Impairments of muscles and nerves associated with peripheral arterial disease and their relationship with lower extremity functioning: the InCHIANTI Study

To what extent can multimorbidity be viewed as a determinant of postural control in stroke patients?

OBJECTIVE

To investigate the determinants of postural imbalance after stroke in geriatric patients admitted for low-intensity rehabilitation in skilled nursing facilities (SNFs), particularly the role of multimorbidity.

DESIGN

Cross-sectional study design.

SETTING

Fifteen SNFs.

PARTICIPANTS

All patients who were admitted for rehabilitation after stroke in one of the participating SNFs (N=378) were eligible.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The Berg Balance Scale (BBS) was selected as a measure of standing balance and the Functional Ambulation Categories (FAC) as a measure of walking balance.

RESULTS

Multimorbidity was present in 34% of the patients. The patients with multimorbidity differed from the patients without multimorbidity with respect to age, proprioception, and vibration sense, but not for any of the cognitive tests, muscle strength, or sitting balance. Patients with multimorbidity had, on average, lower scores on both outcome measures. In linear regression analyses, both the BBS and FAC were best explained by multimorbidity, muscle strength, and the interaction between muscle strength and static sitting balance (overall explained variance 66% and 67%, respectively), while proprioception added only to the variance of the FAC.

CONCLUSIONS

Multimorbidity was independently related to postural imbalance after stroke in patients admitted for rehabilitation in SNFs. Muscle strength and the interaction of muscle strength with static sitting balance were important determinants of both standing and walking balance, indicating these factors as essential targets for rehabilitation.

Associations of calf skeletal muscle characteristics and peripheral nerve function with self-perceived physical functioning and walking ability in persons with peripheral artery disease

We determined whether more adverse calf muscle characteristics and poorer peripheral nerve function were associated with impairments in self-perceived physical functioning and walking ability in persons with lower extremity peripheral artery disease (PAD). Participants included 462 persons with PAD; measures included the ankle-brachial index (ABI), medical history, electrophysiologic characteristics of nerves, and computed tomography of calf muscle. Self-perceived physical functioning and walking ability were assessed using the 36-Item Short Form Health Survey (SF-36) and the Walking Impairment Questionnaire (WIQ). Results were adjusted for age, sex, race, ABI, body mass index, comorbidities, and other confounders. Lower calf muscle area was associated with a poorer SF-36 physical function (PF) score (overall p-trend < 0.001, 33.76 PF score for the lowest quartile versus 59.74 for the highest, pairwise p < 0.001) and a poorer WIQ walking distance score (p-trend = 0.001, 29.71 WIQ score for the lowest quartile versus 48.43 for the highest, pairwise p < 0.001). Higher calf muscle percent fat was associated with a poorer SF-36 PF score (p-trend < 0.001, 53.76 PF score for the lowest quartile versus 40.28 for the highest, pairwise p = 0.009). Slower peroneal nerve conduction velocity was associated with a poorer WIQ speed score ( p-trend = 0.023, 30.49 WIQ score for the lowest quartile versus 40.48 for the highest, pairwise p = 0.031). In summary, adverse calf muscle characteristics and poorer peripheral nerve function are associated significantly and independently with impairments in self-perceived physical functioning and walking ability in PAD persons.

Greater sedentary hours and slower walking speed outside the home predict faster declines in functioning and adverse calf muscle changes in peripheral arterial disease

OBJECTIVES

In participants with peripheral arterial disease (PAD), we determined whether more sedentary behavior and slower outdoor walking speed were associated with faster functional decline and more adverse changes in calf muscle characteristics over time.

BACKGROUND

Modifiable behaviors associated with faster functional decline in lower-extremity PAD are understudied.

METHODS

Participants were 384 men and women with an ankle brachial index <0.90 followed for a median of 47 months. At baseline, participants reported the number of hours they spent sitting per day and their walking speeds outside their homes. Participants underwent baseline and annual measures of objective functional performance. Calf muscle characteristics were measured with computed tomography at baseline and every 2 years subsequently. Analyses were adjusted for age, sex, race, comorbidities, ankle brachial index, and other confounders.

RESULTS

Slower walking speed outside the home was associated with faster annual decline in calf muscle density (brisk/striding pace -0.32 g/cm(3), average pace -0.46 g/cm(3), casual strolling -1.03 g/cm(3), no walking at all -1.43 g/cm(3), p trend <0.001). Greater hours sitting per day were associated with faster decline in 6-min walk (<4 h: -35.8 feet/year; 4 to <7 h: -41.1 feet/year; 8 to <11 h: -68.7 feet; ≥12 h: -78.0 feet; p trend = 0.008). Similar associations were observed for greater hours sitting per day and faster declines in fast-paced (p trend = 0.018) and usual-paced (p trend < 0.001) 4-m walking velocity.

CONCLUSIONS

Greater sedentary hours per day and slower outdoor walking speed are modifiable behaviors that are associated with faster functional decline and greater decline in calf muscle density, respectively, in patients with PAD.

Sarcopenia: designing phase IIB trials

Sarcopenia is the age-related involuntary loss of skeletal muscle mass and functionality that can lead to the development of disability, frailty and increased health care costs. The development of interventions aimed at preventing and/or treating sarcopenia is complex, requiring the adoption of assumptions and standards that are not well established scientifically or clinically. A number of investigators and clinicians (both from academia and industry) met in Rome (Italy) in 2009 to develop a consensus definition of sarcopenia. Subsequently, in Albuquerque (New Mexico, USA) in 2010, the same group met again to consider the complex issues necessary for designing Phase II clinical trials for sarcopenia. Current clinical trial data indicate that fat-free mass (FFM) parameters are responsive to physical activity/nutritional treatment modalities over short time periods, but pharmacological trials of sarcopenia have yet to show significant efficacy. In order to conduct a clinical trial within a reasonable time frame, groups that model or display accelerated aging and loss of FFM are necessary. Few studies have used acceptable designs for testing treatment effects, sample sizes or primary outcomes that could provide interpretable findings or effects across studies. Dual energy x-ray absorptiometry (DXA) is the measure of choice for assessing FFM, but sufficient time is needed for changes to be detected accurately and reliably. A tool set that would allow clinical, basic and epidemiological research on sarcopenia to advance rapidly toward diagnosis and treatment phases should be those reflecting function and strength.

