Effects of perioperative analgesic technique on rate of recovery after colon surgery

BACKGROUND

Choice of perioperative analgesia may affect the rate of recovery of gastrointestinal function and thus duration and cost of hospitalization after colonic surgery.

METHODS

Fifty-four patients undergoing partial colectomy surgery were randomized into four groups. All groups received a standardized general anesthetic. Group MB received a preoperative bolus of epidural bupivacaine and morphine followed by an infusion of morphine and bupivacaine. Group M received a preoperative bolus of epidural morphine followed by an infusion of morphine. Group B received a preoperative bolus of bupivacaine followed by an infusion of bupivacaine. Group P received a preoperative bolus of intravenous morphine followed by intravenous patient-controlled morphine postoperatively. All patients participated in a standardized recovery program to minimize the influence of nonanalgesic factors on recovery of gastrointestinal function. All epidural groups were double-blinded. All patients were deemed ready for discharge according to prospectively defined criteria.

RESULTS

Groups B and MB reported superior analgesia with activity (P < 0.01). Group M had a greater incidence of pruritus (P < 0.05). Group B had a greater incidence of orthostatic hypotension (P = 0.04). Groups B and MB recovered gastrointestinal function and fulfilled discharge criteria approximately 1.5 days earlier than groups M and P (P < 0.005).

CONCLUSIONS

Epidural analgesia with bupivacaine and morphine provided the best balance of analgesia and side effects while accelerating postoperative recovery of gastrointestinal function and time to fulfillment of discharge criteria after colon surgery in relatively healthy patients within the context of a multimodal recovery program.

High-trauma fractures and low bone mineral density in older women and men

CONTEXT

It is widely believed that fractures resulting from high trauma are not osteoporotic; however, this assumption has not been studied prospectively.

OBJECTIVE

To examine the association between bone mineral density (BMD) and high-trauma fracture and between high-trauma fracture and subsequent fracture in older women and men.

DESIGN, SETTING, AND PARTICIPANTS

Two prospective US cohort studies in community-dwelling adults 65 years or older from geographically diverse sites. The Study of Osteoporotic Fractures followed up 8022 women for 9.1 years (1988-2006). The Osteoporotic Fractures in Men Study followed up 5995 men for 5.1 years (2000-2007).

MAIN OUTCOME MEASURES

Hip and spine BMD were assessed by dual-energy x-ray absorptiometry. Incident nonspine fractures were confirmed by radiographic report. Fractures were classified, without knowledge of BMD, as high trauma (due to motor vehicle crashes and falls from greater than standing height) or as low trauma (due to falls from standing height and less severe trauma).

RESULTS

Overall, 264 women and 94 men sustained an initial high-trauma fracture and 3211 women and 346 men sustained an initial low-trauma fracture. For women, each 1-SD reduction in total hip BMD was similarly associated with an increased risk of high-trauma fracture (multivariate relative hazard [RH], 1.45; 95% confidence interval [CI], 1.23-1.72) and low-trauma fracture (RH, 1.49; 95% CI, 1.42-1.57). Results were consistent in men (high-trauma fracture RH, 1.54; 95% CI, 1.20-1.96; low-trauma fracture RH, 1.69; 95% CI, 1.49-1.91). Risk of subsequent fracture was 34% (95% CI, 7%-67%) greater among women with an initial high-trauma fracture and 31% (95% CI, 20%-43%) greater among women with an initial low-trauma fracture, compared with women having no high- or low-trauma fracture, respectively. Risk of subsequent fracture was not modeled for men.

CONCLUSIONS

Similar to low-trauma nonspine fractures, high-trauma nonspine fractures are associated with low BMD and increased risk of subsequent fracture in older adults. High-trauma nonspine fractures should be included as outcomes in osteoporosis trials and observational studies.

Skeletal muscle mitochondrial energetics are associated with maximal aerobic capacity and walking speed in older adults

BACKGROUND

Lower ambulatory performance with aging may be related to a reduced oxidative capacity within skeletal muscle. This study examined the associations between skeletal muscle mitochondrial capacity and efficiency with walking performance in a group of older adults.

METHODS

Thirty-seven older adults (mean age 78 years; 21 men and 16 women) completed an aerobic capacity (VO2 peak) test and measurement of preferred walking speed over 400 m. Maximal coupled (State 3; St3) mitochondrial respiration was determined by high-resolution respirometry in saponin-permeabilized myofibers obtained from percutanous biopsies of vastus lateralis (n = 22). Maximal phosphorylation capacity (ATPmax) of vastus lateralis was determined in vivo by (31)P magnetic resonance spectroscopy (n = 30). Quadriceps contractile volume was determined by magnetic resonance imaging. Mitochondrial efficiency (max ATP production/max O2 consumption) was characterized using ATPmax per St3 respiration (ATPmax/St3).

RESULTS

In vitro St3 respiration was significantly correlated with in vivo ATPmax (r (2) = .47, p = .004). Total oxidative capacity of the quadriceps (St3*quadriceps contractile volume) was a determinant of VO2 peak (r (2) = .33, p = .006). ATPmax (r (2) = .158, p = .03) and VO2 peak (r (2) = .475, p < .0001) were correlated with preferred walking speed. Inclusion of both ATPmax/St3 and VO2 peak in a multiple linear regression model improved the prediction of preferred walking speed (r (2) = .647, p < .0001), suggesting that mitochondrial efficiency is an important determinant for preferred walking speed.

