Mixed-Effects Variance Components Models for Biometric Family Analyses

Recent substantive research on biometric analyses of twin and family data has used both a biometric path analysis model (PAM) and a biometric variance components model (VCM). Methodological research on these same topics have suggested benefits of using linear structural equation model algorithms (SEMA) as well as mixed effect multilevel algorithms (MEMA). To better understand the potential similarities and differences among these approaches we first highlight the algebraic equivalence between the standard biometric PAM and the corresponding biometric VCM models for family data. Second, we demonstrate how several SEMA programs based on either the PAM or VCM approach produce equivalent estimates for all phenotypic and biometric parameters. Third, we show how the biometric VCM approach (but not the PAM approach) can be easily programmed using current MEMA programs (e.g., SAS PROC MIXED). We then expand the scope of these different approaches to include measured covariates, observed variable interactions and multiple relatives within each family. MEMA software is compared to SEMA software for programming complex models, including the flexibility of data input, treatment of missing data, inclusion of covariates, and ease of accommodating varying numbers of observations (per family or individual).     

儿童退缩和同伴关系的相关

目的：用元分析方法对近20年关于儿童退缩和同伴关系相关的研究结果进行总结。方法：用多水平分析技术对儿童退缩和同伴接受的相关、退缩和同伴拒绝相关的研究结果进行总结分析。结果：儿童退缩和同伴接受之间有显著的负相关关系，退缩和同伴拒绝之间有低度的非负相关关系，各研究结果之间的变异显著。结论：退缩导致儿童不良的同伴关系。     

Characterizing the fusion order and level-specific rates of arthrodesis in 3-level anterior cervical discectomy and fusion: A radiographic study

Pseudarthrosis is a well-recognized complication following multi-level ACDF. We aim to characterize the fusion order and level-specific rates of arthrodesis across four time points following 3-level ACDF. Patients who underwent 3-level ACDF by three UCSF spine surgeons from August 2012 to December 2019 were identified. Fusion status at each level was determined by measuring the interspinous motion on flexion and extension radiographs and assessing for evidence of bridging bone. Measurements were performed post-operatively at 6 weeks, 6 months, 12 months, and 18–24 months. A total of 77 patients with 3-level ACDF were identified and included in this study. Specific ACDF levels include C3-C6 (17 patients), C4-C7 (57 patients), and C5-T1 (3 patients). At 6 months, the cranial, middle, and caudal level fusion rates were 17.0%, 34.0%, and 3.8%, respectively. By 24 months, fusion rates were 61.1%, 88.9%, and 27.8% at the cranial, middle, and caudal level, respectively. PEEK cages were associated with lower odds of multi-level arthrodesis. Arthrodesis occurred the quickest at the middle level with an 88.9% fusion rate by 24 months after surgery. The caudal level had the slowest rate of arthrodesis with only a 27.8% fusion rate at 24 months, likely due to increased biomechanical stress at the most caudal level. Allograft was associated with higher odds of multi-level arthrodesis compared to PEEK cages.     