Sarcopenia: an undiagnosed condition in older adults. Current consensus definition: prevalence, etiology, and consequences. International working group on sarcopenia

Sarcopenia, the age-associated loss of skeletal muscle mass and function, has considerable societal consequences for the development of frailty, disability, and health care planning. A group of geriatricians and scientists from academia and industry met in Rome, Italy, on November 18, 2009, to arrive at a consensus definition of sarcopenia. The current consensus definition was approved unanimously by the meeting participants and is as follows: Sarcopenia is defined as the age-associated loss of skeletal muscle mass and function. The causes of sarcopenia are multifactorial and can include disuse, altered endocrine function, chronic diseases, inflammation, insulin resistance, and nutritional deficiencies. Although cachexia may be a component of sarcopenia, the 2 conditions are not the same. The diagnosis of sarcopenia should be considered in all older patients who present with observed declines in physical function, strength, or overall health. Sarcopenia should specifically be considered in patients who are bedridden, cannot independently rise from a chair, or who have a measured gait speed less that 1 m/s(-1). Patients who meet these criteria should further undergo body composition assessment using dual energy x-ray absorptiometry with sarcopenia being defined using currently validated definitions. A diagnosis of sarcopenia is consistent with a gait speed of less than 1 m·s(-1) and an objectively measured low muscle mass (eg, appendicular mass relative to ht(2) that is ≤ 7.23 kg/m(2) in men and ≤ 5.67 kg/m(2) in women). Sarcopenia is a highly prevalent condition in older persons that leads to disability, hospitalization, and death.

Relação entre força muscular e capacidade funcional em pacientes com doença arterial obstrutiva periférica: um estudo piloto

CONTEXTO: As informações sobre o grau de correlação entre força muscular e capacidade funcional em pacientes com doença arterial obstrutiva periférica (DAOP) são inconsistentes, além de nem sempre apresentarem protocolos que relacionem apropriadamente medidas de força muscular com desempenho. OBJETIVO: Estabelecer o nível de correlação entre força muscular e capacidade funcional em pacientes fisicamente ativos com DAOP. MÉTODOS: Doze pacientes com diagnóstico da doença e presença de claudicação intermitente participaram do estudo. Todos realizaram testes de força muscular e de caminhada. Grau de correlação entre força muscular e capacidade funcional foi avaliado pela correlação de Pearson. RESULTADOS: Dos 12 voluntários incluídos, 10 eram do sexo masculino e 2 do sexo feminino. Os participantes tinham média de idade de 63 ± 11 anos. Houve alta correlação (r = 0,872; p = 0,0001) entre distância percorrida no teste de deslocamento bidirecional progressivo (TDBP) e carga alcançada no teste de resistência máxima. Não se observou correlação entre distância percorrida no TDBP e tempo gasto para realização das cinco flexões plantares no teste de ponta de pé. CONCLUSÃO: O desempenho funcional em um grupo de pacientes com DAOP, em sua maioria fisicamente ativos, foi fortemente correlacionado com força muscular de extensores de joelho, mas não com desempenho observado funcionalmente pelo teste de ponta de pé. Futuros estudos são necessários para avaliar se força muscular de flexores plantares, mensurada de forma específica e isolada, correlaciona-se com função em pacientes com a doença.

Women with peripheral arterial disease experience faster functional decline than men with peripheral arterial disease

OBJECTIVES

We hypothesized that women with lower extremity peripheral arterial disease (PAD) would have greater mobility loss and faster functional decline than men with PAD.

BACKGROUND

Whether rates of mobility loss or functional decline differ between men and women with PAD is currently unknown.

METHODS

Three hundred eighty men and women with PAD completed the 6-min walk, were assessed for mobility disability, and underwent measures of 4-m walking velocity at baseline and annually for up to 4 years. Computed tomography-assessed calf muscle characteristics were measured biannually. Outcomes included becoming unable to walk for 6 min continuously among participants who walked continuously for 6 min at baseline. Mobility loss was defined as becoming unable to walk for a quarter mile or to walk up and down 1 flight of stairs without assistance among those without baseline mobility disability. Results were adjusted for age, race, body mass index, physical activity, the ankle brachial index, comorbidities, and other confounders.

RESULTS

At 4 years of follow-up, women were more likely to become unable to walk for 6 min continuously (hazard ratio: 2.30, 95% confidence interval: 1.30 to 4.06, p = 0.004), more likely to develop mobility disability (hazard ratio: 1.79, 95% confidence interval: 1.30 to 3.03, p = 0.030), and had faster declines in walking velocity (p = 0.022) and the distance achieved in the 6-min walk (p = 0.041) compared with men. Sex differences in functional decline were attenuated after additional adjustment for baseline sex differences in calf muscle area.

CONCLUSIONS

Women with PAD have faster functional decline and greater mobility loss than men with PAD. These sex differences may be attributable to smaller baseline calf muscle area among women with PAD.