CONCLUSIONS

Lower mitochondrial capacity and efficiency were both associated with slower walking speed within a group of older participants with a wide range of function. In addition to aerobic capacity, lower mitochondrial capacity and efficiency likely play roles in slowing gait speed with age.

Excitability changes in human forearm corticospinal projections and spinal reflex pathways during rhythmic voluntary movement of the opposite limb

Rhythmic movements brought about by the contraction of muscles on one side of the body give rise to phase-locked changes in the excitability of the homologous motor pathways of the opposite limb. Such crossed facilitation should favour patterns of bimanual coordination in which homologous muscles are engaged simultaneously, and disrupt those in which the muscles are activated in an alternating fashion. In order to examine these issues, we obtained responses to transcranial magnetic stimulation (TMS), to stimulation of the cervicomedullary junction (cervicomedullary-evoked potentials, CMEPs), to peripheral nerve stimulation (H-reflexes and f-waves), and elicited stretch reflexes in the relaxed right flexor carpi radialis (FCR) muscle during rhythmic (2 Hz) flexion and extension movements of the opposite (left) wrist. The potentials evoked by TMS in right FCR were potentiated during the phases of movement in which the left FCR was most strongly engaged. In contrast, CMEPs were unaffected by the movements of the opposite limb. These results suggest that there was systematic variation of the excitability of the motor cortex ipsilateral to the moving limb. H-reflexes and stretch reflexes recorded in right FCR were modulated in phase with the activation of left FCR. As the f-waves did not vary in corresponding fashion, it appears that the phasic modulation of the H-reflex was mediated by presynaptic inhibition of Ia afferents. The observation that both H-reflexes and f-waves were depressed markedly during movements of the opposite indicates that there may also have been postsynaptic inhibition or disfacilitation of the largest motor units. Our findings indicate that the patterned modulation of excitability in motor pathways that occurs during rhythmic movements of the opposite limb is mediated primarily by interhemispheric interactions between cortical motor areas.

Validation of an armband to measure daily energy expenditure in older adults

BACKGROUND

Objective methods to measure daily energy expenditure in studies of aging are needed. We sought to determine the accuracy of total energy expenditure (TEE) and activity energy expenditure (AEE) estimates from the SenseWear Pro armband (SWA) using software versions 6.1 (SWA 6.1) and 5.1 (SWA 5.1) relative to criterion methods in free-living older adults.

METHODS

Participants (n = 19, mean age 82.0 years) wore a SWA for a mean ± SD 12.5 ± 1.1 days, including while sleeping. During this same period, criterion values for TEE were assessed with doubly labeled water and for resting metabolic rate (RMR) with indirect calorimetry. AEE was calculated as 0.9 TEE - RMR.

RESULTS

For TEE, there was no difference in mean ± SD values from doubly labeled water (2,040 ± 472 kcal/day) versus SWA 6.1 (2,012 ± 497 kcal/day, p = .593) or SWA 5.1 (2,066 ± 474 kcal/day, p = .606); individual values were highly correlated between methods (SWA 6.1 r = .893, p < .001; SWA 5.1 r = .901, p < .001) and demonstrated strong agreement (SWA 6.1 intraclass correlation coefficient = .896; SWA 5.1 intraclass correlation coefficient = .904). For AEE, mean values from SWA 6.1 (427 ± 304 kcal/day) were lower by 26.8% than criterion values (583 ± 242 kcal/day, p = .003), and mean values from SWA 5.1 (475 ± 299 kcal/day) were lower by 18.5% than criterion values (p = .021); however, individual values were highly correlated between methods (SWA 6.1 r = .760, p < .001; SWA 5.1 r = .786, p < .001) and demonstrated moderate agreement (SWA 6.1 intraclass correlation coefficient = .645; SWA 5.1 intraclass correlation coefficient = .720). Bland-Altman plots identified no systematic bias for TEE or AEE.

CONCLUSIONS

Acceptable levels of agreement were observed between SWA and criterion measurements of TEE and AEE in older adults.

Effect of ropivacaine on cutaneous capillary blood flow in pigs

The effect of subcutaneous infiltration of ropivacaine and bupivacaine on local cutaneous blood flow was assessed by the laser Doppler method. One milliliter of each of ten test solutions (ropivacaine 0.25% and 0.75%, bupivacaine 0.25% and 0.75%, and saline, each with and without added epinephrine 5 micrograms/ml) was injected subcutaneously at separate sites on the side of each pig (n = 6). Skin blood flow was measured by laser Doppler at all sites before and 5, 10, 15, and 30 min after injection. Subcutaneous injection of ropivacaine 0.25% or 0.75% decreased cutaneous blood flow by a maximum of 52% +/- 11% and 54% +/- 14% (mean +/- SE), respectively. In contrast, bupivacaine 0.25% or 0.75% increased flow by 90% +/- 32% and 82% +/- 48%, and injection of saline increased blood flow by 32% +/- 17%. Cutaneous blood flow after the injection of ropivacaine was significantly lower than after injection of bupivacaine or saline, and was also lower than at the uninjected control site (P = 0.0009). All of the solutions with epinephrine decreased blood flow to a similar extent (48-73%, P = 0.3). The ability of ropivacaine to produce cutaneous vasoconstriction offers several advantages over the other local anesthetics presently available for infiltration anesthesia.

