tool used by asthmatic Ontarians to modify their outdoor activity when ambient pollution is high. A single AQHI value, falling on a scale from 1 to 10⁺, is calculated from measurements of fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃). Increased AQHI values predict an increased risk for presenting to a health care provider for assessment of asthma exacerbation, with a time lag of 0-9 days after an increase. Whether ambient air pollution is a risk factor for identifying increased lower airway inflammatory cells on cytologic evaluation of bronchoalveolar lavage fluid (BALF) of horses has not yet been explored. To investigate this relationship, case data including BALF cytology preparations from horses across southern Ontario, Canada, were retrieved from the Guelph Animal Health Laboratory's archives. Spanning the years 2007-2017, 154 cases were identified within a 41- by 30-km area surrounding the cities of Guelph and Kitchener. In 78 of 154 cases, cytologic reevaluation identified increased proportions of one or a combination of BALF neutrophils (mean 5%, range 0-15%), eosinophils (mean 2%, range 0-31%), and mast cells (mean 4%, range 0-10%). To assess the effect of lagged pollutant and temperature exposures in these 78 cases, weekly mean values of AQHI, PM_2.5, NO₂, O₃, and temperature were recorded for the 4 weeks prior to the date of the horse's presentation for respiratory tract evaluation. The relationship between ambient exposures and increased proportions of lower airway granulocytes was evaluated using a case-crossover design. Single unit increases in 2-, and 3-week lagged weekly mean PM_2.5 and NO₂, were associated, respectively, with an 11% (p = 0.04, 95% confidence interval, CI = 1.01-1.22), and 24% (p = 0.03, 95% CI = 1.08-1.43) greater risk of identifying increased lower airway granulocytes. These findings suggest that exposure to increased ambient pollutants is associated with lower airway inflammation in Guelph and Kitchener area horses.