多发颈椎不连综合征的影像学特点与外科诊疗策略

【摘要】 目的：分析多发颈椎不连综合征（multilevel cervical disconnection syndrome,MCDS）的影像学特点及外科诊疗策略。方法：2004年3月~2021年6月,我院收治MCDS患者共7例,男性3例,女性4例;年龄5~46岁（中位年龄12岁）。7例MCDS患者中,平均椎体发育不良节段数3.6±1.3个节段,平均椎弓不连节段数5.7±1.5个节段,局部后凸角平均-92.2°±20.2°,C2-7 Cobb角平均-68.6°±31.0°,T1倾斜角（T1 slope,T1S）平均-12.5°±12.5°,后凸顶点位于C4节段1例,C5节段5例,T1节段1例;术前改良日本骨科学会评分（mJOA评分）8.5~14分（平均12.6±2.1分）,其中1例患者伴有吞咽困难。记录患者预矫形方式及手术方式,入院时、预矫形后、术后及末次随访影像学参数,神经功能及并发症。结果：1例术前接受颅骨牵引,3例接受平衡悬吊牵引,3例接受联合牵引,经术前牵引预矫形后,局部后凸角矫正率为60.8%。1例接受手术松解、Halo-vest外固定治疗,1例接受前路矫形内固定手术,1例接受后路矫形固定融合术,4例接受前-后联合手术治疗,手术固定6.0±2.1个节段,2例患者出现术后神经系统并发症,接受翻修手术。术后随访时间6~84个月（41.2±32.0个月）,末次随访局部后凸角平均-27.9°±11.6°,矫正率69.7%,C2-7 Cobb角平均-13.3°±28.4°,T1S平均4.9°±17.9°;术后mJOA评分10.5~17分（15.7±2.3分）,改善率78.3%。对比手术前后临床及影像学指标,mJOA评分、C2-7后凸角、局部后凸角及T1S有统计学差异。结论：MCDS影像学上主要表现为前方椎体发育不良伴多节段椎弓不连,继发严重后凸畸形。治疗策略可采取术前牵引预矫形并前路多节段椎体切除重建、后路长节段固定融合。     

3D打印个体化人工椎体在多节段脊柱肿瘤切除后脊柱稳定性重建中的应用

目的:探讨3D打印个体化人工椎体在多节段脊柱肿瘤切除后脊柱稳定性重建中应用的安全性和有效性。方法:回顾性分析2017年5月～2019年12月在我院行多节段脊柱肿瘤全切并行3D打印人工椎体脊柱稳定性重建的患者9例,其中男性3例,女性6例;年龄25～64岁,平均41.7±10.5岁,随访18.3±11.4个月(6～36个月)。9例均为原发肿瘤:T5～T7骨母细胞瘤术后复发1例,T7～T8上皮样血管肉瘤1例,T10～T11未分化小圆细胞肉瘤1例,T11～L1软骨肉瘤1例,骨巨细胞瘤5例(T6～T8共2例,T2～T3、T4～T5、T11～L1各1例)。依据肿瘤位置及周围软组织侵袭程度,采取单纯后路手术方式8例,前后路联合手术方式1例行多节段全椎体切除,并通过激光选区融化技术构建个体化3D打印人工椎体进行脊柱稳定性重建。记录手术时间、出血量,通过术后X线片(1个月、3个月、6个月、12个月)及CT(6个月、12个月、24个月)定期复查,之后每6个月复查1次。应用BrantiganSteffee脊柱融合分级评估人工椎体稳定性、界面骨融合情况,手术前及术后1周进行Frankel神经功能评分及疼痛视觉模拟(visual analogue scale,VAS)评分。术后定期观察肿瘤是否复发生原位复发、远处转移以及患者生存情况。结果:所有患者均成功接受多节段脊柱肿瘤切除3D打印人工椎体脊柱稳定性重建术,其中2个节段椎体切除4例,3个节段椎体切除5例。患者手术时间433.3±174.6min(235～740min),术中出血量4816.7±3221.2ml(1000～14000ml)。术前的VAS评分4.1±1.1分,术后7d患者的VAS评分1.2±0.4分,差异具有统计学意义(P0.001)。术前Frankel分级为D级的3例患者术后7d时有2例恢复到E级,1例无明显变化,6例E级患者无明显变化。随访期内3D打印人工椎体与邻近椎体匹配情况良好,无松动、下沉及移位,同时未出现断钉、断棒等内固定失败情况。术后6个月,人工椎体与邻近椎体接触紧密,开始出现界面骨长入,术后12个月,人工椎体与邻近椎体出现骨性连接,发生骨性融合。随访期内7例患者无肿瘤复发转移,1例软骨肉瘤患者术后16个月局部复发,安罗替尼治疗后肿瘤无恶化,1例上皮样血管肉瘤患者全身多发转移于术后18个月死亡,患者中位生存期18个月。结论:3D打印个体化人工椎体可以满足多节段脊柱肿瘤切除后脊柱稳定性重建的要求,精确恢复椎体连续性,精准匹配相邻椎体,自身孔隙结构利于骨的长入,是一种多节段脊柱肿瘤切除后理想的脊柱稳定性重建方法。     

