Outcomes at 3 Months of a Place and Active Hold Method of Flexor Tendon Rehabilitation Following Zone II Injury

Background: Previous studies have shown that outcomes following a place and active hold (PAH) are better than a passive flexion protocol after a two-strand core-suture repair of flexor tendons injuries in zone II. This study aims to determine the outcomes of a PAH protocol of flexor tendon rehabilitation following a four-strand core-suture plus an epitendinous suture repair of the flexor digitorum profundus (FDP) combined with a simple horizontal loop repair of the flexor digitorum superficialis (FDS). Methods: This is a prospective study of patients with complete injury to both flexor tendons in zone II. All tendons were repaired with a simple horizontal loop for FDS and four-strand core-suture plus epitendinous suture for FDP. The PAH protocol was used postoperatively for 6 weeks. The outcome was evaluated using flexion contracture and total active motion (TAM), interpreted using Strickland criteria and categorised as excellent, good, fair and poor at 6 weeks and 3 months. The linear regression model was used to determine predictors of outcomes. Results: The study included 32 patients with flexor tendon injury in 46 fingers. No repairs ruptured, and 24 (52%) digits achieved good or excellent motion 6 weeks after surgery using the Strickland criteria. According to the Strickland criteria, 41 (89%) digits ranked as excellent and good with no poor result at a 3-month follow-up. Four patients had 5-10° of flexion contracture. Age was the predictor of TAM at 6 weeks and accounted for 13% of its variation. Improvement of TAM from 6 weeks to 3 months was related to age and flexion contracture at 6 weeks. Conclusions: The PAH protocol can be considered a safe technique for flexor rehabilitation after four-strand core-suture repair of FDP in zone II. Level of Evidence: Level IV (Therapeutic).

Frictions and taxpayer responses: evidence from bunching at personal tax thresholds

We exploit kinks and notches in the UK personal tax schedule over a 40-year period to investigate how taxpayers respond to income tax and social security contributions. At kinks, where the marginal rate rises, we find bunching by company owner-managers and the self-employed, but not those with only employment income. Responses to notches, where the average rate rises, provide compelling evidence that this is because most employees face substantial frictions: fewer than a quarter bunch even where doing so would increase both consumption and leisure. We develop a new approach for identifying selection in who responds and for decomposing responses into hours and wage components. We find that those employees who do bunch at notches are almost exclusively part-time workers, but tend to have lower wages and work more hours than those part-time workers who do not bunch.

Rebates as incentives: The effects of a gym membership reimbursement program

A rich experimental literature demonstrates positive effects of pay-per-visit fitness incentives. However, most insurance plans that provide fitness incentives follow a different structure, offering membership reimbursements conditional on meeting a specific attendance threshold. We provide the first evidence in the literature on gym incentives of this structure, exploiting the introduction and subsequent discontinuation of a large-scale wellness program at a major American university. Our analysis leverages individual-level administrative data on gym attendance for the universe of students over a five-year period: the three years that the policy was in place, one year before implementation, and one year after termination. This provides us with 100,000 student-year observations and 1.5 million gym visits. Using bunching methods and difference-in-difference designs, we provide four empirical results. First, we document that the policy led to significant bunching at the attendance threshold. Second, we show that the program increased average gym visits by almost five visits per semester, a 20% increase from the mean. Third, we find that the policy not only motivated students who were previously near the threshold, but rather increased attendance across the entire visit distribution. Finally, we show that approximately 50% of the effect persists a year after program termination. Taken together, these results suggest that rebate-framed incentives with a high attendance threshold can induce healthy behaviors in the short-term, and that these positive behaviors persist even after the incentives have been removed.

Assessing blue wildebeests' vigilance, grouping and foraging responses to perceived predation risk using playback experiments

Two aspects of reactive antipredator behaviour are still unclear for ungulates. First, when there is a direct predation threat, how do prey balance antipredator and social vigilance to learn a predator's location and assess the risk? Second, how do an individual's group and environment affect its responses? We tested the responses of adult females in 101 groups of wildebeest to playbacks of lion roars or car noises in Etosha National Park, Namibia. We analysed how the times they spent in different types categories of vigilance, and their within-group density, were affected by the playbacks and how a range of social and environmental variables affected those responses. Females increased their antipredator vigilance but not their social vigilance, after lion roars but not car noises, suggesting that they mostly relied on their own vigilance rather than social information to try to find the source of the lion roars. Females' antipredator vigilance increased more when they were further from cover and with other prey species, suggesting that both circumstances increased their perception of risk. They 'bunched' more after lion roars than car noises and their bite rates decreased as they bunched. Animals' use of social information about threats is likely to be context-dependent.

Payment systems and hospital length of stay: a bunching-based evidence

Despite the huge attention on the long average hospital length of stay (LOS) in Japan, there are limited empirical studies on the impacts of the payment systems on LOS. In order to shed new light on this issue, we focus on the fact that reimbursement for hospital care is linked to the number of patient bed-days, where a "day" is defined as the period from one midnight to the next. This "midnight-to-midnight" definition may incentivize health care providers to manipulate hospital acceptance times in emergency patients, as patients admitted before midnight would have an additional day for reimbursement when compared with those admitted after midnight. We test this hypothesis using administrative data of emergency transportations in Japan from 2008 to 2011 (N = 2,146,498). The results indicate that there is a significant bunching in the number of acceptances at the emergency hospital around midnight; the number heaps a few minutes before midnight, but suddenly drops just after midnight. Given that the occurrence of emergency episode is random and the density is smooth during nighttime, bunching in the number of hospital acceptances around midnight suggests that hospital care providers shift the hospital acceptance times forward by hurrying-up to accept the patients. This manipulation clearly leads to longer LOS by one bed-day. In addition, the manipulation is observed in the prefectures where private hospitals mainly provide emergency medical services, suggesting hospital ownership is associated with the manipulation of hospital acceptance time.

Bunching at the kink: implications for spending responses to health insurance contracts

A large literature in empirical public finance relies on "bunching" to identify a behavioral response to non-linear incentives and to translate this response into an economic object to be used counterfactually. We conduct this type of analysis in the context of prescription drug insurance for the elderly in Medicare Part D, where a kink in the individual's budget set generates substantial bunching in annual drug expenditure around the famous "donut hole". We show that different alternative economic models can match the basic bunching pattern, but have very different quantitative implications for the counterfactual spending response to alternative insurance contracts. These findings illustrate the importance of modeling choices in mapping a compelling reduced form pattern into an economic object of interest.