Unsupervised Classification During Time-Series Model Building

Researchers who collect multivariate time-series data across individuals must decide whether to model the dynamic processes at the individual level or at the group level. A recent innovation, group iterative multiple model estimation (GIMME), offers one solution to this dichotomy by identifying group-level time-series models in a data-driven manner while also reliably recovering individual-level patterns of dynamic effects. GIMME is unique in that it does not assume homogeneity in processes across individuals in terms of the patterns or weights of temporal effects. However, it can be difficult to make inferences from the nuances in varied individual-level patterns. The present article introduces an algorithm that arrives at subgroups of individuals that have similar dynamic models. Importantly, the researcher does not need to decide the number of subgroups. The final models contain reliable group-, subgroup-, and individual-level patterns that enable generalizable inferences, subgroups of individuals with shared model features, and individual-level patterns and estimates. We show that integrating community detection into the GIMME algorithm improves upon current standards in two important ways: (1) providing reliable classification and (2) increasing the reliability in the recovery of individual-level effects. We demonstrate this method on functional MRI from a sample of former American football players.     

Positive effects of low intensity recorded maternal voice on physiologic reactions in premature infants

ObjectiveTo evaluate the effect of low intensity recorded maternal voice on the physiologic reactions of healthy premature infants in the neonatal intensive care unit (NICU).MethodsPhysiologic responses of 20 healthy preterm infants in the NICU of Shariati Hospital, Tehran, were obtained during a 15 min intervention including three 5 min periods (no-sound control, audio recorded playback of mother’s voice, no-sound post-voice). The intervention was presented three times a day for three consecutive days. During each intervention, oxygen saturation (%, OSPR), heart rate (HR), and respiratory rate (RR) were recorded at 1 min intervals over the 15 min and then averaged over each 5 min period, resulting in 3 averages for each variable for each intervention.ResultsRepeated Measures Analysis of Variance were employed to examine each variable separately. Over the three days, comparison of oxygen saturation over each of the three periods (before, during voice, after) revealed an increase in oxygen saturation during the voice period, compared to the pre-voice period, which persisted over the post-voice period; there were no differences between the voice and post-voice periods. Analyses of the HR and RR data showed a decrease in both variables during the voice period compared to the pre-voice period which persisted over the post-voice period. Again, there were no differences between the voice and post-voice periods.ConclusionExposure to low intensity recorded maternal voice has positive effects on the preterm infants ‘physiologic responses.     

Person‐specific versus multilevel autoregressive models: Accuracy in parameter estimates at the population and individual levels

This paper compares the multilevel modelling (MLM) approach and the person‐specific (PS) modelling approach in examining autoregressive (AR) relations with intensive longitudinal data. Two simulation studies are conducted to examine the influences of sample heterogeneity, time series length, sample size, and distribution of individual level AR coefficients on the accuracy of AR estimates, both at the population level and at the individual level. It is found that MLM generally outperforms the PS approach under two conditions: when the sample has a homogeneous AR pattern, namely, when all individuals in the sample are characterized by AR processes with the same order; and when the sample has heterogeneous AR patterns, but a multilevel model with a sufficiently high order (i.e., an order equal to or higher than the maximum order of individual AR patterns in the sample) is fitted and successfully converges. If a lower‐order multilevel model is chosen for heterogeneous samples, the higher‐order lagged effects are misrepresented, resulting in bias at the population level and larger prediction errors at the individual level. In these cases, the PS approach is preferable, given sufficient measurement occasions (T ≥ 50). In addition, sample size and distribution of individual level AR coefficients do not have a large impact on the results. Implications of these findings on model selection and research design are discussed.     

ICU向患者家属开放的理论研究

ICU实行的基本是封闭式管理,这不仅带来了一些伦理问题,也容易引发医疗纠纷,从伦理学的需要、预防医疗纠纷、改善医患关系等方面探讨ICU向患者家属开放的必要性,分析开放存在的问题,论证了ICU向患者家属开放的可行性。     

新生儿重症监护室中放弃治疗的伦理问题

对于新生儿重症监护室中的一部分危重新生儿,虽然可以借助高新尖的医疗技术挽留他们的性命,但却不能避免其出现影响远期生存质量的后遗症。因此患儿家属和医务人员陷入了是否对这些危重新生儿实施放弃治疗的两难困境。对NICU中放弃治疗的对象、伦理学依据、伦理学意义以及如何实施放弃治疗的问题加以讨论,为NICU医务人员提供有益参考。     