Better glycemic control is associated with maintenance of lower-extremity function over time in Mexican American and European American older adults with diabetes

OBJECTIVE

Diabetes is a major cause of functional decline among older adults, but the role of glycemic control remains unclear. This article assesses whether better glycemic control is associated with better maintenance of lower-extremity function over time in older adults with diabetes.

RESEARCH DESIGN AND METHODS

Participants (n = 119) in the San Antonio Longitudinal Study of Aging, ages 71-85, who met American Diabetes Association diabetes criteria were followed over a 36-month period. Seven measures of A1C (HbA(1c)) were obtained at 6-month intervals; three measures of lower-extremity function were obtained at 18-month intervals using the Short Physical Performance Battery (SPPB). A two-step analytic approach was used, first, to identify distinct glycemic control classes using latent growth mixture modeling and, second, to examine trajectories of lower-extremity function based on these classes using path analysis.

RESULTS

Two glycemic control classes were identified: a poorer control class with higher means (all >7%) and higher within-subject variability in HbA(1c) and a better control class with lower means (all <7%) and lower within-subject variability. The short-term and long-term maintenance of lower-extremity function, assessed by the association between the first and second SPPB measures and the first and third SPPB measures, were both greater in the better control class than in the poorer control class.

CONCLUSIONS

Among older adults with diabetes, better glycemic control may improve both short-term and long-term maintenance of lower-extremity function.

Care of elderly patients with diabetes mellitus: a focus on frailty

The prevalence and incidence of type 2 diabetes mellitus (DM) increase with age, and its diagnosis and treatment in older people present a challenge. Applying evidence to elderly patients can be problematic, because older persons with frailty, multiple comorbidities, and functional disabilities are generally excluded from diabetes clinical trials. Frailty is characterized by multisystem decline and vulnerability to adverse health outcomes. Insulin resistance predicts frailty, and DM accelerates muscle strength loss. Geriatric diabetes care guidelines have refocused from risk factor control to geriatric syndromes. The European Diabetes Working Party guidelines for elderly type 2 DM patients consider frailty, recommending a conservative target (hemoglobin A1c <8%). Diabetic care-home residents with physical disabilities, cognitive impairment, tube feeding, and the inability to communicate pose particular challenges. Tight glycemic control for such patients increases the risk of hypoglycemia and significant functional decline; a mean hemoglobin A1c <7% did not protect them from care-home-acquired pneumonia. In conclusion, caring for elderly diabetic patients poses unique challenges. Little is known about diabetes care of elderly people with frailty, disabilities, or multiple comorbidities. The interrelationship between frailty and DM deserves further investigation. Practice guidelines for care-home residents with DM are needed to ensure quality of care.

Exercise and fitness are related to peripheral nervous system function in overweight adults

PURPOSE

This study examined the association between physical activity and fitness and peripheral nervous system (PNS) function in overweight and obese individuals.

METHODS

Forty nondiabetic overweight adults (mean +/- SD; age = 44 +/- 11 yr) were recruited for the study. Peroneal motor nerve and radial, sural, and medial plantar sensory nerve conductions were studied. Maximal oxygen uptake was measured in an incremental bicycle ergometer test. Physical activity was assessed by accelerometer and self-reporting. We analyzed the data using multiple stepwise linear regression models adjusted for age, height, and skin temperature.

RESULTS

VO2max predicted 17% of peroneal distal compound muscle action potential (CMAP) amplitude variation and 16% of peroneal proximal CMAP amplitude variation. Physical activity index at the age of 30 yr predicted 9% of peroneal motor nerve conduction velocity (NCV), 8% of peroneal F-wave maximum latency, 14% of medial plantar sensory latency, and 10% of medial plantar sensory NCV variation.

CONCLUSIONS

Physical activity and fitness are positively associated with PNS function and should be encouraged in overweight people.

Lipoprotein(a), inflammation, and peripheral arterial disease in a community-based sample of older men and women (the InCHIANTI study)

Lipoprotein(a) (Lp[a]) may represent an independent risk factor for peripheral arterial disease of the lower limbs (LL-PAD), but prospective data are scant. We estimated the association between baseline Lp(a) with prevalent and incident LL-PAD in older subjects from the InCHIANTI Study. LL-PAD, defined as an ankle-brachial index <0.90, was assessed at baseline and over a 6-year follow-up in a sample of 1,002 Italian subjects 60 to 96 years of age. Plasma Lp(a) and potential traditional and novel cardiovascular risk factors (including a score based on relevant inflammatory markers) were entered in multivariable models to assess their association with prevalent and incident LL-PAD. At baseline, Lp(a) concentration was directly related to the number of increased inflammatory markers (p <0.05). There were 125 (12.5%) prevalent cases of LL-PAD and 57 (8.3%) incident cases. After adjustment for potential confounders, participants in the highest quartile of the Lp(a) distribution (>/=32.9 mg/dl) were more likely to have LL-PAD compared to those in the lowest quartile (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.01 to 3.33). The association was stronger (OR 3.80, 95% CI 1.50 to 9.61) if LL-PAD was defined by harder criteria, namely an ankle-brachial index <0.70. Compared to subjects in the lowest Lp(a) quartile, those in the highest quartile showed a somewhat increased risk of incident LL-PAD (lowest quartile 7.7%, highest quartile 10.8%), but the association was not statistically significant (OR 1.52, 95% CI 0.71 to 3.22). In conclusion, Lp(a) is an independent LL-PAD correlate in the cross-sectional evaluation, but further prospective studies in larger populations, with longer follow-up and more definite LL-PAD ranking, might be needed to establish a longitudinal association.

Sensory and motor peripheral nerve function and lower-extremity quadriceps strength: the health, aging and body composition study

OBJECTIVES

To determine whether sensory and motor nerve function is associated cross-sectionally with quadriceps or ankle dorsiflexion strength in an older community-based population.

