A national survey of caregiver's own experiences and perceptions of U.S. health care system when addressing their health and caring for an older adult.

BACKGROUND: Caregiving is a demanding role that can negatively impact a person's health and well-being. As such, adequate access to health care is important for maintaining the family caregiver's own personal health. The aims of this study were to identify if family caregivers of older adults had more difficulty accessing health care services than non-caregivers and to identify if family caregivers felt access to additional services would be beneficial for maintaining their own personal health care. METHODS: National survey of 3026 US adults aged 30 to 89 years old. Participants were grouped based on self-reported caregiving experience. Survey asked about access to care, importance of health care services and whether caregivers had support needed. Descriptive statistics were used to compare caregiver and non-caregiver's responses. Multivariate logistic regression model assessed correlates of caregivers not having the support they needed. RESULTS: Caregivers were older, female, lower educational attainment, lower income, had more multiple chronic health conditions and health condition or disability that impacts their daily life. Caregivers reported difficulty accessing mental health services, dental services, medications, and supportive services at home. Caregivers felt it was important to have care coordinator, long-term relationship with primary care provider and access to house calls, telemedicine, and medications delivered to the home. Age, ethnicity, chronic conditions and confidence in finances were factors influencing whether caregiver had support needed to provide assistance to older care recipient. CONCLUSION: Caregivers provide needed support and care to older adults while also needing support for themselves. Health care services delivered in the home were highly desirable to caregivers and could help them maintain their health and well-being.

Indicators of potential health-related social needs and the association with perceived health and well-being outcomes among community-dwelling medicare beneficiaries.

PURPOSE: Health-related social needs (HRSNs) can make older adults' more vulnerable and impact their health, well-being, and ability to age-in-place. The current study assessed the prevalence of potential HRSNs (pHRSNs) across several domains (e.g., transportation, social isolation) and explored the associations with health and well-being outcomes in a sample of Medicare beneficiaries. METHODS: Cross-sectional analyses were conducted with a representative sample of community-dwelling Medicare beneficiaries (N = 5758) from the 2012 National Health and Aging Trends Study. Binary indicators of pHRSNs were created for five domains: medical and utility financial needs (MUFN), housing, nutrition, social isolation, and transportation. Outcomes were depression/anxiety, self-rated health, meaning/satisfaction, perceived control/adaptability. Variables were weighted, and multivariate regression models assessed associations between pHRSN variables and outcomes, controlling for sociodemographics and health conditions. RESULTS: Of the estimated 32 million community-dwelling beneficiaries, approximately 13.3 million were positive for ≥ 1 pHRSN and 11.4 million for ≥ 2 pHRSNs. The prevalence by domain was 7% for housing, 8% for transportation, 12% for UMFN and nutrition, and 33% for social isolation. Each domain, except for housing, was significantly (p < .05) associated with at least two of the four outcomes, where being positive for a pHRSN was associated with greater depression/anxiety and poorer self-rated general health. CONCLUSIONS: Over 40% of Medicare beneficiaries had ≥ 1 pHRSN indicators, which means they are more vulnerable and that may limit their ability to age-in-place. Given the growing aging population, better measures and methods are needed to identify, monitor, and address HRSNs. For example, leveraging existing community-based services through coordinated care may be an effective strategy to address older adults' HRSNs.

"We just get paid for 12 hours a day, but we work 24": home health aide restrictions and work related stress.

BACKGROUND: Home-bound patients in New York State requiring long-term care services have seen significant changes to their benefits due to turmoil in the Managed Long Term Care (MLTC) market. While there has been research conducted regarding the effect of MLTC challenges on beneficiaries, the impact of MLTC regulatory changes on home health aides has not been explored. METHODS: Qualitative interviews were conducted with formal caregivers, defined as paid home health aides (HHAs) (n = 13) caring for patients in a home-based primary care program in the New York City metropolitan area. HHAs were asked about their satisfaction with the home based primary care program, their own job satisfaction, and whether HHA restrictions affect their work in any way. Interviews were audio-recorded, transcribed, and analyzed. RESULTS: Two main themes emerged: (1) Pay, benefits and hours worked and (2) Concerns about patient well-being afterhours. HHAs are working more hours than they are compensated for, experience wage stagnation and loss of benefits, and experience stress related to leaving frail clients alone after their shifts end. CONCLUSIONS: HHAs experience significant job-related stress when caring for frail elderly patients at home, which may have implications for both patient care and HHA turnover. As government bodies contemplate new policy directions for long-term care programs which rely on HHAs the impact of these changes on this vulnerable workforce must be considered.