Skeletal Muscle Mitochondrial Function and Fatigability in Older Adults

BACKGROUND

Fatigability increases while the capacity for mitochondrial energy production tends to decrease significantly with age. Thus, diminished mitochondrial function may contribute to higher levels of fatigability in older adults.

METHODS

The relationship between fatigability and skeletal muscle mitochondrial function was examined in 30 participants aged 78.5 ± 5.0 years (47% female, 93% white), with a body mass index of 25.9 ± 2.7 kg/m(2) and usual gait-speed of 1.2 ± 0.2 m/s. Fatigability was defined using rating of perceived exertion (6-20 point Borg scale) after a 5-minute treadmill walk at 0.72 m/s. Phosphocreatine recovery in the quadriceps was measured using (31)P magnetic resonance spectroscopy and images of the quadriceps were captured to calculate quadriceps volume. ATPmax (mM ATP/s) and oxidative capacity of the quadriceps (ATPmax·Quadriceps volume) were calculated. Peak aerobic capacity (VO2peak) was measured using a modified Balke protocol.

RESULTS

ATPmax·Quadriceps volume was associated with VO2peak and was 162.61mM ATP·mL/s lower (p = .03) in those with high (rating of perceived exertion ≥10) versus low (rating of perceived exertion ≤9) fatigability. Participants with high fatigability required a significantly higher proportion of VO2peak to walk at 0.72 m/s compared with those with low fatigability (58.7 ± 19.4% vs 44.9 ± 13.2%, p < .05). After adjustment for age and sex, higher ATPmax was associated with lower odds of having high fatigability (odds ratio: 0.34, 95% CI: 0.11-1.01, p = .05).

CONCLUSIONS

Lower capacity for oxidative phosphorylation in the quadriceps, perhaps by contributing to lower VO2peak, is associated with higher fatigability in older adults.

Mechanisms underlying age-related differences in ability to recover balance with the ankle strategy

Falls cause substantial death and morbidity in the elderly. An important prerequisite to the development of fall prevention interventions is improved understanding of the biomechanical and neuromuscular variables that govern ability to recover balance. In the present study, we examined the relative importance of strength versus speed of response variables in explaining differences in balance recovery performance with the ankle strategy between young and elderly women. Twenty-five young (19-36 years) and 25 community-dwelling elderly women (66-90 years) participated in balance recovery experiments. Subjects were supported in an inclined standing position by a horizontal tether and instructed to recover an upright vertical standing position by contracting their ankle muscles. The maximum initial lean angle from which they could recover balance without release of the tether (which depends primarily on strength) was 19.6% smaller for elderly than young. The maximum initial lean angle from which they could recover balance after the tether was suddenly released (which depends on both strength and speed of response) was 36.1% smaller for elderly than young. Moreover, between-group differences in performance were related to both strength and speed of response. Peak ankle torque was 7.7% smaller in elderly than young during dynamic recovery trials; reaction time was 27% slower in elderly, due to a lengthened muscle response latency, and rate of ankle torque generation was 15.6% slower in elderly. These results suggest that differences in ability to recover balance between young and elderly women associate with variables related to strength and speed of response, and that exercise-based fall prevention programs should include balance and agility training, in addition to strength training.

Objective measures of activity level and mortality in older men

OBJECTIVES

To examine associations between objective measures of activity level and mortality risk in older men.

DESIGN

Prospective cohort study.

SETTING

Six U.S. sites.

PARTICIPANTS

Men aged 71 and older followed an average of 4.5 years (N = 2,918).

MEASUREMENTS

Time awake spent in sedentary behavior (metabolic equivalent (MET) level ≤1.50), light activity (MET level 1.51-2.99), and at least moderate activity (MET level ≥3.00) measured using an activity monitor worn for 5 days or longer and expressed as quartiles. Deaths were confirmed with death certificates; cause of death was adjudicated by review of certificates and records.

RESULTS

During follow-up, 409 (14%) men died. After multivariable adjustment, comparing Q4 with Q1, more time spent in sedentary behavior (Q4 vs Q1, hazard ratio (HR) = 1.51, 95% confidence interval (CI) = 1.10-2.08), less time spent in light activity (Q1 vs Q4, HR = 1.54, 95% CI = 1.06-2.24), and less time spent in at least moderate activity (Q1 vs Q4, HR = 1.56, 95% CI = 1.09-2.25) were similarly associated with greater mortality risk primarily due to higher risks of cardiovascular and noncardiovascular, noncancer death. The association between time spent in sedentary behavior and mortality varied according to time spent at higher activity level. More time spent in sedentary behavior was associated with greater risk of death in men spending 1.2 (median) h/d or more in at least moderate activity (Q4 vs Q1, HR = 2.09, 95% CI = 1.26-3.49) but not in those spending less time (Q4 vs Q1, HR = 1.02, 95% CI = 0.62-1.66) (P = .005 for interaction).

CONCLUSION

In older men exceeding current guidelines on physical activity, more time spent in sedentary behavior is associated with greater mortality risk.

Life-space mobility and mortality in older men: a prospective cohort study

OBJECTIVES

To evaluate the relationship between life-space (the extent, frequency, and independence of an individual's movement) and mortality in older men.

DESIGN

Prospective cohort study.

SETTING

Six U.S. clinical sites.

PARTICIPANTS

Men aged 71 to 98 followed from 2007 to 2011 (N = 3,892).

MEASUREMENTS

Life-space during the past month was assessed as 0 (daily restriction to one's bedroom) to 120 (daily trips outside one's town without assistance) and categorized into 20-point intervals. The primary outcome was noncancer mortality, and secondary outcomes were all-cause, cardiovascular, cancer, and noncardiovascular noncancer mortality.