DESIGN

Cross-sectional analyses within a longitudinal cohort study.

SETTING

Two U.S. clinical sites.

PARTICIPANTS

Two thousand fifty-nine Health, Aging and Body Composition Study (Health ABC) participants (49.5% male, 36.7% black, aged 73-82) in 2000/01.

MEASUREMENTS

Quadriceps and ankle strength were measured using an isokinetic dynamometer. Sensory and motor peripheral nerve function in the legs and feet was assessed using 10-g and 1.4-g monofilaments, vibration threshold, and peroneal motor nerve conduction amplitude and velocity.

RESULTS

Monofilament insensitivity, poorest vibration threshold quartile (>60 mu), and poorest motor nerve conduction amplitude quartile (<1.7 mV) were associated with 11%, 7%, and 8% lower quadriceps strength (all P<.01), respectively, than in the best peripheral nerve function categories in adjusted linear regression models. Monofilament insensitivity and lowest amplitude quartile were both associated with 17% lower ankle strength (P<.01). Multivariate analyses were adjusted for demographic characteristics, diabetes mellitus, body composition, lifestyle factors, and chronic health conditions and included all peripheral nerve measures in the same model. Monofilament insensitivity (beta=-7.19), vibration threshold (beta=-0.097), and motor nerve conduction amplitude (beta=2.01) each contributed independently to lower quadriceps strength (all P<.01). Monofilament insensitivity (beta=-5.29) and amplitude (beta=1.17) each contributed independently to lower ankle strength (all P<.01). Neither diabetes mellitus status nor lean mass explained the associations between peripheral nerve function and strength.

CONCLUSION

Reduced sensory and motor peripheral nerve function is related to poorer lower extremity strength in older adults, suggesting a mechanism for the relationship with lower extremity disability.

The 9p21 myocardial infarction risk allele increases risk of peripheral artery disease in older people

BACKGROUND

A common variant at chromosome 9p21 (tagged by the rs1333049 or rs10757278 single-nucleotide polymorphism) is strongly associated with myocardial infarction and major arterial aneurysms. An association with peripheral arterial disease (PAD) was also reported in a sample younger than 75 years, but this disappeared on removal of respondents with a myocardial infarction history, resulting in an odds ratio of 1.09 for PAD (P=0.075). We aimed at estimating the association of this variant with an Ankle-Brachial Index (ABI) and PAD in 3 older populations.

METHODS AND RESULTS

We used data from the InCHIANTI, Baltimore Longitudinal Study of Aging, and Health, Aging, and Body Composition studies. In 2630 white individuals (mean age, 76.4 years), the C allele at rs1333049 was associated with lower mean ABI measures and with an increased prevalence of PAD. These associations remained after removal of baseline and incident myocardial infarction cases over a 6-year follow-up for both ABI (-0.017 ABI units; 95% CI, -0.03 to -0.01; P = 1.3 x 10(-4)) and PAD (per allele odds ratio, 1.29; 95% CI, 1.06 to 1.56; P = 0.012). These associations also remained after adjustment for known atherosclerosis risk factors, including diabetes mellitus, smoking, hypercholesterolemia, and hypertension.

CONCLUSIONS

The C allele at rs1333049 is associated with an increased prevalence of PAD and lower mean ABI. This association was independent of the presence of diagnosed myocardial infarction and atherosclerotic risk factors in 3 older white populations.

Uric acid and dementia in community-dwelling older persons

BACKGROUND

The biological action of uric acid (UA) in humans is controversial. UA is considered an antioxidant compound, but preclinical evidence suggests a proinflammatory action. Epidemiological studies found that hyperuricemia is associated with conditions leading to dementia. Our aim is to investigate the relationship between UA levels and dementia in older persons.

METHODS

Cross-sectional study performed in 1,016 community-dwelling older persons participating in the InCHIANTI study. Participants underwent determination of circulating UA levels and neuropsychological evaluation. A multivariate logistic regression model was used to estimate the probability of participants belonging to the highest and middle UA tertile to be affected by dementia compared to those in the lowest tertile.

RESULTS

Demented persons had higher UA levels (p = 0.001) and the prevalence of persons affected by dementia increased across UA tertiles (p < 0.0001). Independent of several confounders, persons belonging to the highest UA tertile had a threefold (OR = 3.32; 95% CI: 1.06-10.42) higher probability to suffer from a dementia syndrome while those in the middle UA tertile tended to have a higher probability of being demented compared to those in the lowest tertile.

CONCLUSION

In a population-based sample, high circulating UA levels are associated with an increased likelihood to be affected by a dementia syndrome.

Physical activity during daily life and circulating biomarker levels in patients with peripheral arterial disease

Higher levels of inflammation are associated with adverse outcomes in patients with lower extremity peripheral arterial disease (PAD). This study evaluated associations of physical activity during daily life with levels of inflammatory biomarkers, D-dimer, and homocysteine in patients with PAD. Participants were 244 men and women (mean age 74.4 +/- 8.2 years) with PAD (ankle brachial index <0.90). C-reactive protein, interleukin-6, soluble intracellular adhesion molecule-1, soluble vascular cellular adhesion molecule-1, D-dimer, and homocysteine were assessed at study entry. Physical activity was objectively assessed with a vertical accelerometer, which participants wore continuously for 7 days. After adjusting for age, gender, race, body mass index, smoking, co-morbidities, ankle brachial index, and other potential confounders, higher physical activity levels were associated linearly and significantly with lower levels of all measured circulating biomarkers: soluble vascular cellular adhesion molecule-1 (p trend = 0.001), D-dimer (p trend = 0.005), homocysteine (p trend = 0.006), interleukin-6 (p trend = 0.010), C-reactive protein (p trend = 0.028), and soluble intracellular adhesion molecule-1 (p trend = 0.033). In conclusion, higher levels of physical activity were associated independently with lower levels of inflammatory markers, homocysteine, and D-dimer in patients with PAD.