Care Team Perspectives and Acceptance of Telehealth in Scaling a Home-Based Primary Care Program: Qualitative Study.

BACKGROUND: Novel and sustainable approaches to optimizing home-based primary care (HBPC) programs are needed to meet the medical needs of a growing number of homebound older adults in the United States. Telehealth may be a viable option for scaling HBPC programs. OBJECTIVE: The purpose of this qualitative study was to gain insight into the perspectives of HBPC staff regarding adopting telehealth technology to increase the reach of HBPC to more homebound patients. METHODS: We collected qualitative data from HBPC staff (ie, physicians, registered nurses, nurse practitioners, care managers, social workers, and medical coordinators) at a practice in the New York metropolitan area through 16 semistructured interviews and three focus groups. Data were analyzed thematically using the template analysis approach with Self-Determination Theory concepts (ie, relatedness, competence, and autonomy) as an analytical lens. RESULTS: Four broad themes-pros and cons of scaling, technology impact on staff autonomy, technology impact on competence in providing care, and technology impact on the patient-caregiver-provider relationship-and multiple second-level themes emerged from the analysis. Staff acknowledged the need to scale the program without diminishing effective patient-centered care. Participants perceived alerts generated from patients and caregivers using telehealth as potentially increasing burden and necessitating a rapid response from an already busy staff while increasing ambiguity. However, they also noted that telehealth could increase efficiency and enable more informed care provision. Telehealth could enhance the patient-provider relationship by enabling caregivers to be an integral part of the patient's care team. Staff members raised the concern that patients or caregivers might unnecessarily overutilize the technology, and that some home visits are more appropriate in person rather than via telehealth. CONCLUSIONS: These findings suggest the importance of considering the perspectives of medical professionals regarding telehealth adoption. A proactive approach exploring the benefits and concerns professionals perceive in the adoption of health technology within the HBPC program will hopefully facilitate the optimal integration of telehealth innovations.

Home and community-based services coordination for homebound older adults in home-based primary care.

BACKGROUND: Medically complex vulnerable older adults often face social challenges that affect compliance with their medical care plans, and thus require home and community-based services (HCBS). This study describes how non-medical social needs of homebound older adults are assessed and addressed within home-based primary care (HBPC) practices, and to identify barriers to coordinating HCBS for patients. METHODS: An online survey of members of the American Academy of Home Care Medicine (AAHCM) was conducted between March through November 2016 in the United States. A 56-item survey was developed to assess HBPC practice characteristics and how practices identify social needs and coordinate and evaluate HCBS. Data from 101 of the 150 surveys received were included in the analyses. Forty-four percent of respondents were physicians, 24% were nurse practitioners, and 32% were administrators or other HBPC team members. RESULTS: Nearly all practices (98%) assessed patient social needs, with 78% conducting an assessment during the intake visit, and 88% providing ongoing periodic assessments. Seventy-four percent indicated 'most' or 'all' of their patients needed HCBS in the past 12 months. The most common needs were personal care (84%) and medication adherence (40%), and caregiver support (38%). Of the 86% of practices reporting they coordinate HCBS, 91% followed-up with patients, 84% assisted with applications, and 83% made service referrals. Fifty-seven percent reported that coordination was 'difficult.' The most common barriers to coordinating HCBS included cost to patient (65%), and eligibility requirements (63%). Four of the five most frequently reported barriers were associated with practices reporting it was 'difficult' or 'very difficult' to coordinate HCBS (OR from 2.49 to 3.94, p-values < .05). CONCLUSIONS: Despite the barriers to addressing non-medical social needs, most HBPC practices provided some level of coordination of HCBS for their high-need, high-cost homebound patients. More efforts are needed to implement and scale care model partnerships between medical and non-medical service providers within HBPC practices.

Operation and challenges of home-based medical practices in the US: findings from six aggregated case studies.