RESULTS

Over 2.7 years (2007-2011), 373 (9.6%) men died, 230 from noncancer causes. Unadjusted risk of noncancer mortality was 41.2% in men with the lowest level of life-space (0-20 points, n = 34) and 2.4% in men with the highest level of life-space (101-120 points, n = 868), a 17 times difference. In multivariable-adjusted models, there was a strong linear trend between decreasing life-space and increasing risk of noncancer mortality (P = .005). Risk of noncancer mortality was 3.8 times higher (95% confidence interval (CI)=1.3,11.5) in men with the lowest life-space than in those with the highest life-space. Risk of noncancer mortality was 1.3 times higher (95% CI=1.1-1.5) for each standard-deviation (24 point) decrease in life-space. Risk of noncancer mortality was 1.5 times higher (95% CI=1.0-2.3) in men who did not travel beyond their neighborhood without assistance (n = 471). Results were similar for all-cause mortality and did not change after control for chronic disease burden.

CONCLUSION

Life-space predicted a variety of mortality endpoints in older men; scores of 40 or less were associated with mortality independent of other risk factors.

Objective measures of physical activity, fractures and falls: the osteoporotic fractures in men study

OBJECTIVES

To determine the association between objectively measured physical activity (PA), fractures, and falls.

DESIGN

Longitudinal cohort study.

SETTING

Six U.S. clinical sites.

PARTICIPANTS

Two thousand seven hundred thirty-one men with a mean age of 79.

MEASUREMENTS

Total and active energy expenditure (EE) and minutes per day spent in sedentary and moderate intensity activities were measured for at least 5 days. Energy expended at a metabolic equivalent of greater than three was termed active EE. Incident nonspine fractures and falls were identified every 4 months.

RESULTS

Seven hundred fifty-nine (28.2%) men fell at least once over 12 months of follow-up; 186 (6.8%) experienced one or more fractures over an average follow-up of 3.5 ± 0.9 years. The association between PA and falling varied according to age (P interaction = .02). Men younger than 80 with the lowest active EE had a lower risk of falling than men with the highest active EE (relative risk (RR) = 0.75; P trend = .08), whereas men aged 80 and older with the lowest active EE had a higher risk of falling than men with the highest active EE (RR = 1.43, P trend = .09). In multivariate models including health status, men in the lowest quintile of active EE had a significantly higher risk of fracture (hazard ratio (HR) = 1.82, 95% confidence interval (CI) = 1.10-3.00, P trend = .04) than men in highest quintile. Men with <33 min/d of moderate activity had a 70% greater risk of fracture (HR = 1.70, 95% CI = 1.03-2.80).

CONCLUSION

Age modifies the association between PA and falling. Interventions aimed at obtaining more than 30 minutes of moderate PA per day may reduce fractures, extending PA guidelines to the oldest old, the fastest-growing proportion of those aged 65 and older.

Change in hip bone mineral density and risk of subsequent fractures in older men

Low bone mineral density (BMD) increases fracture risk; how changes in BMD influence fracture risk in older men is uncertain. BMD was assessed at two to three time points over 4.6 years using dual-energy X-ray absorptiometry (DXA) for 4470 men aged ≥65 years in the Osteoporotic Fractures in Men (MrOS) Study. Change in femoral neck BMD was estimated using mixed effects linear regression models. BMD change was categorized as "accelerated" (≤-0.034 g/cm(2) ), "expected" (between 0 and -0.034 g/cm(2) ), or "maintained" (≥0 g/cm(2) ). Fractures were adjudicated by central medical record review. Multivariate proportional hazards models estimated the risk of hip, nonspine/nonhip, and nonspine fracture over 4.5 years after the final BMD measure, during which time 371 (8.3%) men experienced at least one nonspine fracture, including 78 (1.7%) hip fractures. Men with accelerated femoral neck BMD loss had an increased risk of nonspine (hazard ratio [HR] = 2.0; 95% confidence interval [CI] 1.4-2.8); nonspine/nonhip (HR = 1.6; 95% CI 1.1-2.3); and hip fracture (HR = 6.3; 95% CI 2.7-14.8) compared with men who maintained BMD over time. No difference in risk was seen for men with expected loss. Adjustment for the initial BMD measure did not alter the results. Adjustment for the final BMD measure attenuated the change in BMD-nonspine fracture and the change in BMD-nonspine/nonhip relationships such that they were no longer significant, whereas the change in the BMD-hip fracture relationship was attenuated (HR = 2.6; 95% CI 1.1-6.4). Total hip BMD change produced similar results. Accelerated decrease in BMD is a strong, independent risk factor for hip and other nonspine fractures in men.

Walking energetics, fatigability, and fatigue in older adults: the study of energy and aging pilot

BACKGROUND

Slow gait speed increases morbidity and mortality in older adults. We examined how preferred gait speed is associated with energetic requirements of walking, fatigability, and fatigue.

METHODS

Older adults (n = 36, 70-89 years) were categorized as slow or fast walkers based on median 400-m gait speed. We measured VO2peak by graded treadmill exercise test and VO2 during 5-minute treadmill walking tests at standard (0.72 m/s) and preferred gait speeds. Fatigability was assessed with the Situational Fatigue Scale and the Borg rating of perceived exertion at the end of walking tests. Fatigue was assessed by questionnaire.