Mobility limitation in self-described well-functioning older adults: importance of endurance walk testing

BACKGROUND

Mobility limitations are prevalent, potentially reversible precursors to mobility loss that may go undetected in older adults. This study evaluates standardized administration of an endurance walk test for identifying unrecognized and impending mobility limitation in community elders.

METHODS

Men and women (1480 and 1576, respectively) aged 70-79 years with no reported mobility limitation participating in the Health, Aging and Body Composition study were administered the Long Distance Corridor Walk. Walk performance was examined to determine unrecognized mobility deficits at baseline and predict new self-recognition of mobility limitation within 2 years.

RESULTS

On testing, 23% and 36% of men and women evidenced mobility deficits defined as a contraindication to exertion, meeting stopping criteria or exceeding 7 minutes to walk 400 m. Unrecognized deficits increased with age and were more prevalent in blacks, smokers, obese individuals, and infrequent walkers. Within 2 years, 21% and 34% of men and women developed newly recognized mobility limitation; those with baseline unrecognized deficits had higher rates, 40% and 54% (p <.001), respectively. For each additional 30 seconds over 5 minutes needed to walk 400 m, likelihood of newly recognized mobility limitation increased by 65% and 37% in men and women independent of age, race, obesity, smoking status, habitual walking, reported walking ease, and usual gait speed.

CONCLUSIONS

A sizable proportion of elders who report no walking difficulty have observable deficits in walking performance that precede and predict their recognition of mobility limitation. Endurance walk testing can help identify these deficits and provide the basis for treatment to delay progression of mobility loss.

The relationship of reduced peripheral nerve function and diabetes with physical performance in older white and black adults: the Health, Aging, and Body Composition (Health ABC) study

OBJECTIVE

Poor peripheral nerve function is prevalent in diabetes and older populations, and it has great potential to contribute to poor physical performance.

RESEARCH DESIGN AND METHODS

Cross-sectional analyses were done for the Health, Aging, and Body Composition (Health ABC) Study participants (n = 2,364; 48% men; 38% black; aged 73-82 years). Sensory and motor peripheral nerve function in legs/feet was assessed by 10- and 1.4-g monofilament perception, vibration detection, and peroneal motor nerve conduction amplitude and velocity. The Health ABC lower-extremity performance battery was a supplemented version of the Established Populations for the Epidemiologic Studies of the Elderly battery (chair stands, standing balance, and 6-m walk), adding increased stand duration, single foot stand, and narrow walk.

RESULTS

Diabetic participants had fewer chair stands (0.34 vs. 0.36 stands/s), shorter standing balance time (0.69 vs. 0.75 ratio), slower usual walking speed (1.11 vs. 1.14 m/s), slower narrow walking speed (0.80 vs. 0.90 m/s), and lower performance battery score (6.43 vs. 6.93) (all P < 0.05). Peripheral nerve function was associated with each physical performance measure independently. After addition of peripheral nerve function in fully adjusted models, diabetes remained significantly related to a lower performance battery score and slower narrow walking speed but not to chair stands, standing balance, or usual walking speed.

CONCLUSIONS

Poor peripheral nerve function accounts for a portion of worse physical performance in diabetes and may be directly associated with physical performance in older diabetic and nondiabetic adults. The impact of peripheral nerve function on incident disability should be evaluated in older adults.

Avaliação da reprodutibilidade de testes funcionais na doença arterial periférica

Este estudo visou avaliar a reprodutibilidade de dois testes funcionais de membros inferiores em pacientes com doença arterial periférica. Os testes senta-levanta da cadeira (TSL) e da ponta do pé (TPP) foram aplicados duas vezes em 14 voluntários com doença arterial periférica por três examinadores, com intervalo de 1 minuto entre os testes e de 15 minutos entre teste e reteste. A maioria dos participantes apresentou dificuldades no TPP, sendo realizadas adaptações. Os dados foram analisados estatisticamente; o grau de concordância entre examinadores foi estimado pelo coeficiente de correlação intraclasse (CCI), sendo ±<5% considerado significativo. Todas as correlações foram estatisticamente significativas. O TSL apresentou alta reprodutibilidade tanto inter-examinador (CCI=0,904 no teste e 0,857 no reteste) quanto intra- examinador. O mesmo ocorreu com o TPP (CCI=0,824 no teste e 0,941 no reteste, na avaliação inter-examinador). A correlação de Pearson entre as médias dos três examinadores no TSL e no TPP foi 0,651 no teste e 0,609 no reteste. Ambos os testes são pois reprodutíveis e viáveis na prática clínica, mas é necessário avaliar se são sensíveis a alterações que ocorram durante o processo natural da doença ou se podem ser instrumentos viáveis para acompanhamento desses pacientes.

Diabetic neuropathy in older adults

Diabetic neuropathy is a heterogeneous disease with diverse pathology. Recognition of the clinical homolog of these pathologic processes is necessary in achieving appropriate intervention. Treatment should be individualized so the particular manifestation and underlying pathogenesis of each patient's clinical presentation are considered. In older adults, special care should be taken to manage pain while optimizing daily function and mobility, with the fewest adverse medication side effects. Older adults are at great risk for falling and fractures because of instability and weakness, and require strength exercises and coordination training. Ultimately agents that address large fiber dysfunction will be essential to reduce the gross impairment of quality of life and activities of daily living that neuropathy visits older people who have diabetes.