BACKGROUND: Home-based primary care (HBPC) is a multidisciplinary, ongoing care strategy that can provide cost-effective, in-home treatment to meet the needs of the approximately four million homebound, medically complex seniors in the U.S. Because there is no single model of HBPC that can be adopted across all types of health organizations and U.S. geographic regions, we conducted a six-site HBPC practice assessment to better understand different operation structures, common challenges, and approaches to delivering HBPC. METHODS: Six practices varying in size, care team composition and location agreed to participate. At each site we conducted unstructured interviews with key informants and directly observed practices and procedures in the field and back office. RESULTS: The aggregated case studies revealed important issues focused on team composition, patient characteristics, use of technology and urgent care delivery. Common challenges across the practices included provider retention and unmet community demand for home-based care services. Most practices, regardless of size, faced challenges around using electronic medical records (EMRs) and scheduling systems not designed for use in a mobile practice. Although many practices offered urgent care, practices varied in the methods used to provide care including the use of community paramedics and telehealth technology. CONCLUSIONS: Learnings compiled from these observations can inform other HBPC practices as to potential best practices that can be implemented in an effort to improve efficiency and scalability of HBPC so that seniors with multiple chronic conditions can receive comprehensive primary care services in their homes.

Comparison of baseline-referenced versus norm-referenced analytical approaches for in-theatre assessment of mild traumatic brain injury neurocognitive impairment.

PRIMARY OBJECTIVE: To examine differences between the baseline-referenced and norm-referenced approaches for determining decrements in Automated Neuropsychological Assessment Metrics Version 4 TBI-MIL (ANAM) performance following mild traumatic brain injury (mTBI). RESEARCH DESIGN: ANAM data were reviewed for 616 US Service members, with 528 of this sample having experienced an mTBI and 88 were controls. METHODS AND PROCEDURES: Post-injury change scores were calculated for each sub-test: (1) normative change score = in-theater score - normative mean and (2) baseline change score = in-theater score - pre-deployment baseline. Reliable change cut-scores were applied to the change and the resulting frequency distributions were compared using McNemar tests. Receiver operator curves (ROC) using both samples (i.e. mTBI and control) were calculated for the change scores for each approach to determine the discriminate ability of the ANAM. MAIN OUTCOMES AND RESULTS: There were no statistical differences, p < 0.05 (Bonferonni-Holm corrected), between the approaches. When the area under the curve for the ROCs were averaged across sub-tests, there were no significant differences between either the norm-referenced (0.65) or baseline-referenced (0.66) approaches, p > 0.05. CONCLUSIONS: Overall, the findings suggest there is no clear advantage of using the baseline-referenced approach over norm-referenced approach.

Sensitivity of the Balance Error Scoring System and the Sensory Organization Test in the Combat Environment.

This study evaluated the utility of the Balance Error Scoring System (BESS) and the Sensory Organization Test (SOT) as tools for the screening and monitoring of Service members (SMs) with mild traumatic brain injury (mTBI) in a deployed setting during the acute and subacute phases of recovery. Patient records (N = 699) were reviewed for a cohort of SMs who sustained a blast-related mTBI while deployed to Afghanistan and were treated at the Concussion Restoration Care Center (CRCC) at Camp Leatherneck. On initial intake into the CRCC, participants completed two assessments of postural control, the BESS, and SOT. SMs with mTBI performed significantly worse on the BESS and SOT when compared with comparative samples. When the SOT data were further examined using sensory ratios, the results indicated that postural instability was primarily a result of vestibular and visual integration dysfunction (r > 0.62). The main finding of this study was that the sensitivity of the SOT composite score (50-58%) during the acute phase was higher than previous sensitivities found in the sports medicine literature for impact-related trauma.

Visual conflict and cognitive load modify postural responses to vibrotactile noise.

BACKGROUND: Underlying the increased incidence of falls during multitasking is a reduced ability to detect or attend to the sensory information signaling postural instability. Adding noise to a biological system has been shown to enhance the detection and transmission of weakened or sub-threshold cutaneous signals. If stochastic resonance is to become an effective adjunct to rehabilitation, we need to determine whether vibrotactile noise can be effective when added to an environment presenting with other sensory noise. METHODS: Sub-threshold vibration noise was applied for 30 sec at the soles of the feet in 21 healthy adults (20-29 yrs) between two 30-sec periods of no vibration. During the trials, subjects stood quietly with eyes closed or while viewing a visual scene that rotated in continuous upward pitch at 30 deg/sec. Subjects were also tested with these two visual conditions while performing a mental calculation task. It was hypothesized that sub-threshold vibration would increase regularity of postural sway, thereby improving postural stabilization during an attention demanding task but exerting less effect with multiple sensory demands. An ellipse fit to the covariance matrix revealed excursion of center of pressure (COP) and center of mass (COM) responses in the anterior-posterior and lateral planes. RMS values and approximate entropy of the COP and COM were calculated and statistically compared. RESULTS: The addition of vibrotactile noise to the plantar surface during quiet stance with eyes closed reduced the area of the COM and COP responses, which then returned to pre-vibration levels after vibration was removed. Postural sway was generally increased with both visual field rotations and mental calculation compared to the eyes closed condition. The effect of sub-threshold vibratory noise on postural behavior was modified when visual field rotations and mental calculation was combined. It was shown that the measure of approximate entropy reflected increased task complexity. CONCLUSIONS: Our results suggest that the impact of destabilizing signals is modulated when combined with vibrotactile stimulation. The strong aftereffects of the vibration stimulus suggest that the system has adapted to the sensory array even in the short time period tested here. The results imply that application of vibrotactile stimulation has the potential for diminishing sway magnitudes while increasing the potential for response variability, thereby presenting a non-invasive method of reducing the potential for falls.

