SEQUENTIALLY ADJUSTED RANDOMIZATION TO FORCE BALANCE IN CONTROLLED TRIALS WITH UNKNOWN PREVALENCE OF COVARIATES: APPLICATION TO ALCOHOLISM RESEARCH

Randomized controlled trial evaluating a collaborative model of care for transitioning children with medical complexity from hospital to home healthcare: Study protocol

This article describes the study protocol for an evaluation of an innovative model of care that supports home health nurses (HHN) who serve children with medical complexity (CMC). CMC constitute a small proportion of children, but have very high need for health services, are hospitalized frequently, and account for significant proportion of pediatric healthcare expenditures. High-quality home health nursing services are important for CMC, but models of care of home healthcare, after discharge of CMC from the hospital, have not been tested. Our project aims are to develop, implement, and test a model of care, called ICollab, to improve home healthcare delivery for CMC. The ICollab model consists of collaboration between HHN, primary-care physicians and clinicians of the complex care program of a tertiary-care children's hospital in the care of CMC. In this randomized clinical trial, we will recruit 110 CMC discharged home on home health nursing services. The intervention group (n = 55) will receive the ICollab intervention for 6 months post-discharge from the hospital, in addition to usual care. Children in the control group (n = 55) will receive only usual care. Outcome measures will include healthcare utilization metrics (hospitalization rates, emergency room visit rates, and days to readmission), caregiver burden and caregiver satisfaction with home healthcare, HHN retention, and HHN collaboration with other healthcare providers. We hypothesize that ICollab will reduce healthcare utilization and caregiver burden, and improve caregiver satisfaction with home healthcare, increase HHN retention, and increase HHN collaboration with other healthcare providers. Results of this study have the potential to provide a critically needed evidence-base for interventions to improve the quality of healthcare delivery for CMC. This study is registered on clinicaltrials.gov (NCT03978468) and is ongoing.

Neurocognitive variation in smoking behavior and withdrawal: genetic and affective moderators

A burgeoning literature suggests that attentional factors are associated with smoking behavior (e.g. direct nicotine effects and smoking withdrawal). This study examined differences in attentional processing between nonsmokers, satiated smokers and overnight nicotine-deprived smokers by comparing the amplitude of the P300 (P3) component of the event-related brain potential (ERP) elicited during a go-nogo task. We also examined the moderating effects of a common dopamine receptor genotype and state negative affect (SNA) on this ERP index of attention. Nonsmokers relative to smokers had greater nogo P3 amplitude. Carrying the A1 allele at the dopamine receptor D2 (DRD2) Taq1A polymorphism site moderated the effects of withdrawal on nogo P3 amplitude, suggesting the A1 allele is a vulnerability marker for withdrawal-related attentional deficits. Increased SNA also predicted attenuated P3 amplitude among deprived smokers. These findings suggest that DRD2 status and SNA moderate the effects of smoking status and withdrawal on neurocognitive variation during attentional processing. This research contributes to a better understanding of the role of individual differences and attentional processing in smoking behavior.

Randomization in substance abuse clinical trials

BACKGROUND

A well designed randomized clinical trial rates as the highest level of evidence for a particular intervention's efficacy. Randomization, a fundamental feature of clinical trials design, is a process invoking the use of probability to assign treatment interventions to patients. In general, randomization techniques pursue the goal of providing objectivity to the assignment of treatments, while at the same time balancing for treatment assignment totals and covariate distributions. Numerous randomization techniques, each with varying properties of randomness and balance, are suggested in the statistical literature. This paper reviews common randomization techniques often used in substance abuse research and an application from a National Institute on Drug Abuse (NIDA)-funded clinical trial in substance abuse is used to illustrate several choices an investigator faces when designing a clinical trial.

RESULTS

Comparisons and contrasts of randomization schemes are provided with respect to deterministic and balancing properties. Specifically, Monte Carlo simulation is used to explore the balancing nature of randomization techniques for moderately sized clinical trials. Results demonstrate large treatment imbalance for complete randomization with less imbalance for the urn or adaptive scheme. The urn and adaptive randomization methods display smaller treatment imbalance as demonstrated by the low variability of treatment allocation imbalance. For all randomization schemes, covariate imbalance between treatment arms was small with little variation between adaptive schemes, stratified schemes and unstratified schemes given that sample sizes were moderate to large.

CONCLUSION

We develop this paper with the goal of reminding substance abuse researchers of the broad array of randomization options available for clinical trial designs. There may be too quick a tendency for substance abuse researchers to implement the fashionable urn randomization schemes and other highly adaptive designs. In many instances, simple or blocked randomization with stratification on a major covariate or two will accomplish the same objectives as an urn or adaptive design, and it can do so with more simply implemented schedules and without the dangers of overmatching. Furthermore, the proper analysis, fully accounting for the stratified design, can be conducted.