Ankle brachial index combined with Framingham Risk Score to predict cardiovascular events and mortality: a meta-analysis

CONTEXT

Prediction models to identify healthy individuals at high risk of cardiovascular disease have limited accuracy. A low ankle brachial index (ABI) is an indicator of atherosclerosis and has the potential to improve prediction.

OBJECTIVE

To determine if the ABI provides information on the risk of cardiovascular events and mortality independently of the Framingham risk score (FRS) and can improve risk prediction.

DATA SOURCES

Relevant studies were identified. A search of MEDLINE (1950 to February 2008) and EMBASE (1980 to February 2008) was conducted using common text words for the term ankle brachial index combined with text words and Medical Subject Headings to capture prospective cohort designs. Review of reference lists and conference proceedings, and correspondence with experts was conducted to identify additional published and unpublished studies.

STUDY SELECTION

Studies were included if participants were derived from a general population, ABI was measured at baseline, and individuals were followed up to detect total and cardiovascular mortality.

DATA EXTRACTION

Prespecified data on individuals in each selected study were extracted into a combined data set and an individual participant data meta-analysis was conducted on individuals who had no previous history of coronary heart disease.

RESULTS

Sixteen population cohort studies fulfilling the inclusion criteria were included. During 480,325 person-years of follow-up of 24,955 men and 23,339 women, the risk of death by ABI had a reverse J-shaped distribution with a normal (low risk) ABI of 1.11 to 1.40. The 10-year cardiovascular mortality in men with a low ABI (< or = 0.90) was 18.7% (95% confidence interval [CI], 13.3%-24.1%) and with normal ABI (1.11-1.40) was 4.4% (95% CI, 3.2%-5.7%) (hazard ratio [HR], 4.2; 95% CI, 3.3-5.4). Corresponding mortalities in women were 12.6% (95% CI, 6.2%-19.0%) and 4.1% (95% CI, 2.2%-6.1%) (HR, 3.5; 95% CI, 2.4-5.1). The HRs remained elevated after adjusting for FRS (2.9 [95% CI, 2.3-3.7] for men vs 3.0 [95% CI, 2.0-4.4] for women). A low ABI (< or = 0.90) was associated with approximately twice the 10-year total mortality, cardiovascular mortality, and major coronary event rate compared with the overall rate in each FRS category. Inclusion of the ABI in cardiovascular risk stratification using the FRS would result in reclassification of the risk category and modification of treatment recommendations in approximately 19% of men and 36% of women.

CONCLUSION

Measurement of the ABI may improve the accuracy of cardiovascular risk prediction beyond the FRS.

Asymptomatic peripheral arterial disease is associated with more adverse lower extremity characteristics than intermittent claudication

BACKGROUND

This study assessed functional performance, calf muscle characteristics, peripheral nerve function, and quality of life in asymptomatic persons with peripheral arterial disease (PAD).

METHODS AND RESULTS

PAD participants (n=465) had an ankle brachial index <0.90. Non-PAD participants (n=292) had an ankle brachial index of 0.90 to 1.30. PAD participants were categorized into leg symptom groups including intermittent claudication (n=215) and always asymptomatic (participants who never experienced exertional leg pain, even during the 6-minute walk; n=72). Calf muscle was measured with computed tomography. Analyses were adjusted for age, sex, race, ankle brachial index, comorbidities, and other confounders. Compared with participants with intermittent claudication, always asymptomatic PAD participants had smaller calf muscle area (4935 versus 5592 mm(2); P<0.001), higher calf muscle percent fat (16.10% versus 9.45%; P<0.001), poorer 6-minute walk performance (966 versus 1129 ft; P=0.0002), slower usual-paced walking speed (P=0.0019), slower fast-paced walking speed (P<0.001), and a poorer Short-Form 36 Physical Functioning score (P=0.016). Compared with an age-matched, sedentary, non-PAD cohort, always asymptomatic PAD participants had smaller calf muscle area (5061 versus 5895 mm(2); P=0.009), poorer 6-minute walk performance (1126 versus 1452 ft; P<0.001), and poorer Walking Impairment Questionnaire speed scores (40.87 versus 57.78; P=0.001).

CONCLUSIONS

Persons with PAD who never experience exertional leg symptoms have poorer functional performance, poorer quality of life, and more adverse calf muscle characteristics compared with persons with intermittent claudication and a sedentary, asymptomatic, age-matched group of non-PAD persons.

Incident physical disability in people with lower extremity peripheral arterial disease: the role of cardiovascular disease

OBJECTIVES

To evaluate the risk of incident physical disability and the decline in gait speed over a 6-year follow-up associated with a low ankle-arm index (AAI) in older adults.

DESIGN

Observational cohort study.

SETTING

Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Allegheny County, Pennsylvania.

PARTICIPANTS

Four thousand seven hundred five older adults, 58% women and 17.6% black, participating in the Cardiovascular Health Study.

MEASUREMENTS

AAI was measured in 1992/93 (baseline). Self-reported mobility, activity of daily living (ADL), and instrumental activity of daily living (IADL) disability and gait speed were recorded at baseline and at 1-year intervals over 6 years of follow-up. Mobility disability was defined as any difficulty walking half a mile and ADL and IADL disability was defined as any difficulty with 11 specific ADL and IADL tasks. Individuals with mobility, ADL, or IADL disability at baseline were excluded from the respective incident disability analyses.

RESULTS

Lower baseline AAI values were associated with increased risk of mobility disability and ADL/IADL disability. Clinical cardiovascular disease (CVD), diabetes mellitus, and interim CVD events partially explained these associations for mobility disability and clinical CVD and diabetes mellitus partially explained these associations for ADL and IADL disability. Individuals with an AAI less than 0.9 had on average a mean decrease in gait speed of 0.02 m/s per year, or a decline of 0.12 m/s over the 6-year follow-up. Prevalent CVD partly explained this decrease but interim CVD events did not further attenuate it.