Postural responses of adults with cerebral palsy to combined base of support and visual field rotation.

We employed a virtual environment to examine the postural behaviors of adults with cerebral palsy (CP). Four adults with CP (22-32 years) and nine healthy adults (21-27 years) were tested with a Rod and Frame protocol. They then stood quietly on a platform within a three-wall virtual environment. The platform was either kept stationary or tilted 3(°) into dorsiflexion in the dark or with pitch up and down visual field rotations at 30(°)/s and 45(°)/s. While the visual field rotated, the platform was held tilted for 30 s and then slowly returned to a neutral position over 30 s. Center of pressure (CoP) was recorded and center of mass (CoM) as well as trunk and ankle angles were calculated. Electromyography (EMG) responses of the ankle and the hip muscles were recorded and analyzed using wavelets. Larger angular deviations from vertical and horizontal in the Rod and Frame test indicated that adults with CP were more visually dependent than healthy adults. Adults with CP had difficulty maintaining balance when standing on a stationary platform during pitch upward rotation of the visual scene. When the platform was tilted during visual field rotations, adults with CP took longer to stabilize their posture and had larger CoM oscillations than when in the dark. The inability to compensate for busy visual environments could impede maintenance of functional locomotion in adults with CP. Employing a visual field stimulus for assessment and training of postural behaviors would be more meaningful than testing in the dark.

Reorientation to vertical modulated by combined support surface tilt and virtual visual flow in healthy elders and adults with stroke.

We explored how changes in visual attention impacted postural motor performance in healthy elders and adults post-stroke within a virtual reality environment, including when vestibular information was not perceptible. Visual dependence in 13 healthy (50-80 years) and 13 adults post-stroke (49-70 years) was assessed with a rod-and-frame task. Three degree support surface dorsiflexion tilts at 30°/s were combined with 30° and 45°/s continuous pitch rotations of the visual environment. The support surface remained tilted for 30 s followed by a 0.1°/s return to neutral during continued visual field rotation. Body displacement and ankle muscle responses were recorded, and wavelet transforms calculated. Muscle frequencies and kinematic measures were examined with functional principal component analysis, and weights compared through mixed model repeated measures ANOVA. Both populations exhibited increased backward sway with pitch upward visual field motion; adults post-stroke produced significantly larger muscle responses. Lateral sway was most regulated when visual flow velocity matched platform velocity. Visual flow summed with direction of support surface instability and visually dependent individuals produced more controlled lateral sway when viewing a dynamic visual field. Provoking postural instability within a dynamic visual flow field could serve as a training tool for postural stabilizing actions, particularly when visual dependence is exhibited.

Continuous visual field motion impacts the postural responses of older and younger women during and after support surface tilt.

The effect of continuous visual flow on the ability to regain and maintain postural orientation was examined. Fourteen young (20-39 years old) and 14 older women (60-79 years old) stood quietly during 3° (30°/s) dorsiflexion tilt of the support surface combined with 30° and 45°/s upward or downward pitch rotations of the visual field. The support surface was held tilted for 30 s and then returned to neutral over a 30-s period while the visual field continued to rotate. Segmental displacement and bilateral tibialis anterior and gastrocnemius muscle EMG responses were recorded. Continuous wavelet transforms were calculated for each muscle EMG response. An instantaneous mean frequency curve (IMNF) of muscle activity, center of mass (COM), center of pressure (COP), and angular excursion at the hip and ankle were used in a functional principal component analysis (fPCA). Functional component weights were calculated and compared with mixed model repeated measures ANOVAs. The fPCA revealed greatest mathematical differences in COM and COP responses between groups or conditions during the period that the platform transitioned from the sustained tilt to a return to neutral position. Muscle EMG responses differed most in the period following support surface tilt indicating that muscle activity increased to support stabilization against the visual flow. Older women exhibited significantly larger COM and COP responses in the direction of visual field motion and less muscle modulation when the platform returned to neutral than younger women. Results on a Rod and Frame test indicated that older women were significantly more visually dependent than the younger women. We concluded that a stiffer body combined with heightened visual sensitivity in older women critically interferes with their ability to counteract posturally destabilizing environments.