An Intensive Outpatient Program for Veterans With Posttraumatic Stress Disorder and Traumatic Brain Injury

Post-9/11 service members may return from military service with a complicated set of symptoms and conditions, such as posttraumatic stress disorder (PTSD), depression, substance misuse, and traumatic brain injury (TBI), that interfere with reintegration and impair functioning. Although evidence-based treatments that facilitate recovery exist, their successful delivery at a sufficient dose is limited. Barriers to accessing treatment combined with challenges compiling a comprehensive treatment team further delay delivery of effective evidence-based care for PTSD, TBI, and co-occurring mental health conditions. This paper describes the development of a comprehensive, multidisciplinary, 2-week intensive day program for post-9/11 veterans with complex mental health concerns. The treatment program combines skill building groups, family education, and integrative health approaches with evidence-based individual PTSD or TBI care. Initial results from the first 132 participants were notable for a 97% completion rate, as well as statistically significant and clinically meaningful reductions in PTSD, neurobehavioral, and depression symptom severity for the 107 veterans who completed the PTSD track and the 21 who completed the TBI track. These data suggest the intensive program approach is an effective, well-tolerated model of treatment for post-9/11 veterans with PTSD and/or TBI. Future controlled studies should examine the effectiveness of this intensive model compared to standard evidence-based therapy delivery, as well as longitudinal outcomes.     

A one-step method for modelling longitudinal data with differential equations

Differential equation models are frequently used to describe non-linear trajectories of longitudinal data. This study proposes a new approach to estimate the parameters in differential equation models. Instead of estimating derivatives from the observed data first and then fitting a differential equation to the derivatives, our new approach directly fits the analytic solution of a differential equation to the observed data, and therefore simplifies the procedure and avoids bias from derivative estimations. A simulation study indicates that the analytic solutions of differential equations (ASDE) approach obtains unbiased estimates of parameters and their standard errors. Compared with other approaches that estimate derivatives first, ASDE has smaller standard error, larger statistical power and accurate Type I error. Although ASDE obtains biased estimation when the system has sudden phase change, the bias is not serious and a solution is also provided to solve the phase problem. The ASDE method is illustrated and applied to a two-week study on consumers’ shopping behaviour after a sale promotion, and to a set of public data tracking participants’ grammatical facial expression in sign language. R codes for ASDE, recommendations for sample size and starting values are provided. Limitations and several possible expansions of ASDE are also discussed.     

居民门诊费用现状及控制策略研究

近年来,各级政府和卫生部门均在采取措施控制医疗费用的不合理增长,但我国的医疗费用仍然呈上升趋势。门诊费用是医疗费用的重要组成部分,其上升幅度虽然有所下降,但仍高于城乡居民人均收入的增长幅度和同期的物价上涨幅度,对门诊费用的现状及控制策略进行研究,将有助于更有效地解决贫困人群看病难、看病贵问题。     

镇静与镇痛在ICU机械通气患者中的应用变化

探讨ICU内机械通气患者应用镇痛剂、镇静剂及肌松剂的情况及其对机械通气和预后的影响。回顾性分析我院中心ICU2006年、2007年收治的244例行有创机械通气治疗超过48h患者的临床资料,并将患者分为2006年组和2007年纽,用统计软件分析患者在年龄、性别、入ICU时APACHEⅡ评分、血糖、血浆白蛋白、基础疾病,气管插管时间、机械通气时间、ICU住院天数、镇痛与镇静剂应用的时间、机械通气时是否使用肌松剂、Ramsay评分及病死率方面是否存在差别。统计分析显示2006年组和2007年组在年龄、性剐、入ICU时APACHEⅡ评分、血糖、血浆白蛋白、是否使用肌松剂及基础疾病方面无差别;与2006年组相比2007年组患者气管插管时间、机械通气时间及ICU住院天数均缩短,镇痛与镇静剂应用时间均缩短,Ramsay评分降低,病死率下降。提示对机械通气的危重症患者应合理使用镇痛剂与镇静剂。     

儿科重症监护室中放弃治疗的相关问题研究

随着现代伦理学、生命质量和生命价值理论的发展,对于儿科重症监护室中部分病情危重且不可避免地将出现影响其远期生存质量的后遗症的患儿来说,选择放弃治疗可能更符合伦理学及患儿的最佳利益。对儿科重症监护室中部分患儿放弃治疗的实施过程、必备条件、常见原因、实施对象、相关伦理学及法律问题进行了探讨,以求为临床诊疗提供理论参考。