CONCLUSION

Low AAI serves as marker of future disability risk. Reduction of disability risk in patients with a low AAI should consider cardiovascular comorbidity and the prevention of additional disabling CVD events.

Social cognitive constructs and the promotion of physical activity in patients with peripheral artery disease

PURPOSE

The purpose of this study was to provide measures and accompanying psychometric support for key constructs from social cognitive theory relevant to the promotion of physical activity in patients with peripheral artery disease (PAD).

METHODS

Patients (n = 205) were identified from 2 ongoing studies involving PAD, who completed the Geriatric Depression Scale, a 6-minute walk, and the social cognitive measures of interest: pain acceptance, self-efficacy, desire for physical competence, perceived control for walking, and satisfaction with function. Psychometric support for each measure included factor analyses, test-retest reliability, and an evaluation of construct validity by investigating how each measure was related to depression and performance on the 6-minute walk test.

RESULTS

The measures of interest had good structural integrity, were reliable, and shared expected variance with depressed affect; most had significant linear trends with the 6-minute walk test, suggesting that compromised psychological status is related to poorer mobility.

CONCLUSIONS

Constructs from social cognitive theory are clearly relevant to the promotion of physical activity in PAD patients. To this end, this study offers measures of relevant constructs that can now be implemented into intervention research.

Associations between lower extremity ischemia, upper and lower extremity strength, and functional impairment with peripheral arterial disease

OBJECTIVES

To identify associations between lower extremity ischemia and leg strength, leg power, and hand grip in persons with and without lower extremity peripheral arterial disease (PAD). To determine whether poorer strength may mediate poorer lower extremity performance in persons with lower arterial brachial index (ABI) levels.

DESIGN

Cross-sectional.

SETTING

Academic medical centers.

PARTICIPANTS

Four hundred twenty-four persons with PAD and 271 without PAD.

MEASUREMENTS

Isometric knee extension and plantarflexion strength and handgrip strength were measured using a computer-linked strength chair. Knee extension power was measured using the Nottingham leg rig. ABI, 6-minute walk, and usual and fastest 4-m walking velocity were measured. Results were adjusted for potential confounders.

RESULTS

Lower ABI values were associated with lower plantarflexion strength (P trend=.04) and lower knee extension power (P trend <.001). There were no significant associations between ABI and handgrip or knee extension isometric strength. Significant associations between ABI and measures of lower extremity performance were attenuated after additional adjustment for measures of strength.

CONCLUSION

These results are consistent with the hypothesis that lower extremity ischemia impairs strength specifically in distal lower extremity muscles. Associations between lower extremity ischemia and impaired lower extremity strength may mediate associations between lower ABI values and greater functional impairment.

The myopathy of peripheral arterial occlusive disease: part 1. Functional and histomorphological changes and evidence for mitochondrial dysfunction

In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease (PAD). These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in PAD patients and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, we highlight the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy. In part 1, the authors review the functional and histomorphological characteristics of the myopathy and focus on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, they then review accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of PAD myopathy. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.

The interplay between uric acid and antioxidants in relation to physical function in older persons

OBJECTIVES

To investigate the relationship between circulating uric acid (UA) levels and plasma antioxidants and whether antioxidant levels modulate the association between UA and physical function.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

Nine hundred sixty-six elderly persons participating in the baseline assessment of the Invecchiare in Chianti Study.

MEASUREMENTS

UA, carotenoid, tocopherol, and selenium concentrations were assayed. Physical function was measured using the Short Physical Performance Battery (SPPB) and difficulties in instrumental activities of daily living (IADLs). Potential confounders were assessed using standardized methods.

RESULTS

Total carotenoids (P=.008), in particular alpha-carotene (P=.02), lutein (P<.001), zeaxanthin (P<.001), lycopene (P=.07), cryptoxanthin (P=.29), and selenium (P=.04) were inversely associated with UA levels. Total tocopherols (P=.06) and alpha-tocopherol (P=.10) had a positive trend across UA levels. SPPB (P=.01) and IADL disability (P=.002) were nonlinearly distributed across the UA quintiles. Participants within the middle UA quintile (4.8-5.3 mg/dL) were less disabled in IADLs and had better SPPB scores than those in the extreme UA quintiles. There was a significant interaction between UA and selenium in the model predicting SPPB score (P=.02).

CONCLUSION

UA levels are inversely associated with circulating carotenoids and selenium. Participants with intermediate UA levels had a higher prevalence of good physical functions, higher SPPB scores, and lower IADL disability. This study suggests that older subjects with intermediate UA levels may have an optimum balance between proinflammatory and antioxidant compounds that may contribute to better physical performance.

Exercícios resistidos terapêuticos para indivíduos com doença arterial obstrutiva periférica: evidências para a prescrição

A prática regular de exercícios é parte do tratamento clínico inicial para pacientes com doença arterial obstrutiva periférica. Nesse sentido, a utilização de exercícios contra resistência (exercícios resistidos) tem sido amplamente recomendada para diferentes populações, especialmente para pessoas idosas com e sem doenças associadas. Os poucos trabalhos encontrados utilizando essa forma de exercícios em pacientes com doença arterial obstrutiva periférica documentam a sua eficiência terapêutica. No entanto, os efeitos documentados dos exercícios resistidos em outras populações têm evidenciado melhoria da aptidão física e da qualidade de vida, com segurança cardiovascular e músculo-esquelética. Essas informações fornecem indicativos sobre os possíveis benefícios dos exercícios resistidos na terapia de indivíduos com doença arterial obstrutiva periférica. Nesse sentido, esta revisão objetivou apresentar informações científicas que permitam auxiliar a prescrição dos exercícios resistidos para essa população.