Time series analysis of postural responses to combined visual pitch and support surface tilt.

The purpose of using time-series analyses is to provide interpretation of information on curves or functions, such as dynamic, biomechanical data. We evaluated the application of one method of time-series analysis for assessing changes in postural responses when exposed to a continuously rotating visual field combined with a tilted support surface. Functional Principal Component Analysis (fPCA) was applied to center of mass (CoM) trajectories collected from 22 young adults (20-39 y.o.) on a fixed surface or following a 3 degree (30°/s) dorsiflexion tilt of the support surface combined with continuous upward or downward pitch rotation of the visual field at 30 and 45°/s. The usefulness of this analytical tool is that each curve is treated as a distinct observation by itself, allowing for traditional PCA to be applied to the analysis of curves. Results of the fPCA highlighted 5 distinct time periods in the CoM curves that explained 91% of the variability in the data. These periods in which the young adults altered their CoM in response to visual field motion would not have been identified if we had relied on the onset and offset of the transient disturbance to distinguish responses. Young adults significantly displaced their CoM in response to visual motion over both the period of support surface tilt and while the support surface returned to a neutral position. Our results indicate that fPCA is a viable method when applied to the small but complex changes that emerge in postural data and might allow for a better understanding of time dependent processes occurring with pathology and intervention.

Augmenting sensory-motor conflict promotes adaptation of postural behaviors in a virtual environment.

We present results from a series of studies that investigated how multimodal mismatches in a virtual environment modified postural response organization. Adaptation of motor commands to functional circumstances is driven directly by error signals. Thus, motor relearning should increase when performing in environments containing sensory mismatch. We hypothesized that kinematics of the response would be linked to specific characteristics of the sensory array. Sensory weighting was varied by: 1) rotating the visual field about the talo-crural joint or the interaural axis, 2) adding stochastic vibrations at the sole of the foot, and 3) combining galvanic vestibular stimulation with rotations of the visual field. Results indicated that postural responses are shaped by the location of a sensory disturbance and also by the processing demands of the environmental array. Sensory-motor demands need to be structured when developing therapeutic interventions for patients with balance disorders.

Influence of moving visual environment on sit-to-stand kinematics in children and adults.

The effect of visual field motion on the sit-to-stand kinematics of adults and children was investigated. Children (8 to12 years of age) and adults (21 to 49 years of age) were seated in a virtual environment that rotated in the pitch and roll directions. Participants stood up either (1) concurrent with onset of visual motion or (2) after an immersion period in the moving visual environment, and (3) without visual input. Angular velocities of the head with respect to the trunk, and trunk with respect to the environment, w ere calculated as was head andtrunk center of mass. Both adults and children reduced head and trunk angular velocity after immersion in the moving visual environment. Unlike adults, children demonstrated significant differences in displacement of the head center of mass during the immersion and concurrent trials when compared to trials without visual input. Results suggest a time-dependent effect of vision on sit-to-stand kinematics in adults, whereas children are influenced by the immediate presence or absence of vision.

Classifying subgroups of chronic low back pain patients based on lifting patterns.

OBJECTIVE: To compare self-reported measures of chronic lower back pain (CLBP) patients who were assigned to 2 subgroups based on their lifting patterns performed during a repetitive lifting task. DESIGN: Cross-sectional study. SETTING: Research laboratory PARTICIPANTS: CLBP subjects (n=81) and pain-free controls (n=53). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measures of lifting patterns and self-reported disability, pain, and psychosocial aspects. RESULTS: Two CLBP subgroups were found: 1 group that lifts similarly to control subjects (n=35) and 1 group that lifts very differently from controls (n=46). The CLBP group that lifted differently than controls reported higher pain intensity (P=.005), higher pain severity (P=.025), and lower self-efficacy (P=.013) than the CLBP group that lifted similarly to controls. CONCLUSIONS: A classification system based on lifting patterns identified 2 CLBP subgroups that were significantly different on lifting and self-reported measures, indicating the importance of physical functioning measures in classification systems.

