Study design. This secondary data analysis included participants (n=101) who completed the SCOR kyphosis intervention in a randomized controlled waitlist design trial.10 We calculated a baseline Short Physical Performance Battery (SPPB) score using baseline measurements to divide the SCOR cohort into a low functioning group (LFG) and a high functioning group (HFG). The SPPB is a lower extremity strength, mobility and balance physical performance measure, and a composite measure of gait speed, Five-times Sit to Stand and ability to stand with feet together, feet in half tandem and feet in full tandem for 10 seconds.19 Each component is scored on an ordinal scale from 0 to 4, where 0 represents lowest ability and 4 represents highest ability, with a maximum score of 12 possible. The SPPB is predictive of future mobility decline and incident activities of daily living disability.19-21 The definition of low physical function was operationalized by an established cut-off score of 10 or less on the SPPB that identifies older adults who are at-risk for mobility decline.20,22 A score of 10 or less has been identified as the best cut-off point for the determination of the physical frailty process with a likelihood radio of 1.59.20,22 An SPPB score of 11 or 12 was categorized as the HFG. The SPPB has high levels of reliability, good to moderate concurrent validity with quality of life, strength, muscle power and mobility and scores less than 10 are predictive of all-cause mortality.23,24
Study participants. Participants in the original SCOR trial (n=112) were recruited from a university-based medical center and an integrated managed-care center in San Francisco from January 2013 to June 2015 and included community-dwelling adults age 60 or greater with hyperkyphosis > 40 degrees, English language proficient, able to walk 1 block without an assistive device and rise from a chair without their hands.10 Participants were excluded from the SCOR trial if they were unable to actively extend their thoracic spine by at least 5 degrees or had cognitive impairment.25 Participants were initially randomized to an active (n=57) or waitlist control (n=55) group, however 9 withdrew within the first week due to lack of time or interest, and 2 did not have analyzable baseline radiographs for Cobb angle measurements. Participants (n=101) who completed the trial were included in the secondary analysis. The trial protocol was approved by the Institutional Review Boards at the University of California, San Francisco and Kaiser Permanente Northern California. Written informed consent was obtained from all participants. The study protocol and methods were performed in accordance with the guidelines and regulations of the Declaration of Helsinki.
Intervention groups. The SCOR active intervention was a physical therapist led group targeted kyphosis exercise and posture training program for 1-hour twice weekly for 3 months.10 The active intervention included progressive high-intensity spinal and lower extremity strengthening exercise, thoracic spine and lower extremity range of motion exercise, and posture training. Participants were asked to practice good posture during activities of daily living outside the intervention and provided with an educational handout with pictures to reinforce good posture during activities of daily living. Details on the exercise and posture training intervention have been previously published.26 A wait-list control group received usual care during the initial 3-months and received the active intervention after the 3-month waitlist period, thus all participants received the intervention.
Demographic and other measures. Prior to randomization in the original SCOR trial, participants provided demographic and health information via self-report (age, sex, education, co-morbidities). Height and weight were collected using standard measures, and body mass index was calculated. Bone mineral density of the hip and spine was measured using dual-energy X-ray absorptiometry (GE Lunar Prodigy). Baseline standing lateral spine radiographs were obtained and assessed for prevalent vertebral fractures and and diffuse idiopathy skeletal hyperostosis by experienced assessors.27-29
Outcome Measures. SCOR study outcome measures were performed at baseline, 3-months and 6-months (for the waitlist group only). The waitlist group received the intervention after the 3-month measurement. All measurements were performed by trained examiners blinded to group allocation.