单纯前路与前后联合入路治疗退变性多节段脊髓型颈椎病的对比研究

目的 比较前路多节段（≥3）颈椎间盘切除椎管减压植骨融合内固定（ACDF）与后路单开门椎管扩大成形（ELAP）联合ACDF治疗伴颈椎后凸、巨大椎间盘突出的退变性多节段脊髓型颈椎病的疗效。方法 回顾性分析2014年1月至2019年1月于我院接受多节段ACDF或ELAP联合ACDF治疗的41例合并颈椎后凸畸形、巨大椎间盘突出的退变性多节段脊髓型颈椎病病人的临床资料,根据手术方式分为单纯前路组（21例）和前后联合入路组（20例）,单纯前路组21例,男10例,女11例,年龄为（52.10±5.96）岁。前后联合入路组20例,男12例,女8例,年龄为（53.23±5.12）岁。记录病人手术时间、术中出血量、住院时间、疼痛视觉模拟量表（visual analogue scale,VAS）评分、日本骨科协会（Japanese Orthopedic Association,JOA）评分、Nurick评分、C_2-7 Cobb角、局部后凸角（RK）、C_2-7矢状面垂直轴（SVA）。结果 前后联合入路组手术时间、出血量大于单纯前路组（P＜0.05）。两组住院时间的差异无统计学意义（P＞0.05）。末次随访,两组VAS评分、Nurick评分均小于术前,JOA评分大于术前,差异均有统计学意义（P＜0.05）;前后联合入路组VAS评分、Nurick评分小于单纯前路组,JOA评分、JOA改善率大于单纯前路组,差异均有统计学意义（P＜0.05）。两组C_2-7 Cobb角、RK均大于术前（P＜0.05）,C_2-7 SVA与术前比较,差异无统计学意义（P＞0.05）。两组C_2-7 Cobb角、RK、C_2-7 SVA比较,差异无统计学意义（P＞0.05）。结论 多节段ACDF、ELAP联合ACDF治疗合并颈椎后凸畸形、巨大椎间盘突出的退变性多节段脊髓型颈椎病均可显著改善病人的临床症状及颈椎曲度。与多节段ACDF比较,ELAP联合ACDF虽然手术创伤大但术式更安全,病人的临床症状效果改善更好。     

The Multilevel Structure of Four Adolescent Problems

This paper examines variability in adolescent self-reported behavior at the individual, cohort, and school levels for 8th and 11th graders. We examine four adolescent behaviors: substance use, antisocial behavior, depression, and academic performance. Research staff collected the data as part of the Oregon Healthy Teens survey of a population-based sample of 60,837 adolescents over three years in 92 communities. The results indicate that schools vary over time, but not necessarily systematically, and grade-level cohorts account for important variance within schools. The school and cohort combined, however, accounted for at most 4% of the overall variance. The results have implications for research and practice in schools and communities. For example, selection of communities for interventions based on high levels of adolescent problems may be unproductive if individuals account for at least 96% of the variance. Furthermore, in non-experimental designs, cohort variability, not an intervention, may account for apparent improvement across     

Utilization of care during pregnancy in rural Guatemala: does obstetrical need matter?

This study examines factors associated with the use of biomedical care during pregnancy in Guatemala, focusing on the extent to which complications in an ongoing or previous pregnancy affect a woman's decisions to seek care. The findings, based on multilevel models, suggest that obstetrical need, as well as demographic, social, and cultural factors, are important predictors of pregnancy care. In contrast, measures of availability and access to health services have modest effects. The results also suggest the importance of unobserved variables–such as quality of care–in explaining women's decisions about pregnancy care. These results imply that improving proximity to biomedical services is unlikely to have a dramatic impact on utilization in the absence of additional changes that improve the quality of care or reduce barriers to access. Moreover, current efforts aimed at incorporating midwives into the formal health-care system may need to extend their focus beyond the modification of midwife practices to consider the provision of culturally appropriate, high-quality services by traditional and biomedical providers alike.     