RESULTS

Preferred gait speed over 400 m (range: 0.75-1.58 m/s) averaged 1.34 m/s for fast walkers versus 1.05 m/s for slow walkers (p < .001). VO2peak was 26% lower (18.5 vs 25.1ml/kg/min, p = .001) in slow walkers than fast walkers. To walk at 0.72 m/s, slow walkers used a larger percentage of VO2peak (59% vs 42%, p < .001). To walk at preferred gait speed, slow walkers used more energy per unit distance (0.211 vs 0.186ml/kg/m, p = .047). Slow walkers reported higher rating of perceived exertion during walking and greater overall fatigability on the Situational Fatigue Scale, but no differences in fatigue.

CONCLUSIONS

Slow walking was associated with reduced aerobic capacity, greater energetic cost of walking, and greater fatigability. Interventions to improve aerobic capacity or decrease energetic cost of walking may prevent slowing of gait speed and promote mobility in older adults.

Prediction of clinical non-spine fractures in older black and white men and women with volumetric BMD of the spine and areal BMD of the hip: the Health, Aging, and Body Composition Study*

In a prospective study of 1446 black and white adults 70-79 yr of age (average follow-up, 6.4 yr), vertebral TrvBMD from QCT predicted non-spine fracture in black and white women and black men, but it was not a stronger predictor than total hip aBMD from DXA. Hip aBMD predicted non-spine fracture in black men.

INTRODUCTION

Areal BMD (aBMD) at multiple skeletal sites predicts clinical non-spine fractures in white and black women and white men. The predictive ability of vertebral trabecular volumetric BMD (TrvBMD) for all types of clinical non-spine fractures has never been tested or compared with hip aBMD. Also, the predictive accuracy of hip aBMD has never been tested prospectively for black men.

MATERIALS AND METHODS

We measured vertebral TrvBMD with QCT and hip aBMD with DXA in 1446 elderly black and white adults (70-79 yr) in the Health, Aging, and Body Composition Study. One hundred fifty-two clinical non-spine fractures were confirmed during an average of 6.4 yr of >95% complete follow-up. We used Cox proportional hazards regression to determine the hazard ratio (HR) and 95% CIs of non-spine fracture per SD reduction in hip aBMD and vertebral TrvBMD.

RESULTS

Vertebral TrvBMD and hip aBMD were both associated with risk of non-spine fracture in black and white women and black men. The age-adjusted HR of fracture per SD decrease in BMD was highest in black men (hip aBMD: HR = 2.04, 95% CI = 1.03, 4.04; vertebral TrvBMD: HR = 3.00, 95% CI = 1.29, 7.00) and lowest in white men (hip aBMD: HR = 1.23, 95% CI = 0.85, 1.78; vertebral TrvBMD: HR = 1.06, 95% CI = 0.73, 1.54). Adjusted for age, sex, and race, each SD decrease in hip aBMD was associated with a 1.67-fold (95% CI = 1.36, 2.07) greater risk of fracture, and each SD decrease in vertebral TrvBMD was associated with a 1.47-fold (95% CI = 1.18, 1.82) greater risk. Combining measurements of hip aBMD and vertebral TrvBMD did not improve fracture prediction.

CONCLUSIONS

Low BMD measured by either spine QCT or hip DXA predicts non-spine fracture in older black and white women and black men. Vertebral TrvBMD is not a stronger predictor than hip aBMD of non-spine fracture.

Postural steadiness during quiet stance does not associate with ability to recover balance in older women

BACKGROUND

Fall risk depends on ability to maintain balance during daily activities, and on ability to recover balance following a perturbation such as a slip or trip. We examined whether similar neuromuscular variables govern these two domains of postural stability.

METHODS

We conducted experiments with 25 older women (mean age=78 yrs, SD=7 yrs). We acquired measures of postural steadiness during quiet stance (mean amplitude, velocity, and frequency of centre-of-pressure movement when standing with eyes open or closed, on a rigid or compliant surface). We also measured ability to recover balance using the ankle strategy after release from a forward leaning position (based on the maximum release angle where recovery was possible, and corresponding values of reaction time, rate of ankle torque generation, and peak ankle torque).

FINDINGS

We found that balance recovery variables were not strongly or consistently correlated with postural steadiness variables. The maximum release angle associated with only three of the sixteen postural steadiness variables (mean frequency in rigid, eyes open condition (r=0.36, P=.041), and mean amplitude (r=0.41, P=.038) and velocity (r=0.49, P=.015) in compliant, eyes closed condition). Reaction time and peak torque did not correlate with any steadiness variables, and rate of torque generation correlated moderately with the mean amplitude and velocity of the centre-of-pressure in the compliant, eyes closed condition (r=0.48-0.60).

INTERPRETATION

Our results indicate that postural steadiness during quiet stance is not predictive of ability to recover balance with the ankle strategy. Accordingly, balance assessment and fall prevention programs should individually target these two components of postural stability.