Physical Function. Performance-based physical function was assessed using the modified Physical Performance Test , 4-meter walk test, Timed Up and Go and Six-minute Walk tests.30-32 The modified Physical Performance Test included 7 standardized timed tasks: 50-foot floor walk, donning and doffing a lab coat, picking up penny from floor, Five-times Sit to Stand test from a 41cm chair without using upper extremities, lifting a 7-pound book, climbing one flight of stairs, standing balance and two untimed tasks: climb up/down 4 flights of stairs and performing a 360 degree turn.32 Each component is scored 0 to 4 with a maximum score of 36. Scores 25 to 31 indicate mild frailty.18 The Four-meter walk test (gait-speed) measures time to walk 4-meters (meter/second).30 The Six Minute Walk test measures distance (meters) walked in 6-minutes.30 The Timed Up and Go (TUG) measures time (s) to rise from a chair, walk 10-meters turn and return seated to the chair.30 The four-meter walk test, 6MW and TUG are well described in the literature and have good to excellent reliability among older adults with arthritis.30,31 The Patient-Reported Outcome Measuremement Information System (PROMIS) Physical Function questionnaire is scored using a t-score metric and is calibrated to have the population mean be a t-score of 50 with the standard deviation set to be 10.33 Scores range from 0-100 and higher t-scores indicate improved physical function.
Health related quality of life (HrQol). Participants completed a battery of patient reported HRQoL outcomes including, PROMIS Global Health Scale v.1.0 (both physical and mental health individual scores), the modified Scoliosis Research Society 30, self-image domain and the Physical Activity Scale for the Elderly.34-36 For all HrQol measures, an increase in score indicates an improvement within the specific domain (see table 2 for score ranges). Pain and self-rated general health outcomes were extracted from single questions within the PROMIS Scale v.1.0 - Global Health.37 The pain measurement within the PROMIS Global Health questionnaire utilizes a visual analogue scale and states ‘In the past 7 days, how would you rate your pain on average’ 0 indicates ‘no pain’ and 10 indicates ‘worst imaginable pain’.
Spinal Strength. Spinal strength was measured using the Biodex 3 (Biodex Medical Systems Inc, Shirley, NY), a computerized dynamometer for spinal flexors and spinal extensors.17 Spinal endurance was measured with the Timed Loaded Standing test, a combined measure of trunk and arm endurance, and is quantified as the time in seconds able to hold a 2-pound dumbbell in each hand with both shoulders flexed to 90 degrees and elbows extended to neutral.38
Spinal Curvature and Cobb angle kyphosis. Clinical measures of thoracic kyphosis and lumbar lordosis were measured in a usual standing posture with the Debruenner Kyphometer (Techmedica Inc., Camarillo, CA).39,40 Cobb angle of kyphosis measurements were made from standing lateral spine radiographs according to standardized protocols by an experienced radiologist.41
Adherence and Safety. Adherence, adverse events and non-reportable events were monitored by the study coordinator, who administered a standardized questionnaire on a weekly basis during the active intervention. Adverse events are defined as any unfavorable medical occurrence and problems that are possibly related to study participation serious or unexpected. Non-reportable events are expected symptoms that may occur during the intervention and described in the study protocol and disclosed in the consent. Examples of non-reportable events in this study are muscle or joint soreness or exacerbation of previous injuries associated with the intervention and resolved within an expected duration of time.42
Data analysis for secondary analysis. Baseline characteristics were compared between the LFG and HFG using t-tests or Wilcoxon nonparametric tests for continuous variables and the χ2 statistic for categorical variables. We calculated mean differences and 95% confidence intervals for change pre/post treatment unadjusted for any covariates for all outcome measures in the LFG and HFG. We compared the pre/post change scores in the LFG and HFG using t-tests. P-values < 0.05 were considered statistically significant. Analyses were conducted using SAS Version 9.4 (SAS Inc, Cary, NC). In this post-hoc secondary analysis, we did not have power to detect significant differences within the groups based upon the small sample size in the subgroups. We determined sample sizes needed for a future study to test the hypothesis that older adults with hyperkyphosis and low physical function will improve physical function on the SPPB after a kyphosis exercise and posture training intervention. Sample size calculations were conducted using PASS 15.0.3 software.