Do stand-alone interbody spacers with integrated screws provide adequate segmental stability for multilevel cervical arthrodesis?

Background contextSome postoperative complications after anterior cervical fusions have been attributed to anterior cervical plate (ACP) profiles and the necessary wide operative exposure for their insertion. Consequently, low-profile stand-alone interbody spacers with integrated screws (SIS) have been developed. Although SIS constructs have demonstrated similar biomechanical stability to the ACP in single-level fusions, their role as a stand-alone device in multilevel reconstructions has not been thoroughly evaluated.PurposeTo evaluate the acute segmental stability afforded by an SIS device compared with the traditional ACP in the setting of a multilevel cervical arthrodesis.Study designIn vitro human cadaveric biomechanical analysis.MethodsThirteen human cadaveric cervical spines (C2–T1) were nondestructively tested with a custom 6 df spine simulator under axial rotation, flexion-extension, and lateral bending loading. After intact analysis, eight single-levels (C4–C5/C6–C7) from four specimens were instrumented and tested with ACP and SIS. Nine specimens were tested with C5–C7 SIS, C5–C7 ACP, C4–C7 ACP, C4–C7 ACP+posterior fixation, C4–C7 SIS, and C4–C7 SIS+posterior fixation. Testing order was randomized with each additional level instrumented. Full range of motion (ROM) data were obtained and analyzed by each loading modality, using mean comparisons with repeated measures analysis of variance. Paired t tests were used for post hoc analysis with Sidak correction for multiple comparisons.ResultsNo significant difference in ROM was noted between the ACP and SIS for single-level fixation (p>.05). For multisegment reconstructions (two and three levels), the ACP proved superior to SIS and intact condition, with significantly lower ROM in all planes (p<.05). When either the three-level SIS or ACP constructs were supplemented with posterior lateral mass fixation, there was a greater than 80% reduction in ROM under all testing modalities (p<.05), with no significant difference between the ACP and SIS constructs (p>.05).ConclusionsThe SIS device may be a reasonable option as a stand-alone device for single-level fixation. However, SIS devices should be used with careful consideration in the setting of multilevel cervical fusion. However, when supplemented with posterior fixation, SIS devices are a sound biomechanical alternative to ACP for multilevel fusion constructs.     

Trajectories of Substance Use among Child Welfare-Involved Youth: Longitudinal Associations with Child Maltreatment History and Emotional/Behavior Problems

Background: Maltreated children experience a variety of adverse outcomes including substance use problems. Although previous research indicated that there may be distinct trajectories of substance use among these youth, studies have examined them as if they were a single homogeneous group. Objectives: The goals of this study were to explore substance use trajectories among child welfare-involved youth and to identify characteristics that distinguish substance use trajectories. Methods: Data from the National Survey of Child and Adolescent Well-Being (NSCAW II) were used. Multilevel latent growth mixture modeling (MLGMM) was performed using a subsample of 625 youth from ages 11–17 years investigated for maltreatment in 2008–2009. Measures included self-reported use of substance use during the previous 30 days, demographic characteristics, maltreatment history, placement in out-of-home care, and behavioral health problems. Results: MLGMM identified two distinct substance use trajectory classes including High Stable Substance Use and Rapid Progression Use. Findings suggest that the experience of physical abuse is the key factor that distinguishes the two groups. When the effects of class-specific covariates were examined, results suggest that involvement in substance use behavior and its escalation vary between groups and are affected by youth’s different previous experiences. Conclusions/Importance: The results have important implications for understanding individual differences in substance use behavior over time and how these differences were shaped by youth’s experiences of family adversity. Study findings may be helpful for developing and enhancing the effectiveness of interventions targeted at decreasing substance use behaviors in child welfare-involved youth.