Effects of antiresorptive treatment on nonvertebral fracture outcomes

Various definitions of nonvertebral fracture have been used in osteoporosis trials, precluding comparisons of efficacy. Using only subgroups of nonvertebral fractures for trial outcomes may underestimate the benefits and cost-effectiveness of treatments. The objectives of this study were to determine (1) the effect of antiresorptive treatment on various nonvertebral fracture outcomes, (2) whether risk reduction from antiresorptive treatment is greater for nonvertebral fractures that have stronger associations with low BMD, and (3) sample size estimates for clinical trials of osteoporosis treatments. Study-level data were combined from five randomized fracture-prevention trials of antiresorptive agents that reduce the risk of nonvertebral fracture in postmenopausal women: alendronate, clodronate, denosumab, lasofoxifene, and zoledronic acid. Pooled effect estimates were calculated with random-effects models. The five trials included 30,118 women; 2997 women had at least one nonvertebral fracture. There was no significant heterogeneity between treatments for any outcome (all p > 0.10). Antiresorptive treatment had similar effects on all fractures (summary hazard ratio [HR] = 0.76, 95% CI 0.70-0.81), high-trauma fractures (HR = 0.74, 95% CI 0.57-0.96), low-trauma fractures (HR = 0.77, (95% CI 0.71-0.83), nonvertebral six (ie, hip, pelvis, leg, wrist, humerus, and clavicle) fractures (HR = 0.73, 95% CI 0.66-0.80), other than nonvertebral six fractures (HR = 0.78, 95% CI 0.70-0.87), and all fractures other than finger, face, and toe (HR = 0.75, 95% CI 0.70-0.81). Risk reduction was not greater for fractures with stronger associations with low BMD (p = 0.77). A trial of all nonvertebral fractures would require fewer participants (n = 2641 per arm) than one of a subgroup of six fractures (n = 3289), for example. In summary, antiresorptive treatments reduced all nonvertebral fractures regardless of degree of trauma or special groupings, supporting the use of all nonvertebral fractures as a standard endpoint of osteoporosis trials and the basis for estimating the benefits and cost-effectiveness of treatments.

Life-Space Mobility and Mortality in Older Women: Prospective Results from the Study of Osteoporotic Fractures

OBJECTIVES

To evaluate the relationship between life-space mobility (extent, frequency, independence of movement) and mortality in older women.

DESIGN

Prospective cohort study.

SETTING

Four U.S. clinical sites.

PARTICIPANTS

Women (N = 1,498) aged 75 to 102 (mean 87.6) followed from 2006 to 2015.

MEASUREMENTS

Life-space during the past 4 weeks was assessed in an interview, scored from 0 (daily restriction to bedroom) to 120 (daily trips outside town without assistance), and categorized (0-20, 21-40, 41-60, 61-80, 81-120). All-cause mortality was the primary outcome; noncancer, cardiovascular, cancer, and noncardiovascular noncancer mortality were secondary outcomes.

RESULTS

Over a mean 5.2 years, 842 (56.2%) women died. Unadjusted risk of all-cause mortality was 82.6% in women with the lowest level of life-space (0-20 points) and 36.2% in those with the highest level (81-120 points). In multivariable proportional hazards models, there was a strong relationship between less life-space and greater risk of all-cause mortality (P_trend < .001). Women with the lowest level of life-space (0-20 points) had a risk of all-cause mortality that was 2.4 times as high (95% confidence interval (CI) = 1.5-4.0) as that of women with the highest level (81-120 points); women with life-space scores between 21 and 60 had a risk of all-cause mortality that was 1.5 times as high as that of women with the highest level. Each standard deviation decrease in life-space was associated with a 1.2 times greater (95% CI = 1.1-1.4) risk of all-cause mortality. Women unable to travel beyond their neighborhood without assistance had a risk of all-cause mortality that was 1.4 times (95% CI = 1.1-1.7) as high as that of women who could travel beyond their neighborhood without assistance. Results were similar for noncancer, cardiovascular, and other mortality and did not change after controlling for underlying disease or living arrangement.

CONCLUSION

Life-space scores of 60 or less were associated with mortality in older women independent of other strong risk factors.

Changes in proximal femoral mineral geometry precede the onset of radiographic hip osteoarthritis: The study of osteoporotic fractures

OBJECTIVE

Radiographic hip osteoarthritis (RHOA) is associated with increased hip areal bone mineral density (aBMD). This study was undertaken to examine whether femoral geometry is associated with RHOA independent of aBMD.

METHODS

Participants in the Study of Osteoporotic Fractures in whom pelvic radiographs had been obtained at visits 1 and 5 (mean 8.3 years apart) and hip dual x-ray absorptiometry (DXA) had been performed (2 years after baseline) were included. Prevalent and incident RHOA phenotypes were defined as composite (osteophytes and joint space narrowing [JSN]), atrophic (JSN without osteophytes), or osteophytic (femoral osteophytes without JSN). Analogous definitions of progression were based on minimum joint space and total osteophyte score. Hip DXA scans were assessed using the Hip Structural Analysis program to derive geometric measures, including femoral neck length, width, and centroid position. Relative risks and 95% confidence intervals for prevalent, incident, and progressive RHOA per SD increase in geometric measure were estimated in a hip-based analysis using multinomial logistic regression with adjustment for age, body mass index, knee height, and total hip aBMD.

RESULTS

In 5,245 women (mean age 72.6 years), a wider femoral neck with a more medial centroid position was associated with prevalent and incident osteophytic and composite RHOA phenotypes (P < 0.05). Increased neck width and centroid position were associated with osteophyte progression (both P < 0.05). No significant geometric associations with atrophic RHOA were found.

CONCLUSION

Differences in proximal femoral bone geometry and spatial distribution of bone mass occur early in hip OA and predict prevalent, incident, and progressive osteophytic and composite phenotypes, but not the atrophic phenotype. These bone differences may reflect responses to loading occurring early in the natural history of RHOA.

