Modeling the Cost-Effectiveness of Interventions to Reduce Suicide Risk Among Hospital Emergency Department Patients.

OBJECTIVE: This study estimated the expected cost-effectiveness and population impact of outpatient interventions to reduce suicide risk among patients presenting to general hospital emergency departments (EDs), compared with usual care. Several such interventions have been found efficacious, but none is yet widespread, and the cost-effectiveness of population-based implementation is unknown. METHODS: Modeled cost-effectiveness analysis compared three ED-initiated suicide prevention interventions previously found to be efficacious-follow-up via postcards or caring letters, follow-up via telephone outreach, and suicide-focused cognitive-behavioral therapy (CBT)-with usual care. Primary outcomes were treatment costs, suicides, and life-years saved, evaluated over the year after the index ED visit. RESULTS: Compared with usual care, adding postcards improved outcomes and reduced costs. Adding telephone outreach and suicide-focused CBT, respectively, improved outcomes at a mean incremental cost of $4,300 and $18,800 per life-year saved, respectively. Monte Carlo simulation (1,000 repetitions) revealed the chance of incremental cost-effectiveness to be a certainty for all three interventions, assuming societal willingness to pay ≥$50,000 per life-year. These main findings were robust to various sensitivity analyses, including conservative assumptions about effect size and incremental costs. Population impact was limited by low sensitivity of detecting ED patients' suicide risk, and health care delivery inefficiencies. CONCLUSIONS: The highly favorable cost-effectiveness found for each outpatient intervention provides a strong basis for widespread implementation of any or all of the interventions. The estimated population benefits of doing so would be enhanced by increasing the sensitivity of suicide risk detection among individuals presenting to general hospital EDs.

Economic evaluation of strategies to reduce sudden cardiac death in young athletes.

OBJECTIVE: There is controversy about appropriate methods to reduce sudden cardiac death (SCD) in young athletes, but there is limited evidence on costs or consequences of alternative strategies. The objective of this study was to evaluate the cost-effectiveness of adding electrocardiogram (ECG) screening to the currently standard practice of preparticipation history and physical examination (H&P) to reduce SCD. METHODS: Decision analysis modeling by using a societal perspective, with annual Markov cycles from age 14 until death. Three screening strategies were evaluated: (1) H&P, with cardiology referral if abnormal (current standard practice); (2) H&P, plus ECG after negative H&P, and cardiology referral if either is abnormal; and (3) ECG only, with cardiology referral if abnormal. Children identified with SCD-associated cardiac abnormalities were restricted from sports and received cardiac treatment. Main outcome measures were costs of screening and treatment, quality-adjusted life years (QALYs), and premature deaths averted. RESULTS: Relative to strategy 1, incremental cost-effectiveness is $68800/QALY for strategy 2 and $37700/QALY for strategy 3. Monte Carlo simulation revealed the chance of incremental cost-effectiveness compared with strategy 1 was 30% for strategy 2 and 66% for strategy 3 (assumed willingness to pay ≤$50000/QALY). Compared with strategy 1, strategy 2 averted 131 additional SCDs at $900000 per case, and strategy 3 averted 127 SCDs at $600000 per case. CONCLUSIONS: Under a societal willingness to pay threshold of $50000/QALY, adding ECGs to current preparticipation evaluations for athletes is not cost-effective, with costs driven largely by false-positive findings.

Modeled economic evaluation of alternative strategies to reduce sudden cardiac death among children treated for attention deficit/hyperactivity disorder.

BACKGROUND: Stimulants are widely used to treat children with attention deficit/hyperactivity disorder and may increase the risk for sudden cardiac death (SCD). We examined the cost-effectiveness of pretreatment screening with ECG for reducing SCD risk in children diagnosed with attention deficit/hyperactivity disorder who are candidates for stimulant medication. Method and Results- We constructed a state-transition Markov model with 10 annual cycles spanning 7 to 17 years of age. Taking a societal perspective, we compared the cost-effectiveness of 3 screening strategies: (1) performing a history and physical examination with cardiology referral if abnormal (current standard of care); (2) performing a history and physical examination plus ECG after negative history and physical examination, with cardiology referral if either is abnormal; and (3) performing a history and physical examination plus ECG, with cardiology referral only if ECG is abnormal. Children identified with SCD-associated cardiac abnormalities would be restricted from stimulants and from playing competitive sports. The expected incremental cost-effectiveness over strategy 1 was $39,300 and $27,200 per quality-adjusted life-year for strategies 2 and 3, respectively. Monte Carlo simulation found that the chance of incremental cost-effectiveness was 55% for strategy 2 and 71% for strategy 3 (willingness to pay < or =$50,000 per quality-adjusted life-year). Both strategies 2 and 3 would avert 13 SCDs per 400,000 children seeking stimulant treatment for ADHD, for a cost of $1.6 million per life for strategy 2 and $1.2 million per life for strategy 3. CONCLUSIONS: Relative to current practice, adding ECG screening to history and physical examination pretreatment screening for children with attention deficit/hyperactivity disorder has borderline cost-effectiveness for preventing SCD. Relative cost-effectiveness may be improved by basing cardiology referral on ECG alone. Benefits of ECG screening arise primarily by restricting children identified with SCD risk from competitive sports.