The impact of chronic low back pain on older adults: a comparative study of patients and controls.

Chronic low back pain (CLBP) is one of the most common, poorly understood, and potentially disabling chronic pain conditions from which older adults suffer. Many older adults remain quite functional despite CLBP, and because age-related comorbidities often exist independently of pain (e.g., medical illnesses, sleep disturbance, mobility difficulty), the unique impact of CLBP is unknown. We conducted this research to identify the multidimensional factors that distinguish independent community dwelling older adults with CLBP from those that are pain-free. Three hundred twenty cognitively intact participants (162 with moderate pain for 3 months, and 158 pain-free) underwent comprehensive assessment of pain severity, medical comorbidity (illnesses, body mass index, medications), severity of degenerative disc and facet disease, lumbar flexion, psychological constructs (self-efficacy, mood, overall mental health), and self-reported as well as performance-based physical function. Significant differences were ascertained for all 22 measures. Discriminant function analysis revealed that eight measures uniquely maximized the separation between the two groups (self-reported function with the Functional Status Index and the SF-36, performance-based function with repetitive trunk rotation and functional reach, mood with the Geriatric Depression Scale, comorbidity with the Cumulative Illness Rating Scale and BMI, and severity of degenerative disc disease). These results should help to guide investigators that perform studies of CLBP in older adults and practitioners that want an easily adaptable battery for use in clinical settings.

The relationship between pain, neuropsychological performance, and physical function in community-dwelling older adults with chronic low back pain.

OBJECTIVE: Chronic pain and cognitive impairment are prevalent and disabling in older adults (OA), but their interrelationship has not been rigorously tested. We did so in OA with chronic low back pain (CLBP). DESIGN: A total of 323 OA (160 pain-free, 163 CLBP; mean age 73.5 years, 45% female) had neuropsychological (NP) testing with the Repeatable Battery for the Assessment of Neuropsychological Status, Trail Making Test, and the Grooved Pegboard Test. Pain intensity was measured with the McGill Pain Questionnaire Short Form. Physical performance (gait speed, functional reach, chair rise, trunk rotation, and static/dynamic lifting), psychosocial disruption (Geriatric Depression Scale, the Short Form-36 Mental Health and Role Limitations-Emotional Composite scale), and self-reported disability (Functional Status Index, the Short From-36 Physical Functioning/Role-Physical Composite scale) were also measured. SETTING: Outpatient research laboratory. RESULTS: There were no group differences in age, gender, or educational level, but significant differences in NP scores (P = 0.01) were found. Five scales accounted for the differences: immediate memory (P = 0.002), language (P = 0.004), delayed memory (P = 0.04), mental flexibility (Trails B [P = 0.02]), and Grooved Pegboard (P = 0.05). NP scores were significantly correlated with physical performance (R2= 0.30, P < 0.001), but not self-reported disability (R2= 0.04, P = 0.52) or psychosocial disruption (R2= 0.05, P = 0.46). NP function was correlated with pain intensity (R2= 0.17, P < 0.001), and NP function mediated the relationship between pain and physical performance. CONCLUSIONS: OA with CLBP demonstrated impaired NP performance as compared with pain-free OA. Further, pain severity was inversely correlated with NP performance, and NP performance mediated the relationship between pain and physical performance. Future research should examine whether cognitive function and impaired physical performance can be improved with pain reduction.

Evaluating reliability of hidden Markov models that describe the lifting patterns of chronic lower back pain patients and controls.

Two hidden Markov models (HMMs) were designed to identify sub-groups of chronic lower back pain (CLBP) subjects based on time series of lifting parameters obtained during a repetitive lifting task. Two simulation studies were conducted to determine the reliability of this approach, using data from the repetitive lifting study. The first simulation verifies that control and CLBP HMMs based on these data can reliably identify sequences that were generated from that model. The second simulation determines whether the HMMs can reliably identify sequences that are intentionally misclassified (CLBP lifting sequences included in the control group and visa versa). The kappa statistic is used to quantify reliability. The simulation results show that the HMMs provide a reliable technique to analyze time series of lifting patterns and can be used to identify misclassified subjects as a subgroup.