Longitudinal change in energy expenditure and effects on energy requirements of the elderly

Background

Very little is known about the longitudinal changes in energy requirements in late life. The purposes of this study were to: (1) determine the energy requirements in late life and how they changed during a 7 year time-span, (2) determine whether changes in fat free mass (FFM) were related to changes in resting metabolic rate (RMR), and (3) determine the accuracy of predicted total energy expenditure (TEE) to measured TEE.

Methods

TEE was assessed via doubly labeled water (DLW) technique in older adults in both 1999 (n = 302; age: 74 ± 2.9 yrs) and again in 2006 (n = 87 age: 82 ± 3.1 yrs). RMR was measured with indirect calorimetry, and body composition was assessed with dual-energy x-ray absorptiometry.

Results

The energy requirements in the 9th decade of life were 2208 ± 376 kcal/d for men and 1814 ± 337 kcal/d for women. This was a significant decrease from the energy requirements in the 8th decade of life in men (2482 ± 476 kcal/d vs. 2208 ± 376 kcal/d) but not in women (1892 ± 271 kcal/d vs. 1814 ± 337 kcal/d). In addition to TEE, RMR, and activity EE (AEE) also decreased in men, but not women, while FFM decreased in both men and women. The changes in FFM were correlated with changes in RMR for men (r = 0.49, p < 0.05) but not for women (r = −0.08, ns). Measured TEE was similar to Dietary Reference Intake (DRI) predicted TEE for men (2208 ± 56 vs. 2305 ± 35 kcal/d) and women (1814 ± 42 vs. 1781 ± 20 kcal/d). However, measured TEE was different than the World Health Organization (WHO) predicted TEE in men (2208 ± 56 vs. 2915 ± 31 kcal/d (p < 0.05)) and women (1814 ± 42 vs. 2315 ± 21 kcal/d (p < 0.05)).

Conclusions

TEE, RMR and AEE decreased in men, but not women, from the 8th to 9th decade of life. The DRI equation to predict TEE was comparable to measured TEE, while the WHO equation over-predicted TEE in our elderly population.

Activity energy expenditure and change in body composition in late life

BACKGROUND

Change in body composition, specifically loss of fat-free mass and gain in fat mass, in older adults is a major pathway leading to the onset of functional decline and physical disability.

OBJECTIVE

The objective was to determine the association of activity-related energy expenditure with change in body mass and composition among older men and women.

DESIGN

Total energy expenditure (TEE) was assessed over 2 wk by using the doubly labeled water method in 302 community-dwelling older adults aged 70-82 y. Resting metabolic rate (RMR) was measured by using indirect calorimetry, and the thermic effect of meals was estimated at 10% of TEE. Activity energy expenditure (AEE) was calculated as [TEE(0.9) - RMR]. Total body mass, fat-free mass (FFM), and fat mass (FM) were assessed by dual-energy X-ray absorptiometry annually over a mean (+/-SD) of 4.9 +/- 1.3 y.

RESULTS

In multivariate models adjusted for baseline age, smoking status, and race, men and women had a decline (in kg/y) in body mass (men: -0.34, 95% CI: -0.71, 0.02; women: -0.45, 95% CI: -0.71, -0.19) and FFM (men: -0.48, 95% CI: -0.67, -0.29; women: -0.14, 95% CI: -0.026, -0.03). No changes (in kg/y) were observed in FM (men: 0.14, 95% CI: -0.10, 0.38; women: -0.28, 95% CI: -0.49, -0.07). In men and women, higher AEE at baseline was associated with greater FFM. The average change in these outcomes (ie, slope), however, was similar across tertiles of AEE.

CONCLUSIONS

These data suggest that accumulated energy expenditure from all physical activities is associated with greater FFM, but the effect does not alter the trajectory of FFM change in late life.

Compliant flooring to prevent fall-related injuries in older adults: A scoping review of biomechanical efficacy, clinical effectiveness, cost-effectiveness, and workplace safety

BACKGROUND

Compliant flooring, broadly defined as flooring systems or floor coverings with some level of shock absorbency, may reduce the incidence and severity of fall-related injuries in older adults; however, a lack of synthesized evidence may be limiting widespread uptake.

METHODS

Informed by the Arksey and O'Malley framework and guided by a Research Advisory Panel of knowledge users, we conducted a scoping review to answer: what is presented about the biomechanical efficacy, clinical effectiveness, cost-effectiveness, and workplace safety associated with compliant flooring systems that aim to prevent fall-related injuries in healthcare settings? We searched academic and grey literature databases. Any record that discussed a compliant flooring system and at least one of biomechanical efficacy, clinical effectiveness, cost-effectiveness, or workplace safety was eligible for inclusion. Two independent reviewers screened and abstracted records, charted data, and summarized results.

RESULTS

After screening 3611 titles and abstracts and 166 full-text articles, we included 84 records plus 56 companion (supplementary) reports. Biomechanical efficacy records (n = 50) demonstrate compliant flooring can reduce fall-related impact forces with minimal effects on standing and walking balance. Clinical effectiveness records (n = 20) suggest that compliant flooring may reduce injuries, but may increase risk for falls. Preliminary evidence suggests that compliant flooring may be a cost-effective strategy (n = 12), but may also result in increased physical demands for healthcare workers (n = 17).