Convergence of submodality-specific input onto neurons in primary somatosensory cortex.

At the somatosensory periphery, slowly adapting type 1 (SA1) and rapidly adapting (RA) afferents respond very differently to step indentations: SA1 afferents respond throughout the entire stimulus interval (sustained response), whereas RA afferents respond only at stimulus onset (on response) and offset (off response). We recorded the responses of cortical neurons to step indentations and found many neurons in areas 3b and 1 to exhibit properties that are intermediate between these two extremes: These neurons responded during the sustained portion of the stimulus and also at the offset of the stimulus. Several lines of evidence indicate that these neurons, which exist in large proportions even at these early stages of somatosensory cortical processing, receive input from both populations of afferents. First, we show that many cortical neurons have both a significant sustained response and a significant off response. Second, the strength of the off response is uncorrelated with that of the sustained response, which is to be expected if sustained and off responses stem from different populations of afferent fibers. Third, the bulk of the variance in cortical responses to step indentations can be accounted for using a linear combination of both SA1 and RA responses. Finally, we show that the off response in cortical neurons does not reflect rebound from inhibition. We conclude that the convergence of modality specific input onto individual neurons is common in primary somatosensory cortex and discuss how this conclusion might be reconciled with previous findings.

The representation of stimulus orientation in the early stages of somatosensory processing.

At an early stage of processing, a stimulus is represented as a set of contours. In the representation of form, a critical feature of these local contours is their orientation. In the present study, we investigate the representation of orientation at the somatosensory periphery and in primary somatosensory cortex. We record the responses of mechanoreceptive afferents and of neurons in areas 3b and 1 to oriented bars and edges using a variety of stimulus conditions. We find that orientation is not explicitly represented in the responses of single afferents, but a large proportion of orientation detectors (approximately 50%) can be found in areas 3b and 1. Many neurons in both areas exhibit orientation tuning that is preserved across modes of stimulus presentation (scanned vs indented) and is relatively insensitive to other stimulus parameters, such as amplitude and speed, and to the nature of the stimulus, bar or edge. Orientation-selective neurons tend to be more SA (slowly adapting)-like than RA (rapidly adapting)-like, and the strength of the orientation signal is strongest during the sustained portion of the response to a statically indented bar. The most orientation-selective neurons in SI are comparable in sensitivity with that measured in humans. Finally, responses of SI neurons to bars and edges can be modeled with a high degree of accuracy using Gaussian or Gabor filters. The similarity in the representations of orientation in the visual and somatosensory systems suggests that analogous neural mechanisms mediate early visual and tactile form processing.

A dense array stimulator to generate arbitrary spatio-temporal tactile stimuli.

The generation and presentation of tactile stimuli presents a unique challenge. Unlike vision and audition, in which standard equipment such as monitors and audio systems can be used for most experiments, tactile stimuli and/or stimulators often have to be tailor-made for a given study. Here, we present a novel tactile stimulator designed to present arbitrary spatio-temporal stimuli to the skin. The stimulator consists of 400 pins, arrayed over a 1cm(2) area, each under independent computer control. The dense array allows for an unprecedented number of stimuli to be presented within an experimental session (e.g., up to 1200 stimuli per minute) and for stimuli to be generated adaptively. The stimulator can be used in a variety of modes and can deliver indented and scanned patterns as well as stimuli defined by mathematical spatio-temporal functions (e.g., drifting sinusoids). We describe the hardware and software of the system, and discuss previous and prospective applications.

Spatiotemporal receptive fields of peripheral afferents and cortical area 3b and 1 neurons in the primate somatosensory system.

Neurons in area 3b have been previously characterized using linear spatial receptive fields with spatially separated excitatory and inhibitory regions. Here, we expand on this work by examining the relationship between excitation and inhibition along both spatial and temporal dimensions and comparing these properties across anatomical areas. To that end, we characterized the spatiotemporal receptive fields (STRFs) of 32 slowly adapting type 1 (SA1) and 21 rapidly adapting peripheral afferents and of 138 neurons in cortical areas 3b and 1 using identical random probe stimuli. STRFs of peripheral afferents consist of a rapidly appearing excitatory region followed by an in-field (replacing) inhibitory region. STRFs of SA1 afferents also exhibit flanking (surround) inhibition that can be attributed to skin mechanics. Cortical STRFs had longer time courses and greater inhibition compared with peripheral afferent STRFs, with less replacing inhibition in area 1 neurons compared with area 3b neurons. The greater inhibition observed in cortical STRFs point to the existence of underlying intracortical mechanisms. In addition, the shapes of excitatory and inhibitory lobes of both peripheral and cortical STRFs remained mostly stable over time, suggesting that their feature selectivity remains constant throughout the time course of the neural response. Finally, the gradual increase in the proportion of surround inhibition from the periphery to area 3b to area 1, and the concomitant decrease in response linearity of these neurons indicate the emergence of increasingly feature-specific response properties along the somatosensory pathway.