CONCLUSIONS

In summary, compliant flooring is a promising strategy for preventing fall-related injuries from a biomechanical perspective. Additional research is warranted to confirm whether compliant flooring (i) prevents fall-related injuries in real-world settings, (ii) is a cost-effective intervention strategy, and (iii) can be installed without negatively impacting workplace safety. Avenues for future research are provided, which will help to determine whether compliant flooring is recommended in healthcare environments.

Population attributable fraction of type 2 diabetes due to physical inactivity in adults: a systematic review

Background

Physical inactivity is a global pandemic. The population attributable fraction (PAF) of type 2 diabetes mellitus (T2DM) associated with physical inactivity ranges from 3% to 40%. The purpose of this systematic review was to determine the best estimate of PAF for T2DM attributable to physical inactivity and absence of sport participation or exercise for men and women.

Methods

We conducted a systematic review that included a comprehensive search of MEDLINE, EMBASE, SportDiscus, and CINAHL (1946 to April 30 2013) limited by the terms adults and English. Two reviewers screened studies, extracted PAF related data and assessed the quality of the selected studies. We reconstructed 95% CIs for studies missing these data using a substitution method.

Results

Of the eight studies reporting PAF in T2DM, two studies included prospective cohort studies (3 total) and six were reviews. There were distinct variations in quality of defining and measuring physical inactivity, T2DM and adjusting for confounders. In the US, PAFs for absence of playing sport ranged from 13% (95% CI: 3, 22) in men and 29% (95% CI: 17, 41) in women. In Finland, PAFs for absence of exercise ranged from 3% (95% CI: -11, 16) in men to 7% (95% CI: -9, 20) in women.

Conclusions

The PAF of physical inactivity due to T2DM is substantial. Physical inactivity is a modifiable risk factor for T2DM. The contribution of physical inactivity to T2DM differs by sex; PAF also differs if physical inactivity is defined as the absence of ‘sport’ or absence of ‘exercise’.

Objective assessment of activity, energy expenditure, and functional limitations in older men: the Osteoporotic Fractures in Men study

BACKGROUND

The relationship between objectively assessed activity, energy expenditure, and the development of functional limitations is unknown.

METHODS

Energy expenditure and activity levels were measured objectively using the multisensor SenseWear Pro Armband worn for greater than or equal to 5 days in 1,983 MrOS men (aged ≥ 78.3 years) free of functional limitations. Validated algorithms calculated energy expenditure; standard cut points defined moderate or greater activity (≥ 3.0 METS); and sedentary behavior (time awake ≤ 1.5 METS). Self-reported functional limitation was determined at the activity assessment and 2.0 years later as inability to perform instrumental activities of daily living (managing money, managing medications, shopping, housework, and meal preparation) and activities of daily living (climb stairs, walk two to three blocks, transfer, or bathe).

RESULTS

Each standard deviation decrease in total energy expenditure (420.6 kcal/day) increased the likelihood of inability to perform an instrumental activity of daily living (multivariate odds ratio [mOR]: 1.61, 95% CI: 1.30-2.00) or activity of daily living (mOR: 1.35, 95% CI: 1.12-1.63). Each standard deviation decrease in moderate or greater activity (61.1 minutes/day) increased the likelihood of inability to perform an instrumental activity of daily living (mOR: 1.47, 95% CI: 1.22-1.78) or activity of daily living (mOR: 1.36, 95% CI: 1.14-1.61). Each standard deviation increase in minutes of sedentary behavior (105.2 minutes/day) increased the likelihood of inability to perform an instrumental activity of daily living (mOR: 1.20, 95% CI: 1.03-1.40) or activity of daily living (mOR: 1.17, 95% CI: 1.01-1.35).

CONCLUSION

Older men with lower total energy expenditure, lower moderate activity, or greater sedentary time were more likely to develop a functional limitation.

Risk factors for hip impact during real-life falls captured on video in long-term care

Hip fracture risk is increased by landing on the hip. We examined factors that contribute to hip impact during real-life falls in long-term care facilities. Our results indicate that hip impact is equally likely in falls initially directed forward as sideways and more common among individuals with dependent Activities of Daily Living (ADL) performance.

INTRODUCTION

The risk for hip fracture in older adults increases 30-fold by impacting the hip during a fall. This study examined biomechanical and health status factors that contribute to hip impact through the analysis of real-life falls captured on video in long-term care (LTC) facilities.

METHODS

Over a 7-year period, we captured 520 falls experienced by 160 residents who provided consent for releasing their health records. Each video was analyzed by a three-member team using a validated questionnaire to determine whether impact occurred to the hip or hand, the initial fall direction and landing configuration, attempts of stepping responses, and use of mobility aids. We also collected information related to resident physical and cognitive function, disease diagnoses, and use of medications from the Minimum Data Set.

RESULTS

Hip impact occurred in 40 % of falls. Falling forward or sideways was significantly associated with higher odds of hip impact, compared to falling backward (OR 4.2, 95 % CI 2.4-7.1) and straight down (7.9, 4.1-15.6). In 32 % of sideways falls, individuals rotated to land backward. This substantially reduced the odds for hip impact (0.1, 0.03-0.4). Tendency for body rotation was decreased for individuals with dependent ADL performance (0.43, 0.2-1.0).

CONCLUSIONS

Hip impact was equally likely in falls initially directed forward as sideways, due to the tendency for axial body rotation during descent. A rotation from sideways to backward decreased the odds of hip impact 10-fold. Our results may contribute to improvements in risk assessment and strategies to reduce risk for hip fracture in older adults.