Prevalence of lower extremity diseases associated with normal glucose levels, impaired fasting glucose, and diabetes among U.S. adults aged 40 or older

BACKGROUND

Peripheral arterial disease (PAD) and peripheral neuropathy (PN) are serious complications of diabetes, but early detection and intervention may reduce this morbidity. The degree to which PAD and PN develop before diabetes diagnosis has not been established among a representative sample of U.S. adults.

OBJECTIVE

To compare the prevalence of lower extremity diseases (LEDs) among U.S. adults aged 40 or older with previously diagnosed diabetes, undiagnosed diabetes, impaired fasting glucose, and normal glucose levels.

RESEARCH DESIGN AND METHODS

We analyzed cross-sectional data of a nationally representative sample of 3607 U.S. adults from the 1999-2004 National Health and Nutrition Examination Surveys (NHANES). Subjects were divided into four groups on the basis of their fasting plasma glucose (FPG) levels and interview responses: normal glucose levels (FPG<100mg/dl), impaired fasting glucose (IFG; FPG 100-125 mg/dl), undiagnosed diabetes (FPG> or =126 and no self-reported diabetes), and diagnosed diabetes. PN was assessed by monofilament testing at three sites on each foot and defined as > or =1 insensate area. PAD was defined as an ankle-brachial blood pressure index <0.9. Any LED was defined as the presence of PAD or PN or a history of non-healing ulcer or amputation.

RESULTS

The prevalence of PN was lowest among persons with normal glucose (10.5%) and IFG (11.9%) and highest among those with undiagnosed (16.6%) and diagnosed diabetes (19.4%). PAD prevalence was also lowest among persons with normal glucose (3.9%), similar among those with IFG (5.4%), and significantly higher among those with undiagnosed (9.2%) and diagnosed diabetes (7.5%). Any LED was present in about 27% of persons with both undiagnosed diabetes and diagnosed diabetes.

CONCLUSIONS

LED prevalence was nearly as high among persons with previously undiagnosed diabetes as among those with diagnosed diabetes, but it was not appreciably higher among persons with impaired fasting glucose than among those with normal glucose levels. These results suggest that LED detection efforts should be focused on persons with diabetes, including those with undiagnosed diabetes.

Elevated levels of inflammation, d-dimer, and homocysteine are associated with adverse calf muscle characteristics and reduced calf strength in peripheral arterial disease

OBJECTIVES

This study determined whether increased levels of inflammatory blood markers, D-dimer, and homocysteine were associated with smaller calf skeletal muscle area, increased calf muscle percent fat, reduced calf muscle density, and poorer calf strength in persons with lower extremity peripheral arterial disease (PAD).

BACKGROUND

Elevated levels of inflammatory markers and D-dimer are associated with greater functional impairment and functional decline in persons with PAD. Mechanisms of these associations are unknown.

METHODS

Participants were 423 persons with PAD. Calf muscle area, percent fat, and density were measured with computed tomography. Physical activity levels were measured objectively over 7 days with the Caltrac (Muscle Dynamics Fitness Network, Inc., Rocklin, California) vertical accelerometer. Isometric plantarflexion strength was measured. Analyses were adjusted for age, gender, race, comorbidities, the ankle-brachial index, and other potential confounders.

RESULTS

Higher levels of D-dimer (p = 0.014), C-reactive protein (CRP) (p = 0.002), interleukin (IL)-6 (p < 0.001), and soluble vascular cellular adhesion molecule (sVCAM)-1 (p = 0.008) were associated with smaller calf muscle area. Higher sVCAM-1 (p = 0.004) and IL-6 (p = 0.017) were associated with higher calf muscle percent fat. Higher D-dimer (p < 0.001), sVCAM-1 (p < 0.001), and homocysteine (p = 0.014) were associated with lower calf muscle density. These associations were generally unchanged after additional adjustment for physical activity. Higher sVCAM-1 (p = 0.013) was associated with lower calf strength.

CONCLUSIONS

These data show, for the first time, that higher levels of inflammation, D-dimer, and homocysteine are associated with more adverse calf muscle characteristics in persons with PAD. These associations may contribute to previously established associations between elevated biomarkers and functional impairment and functional decline in PAD.

Usefulness of uric acid to predict changes in C-reactive protein and interleukin-6 in 3-year period in Italians aged 21 to 98 years

The role of uric acid (UA) in the process of atherothrombosis is controversial. Although serum UA has powerful antioxidant properties, epidemiological studies showed that UA was a risk factor for cardiovascular diseases and was positively associated with proinflammatory markers. Relations between baseline UA and changes in UA circulating levels with C-reactive protein (CRP) and interleukin-6 (IL-6) after 3 years of follow-up in a cohort of 892 Italian men and women aged 21 to 98 years was investigated. Subjects had complete baseline and follow-up data for UA, inflammatory markers, and covariates. An autoregressive approach was used to study such a relation. In adjusted analyses, baseline UA and changes in UA predicted a 3-year change in CRP (p = 0.028), but not IL-6 (p = 0.101). The relation between UA and CRP persisted after adjustment for baseline IL-6. Subjects with high UA at baseline had a progressively higher probability of developing clinically relevant increased IL-6 (>2.5 pg/ml) and CRP (>3 mg/L) during 3 years. In conclusion, our study suggests that in a population-based cohort, baseline UA and changes in circulating UA during 3 years of follow-up predict changes in circulating CRP independent of relevant confounders, including baseline IL-6.

Effects of Alpha-Lipoic Acid Supplementation in Peripheral Arterial Disease: A Pilot Study

OBJECTIVE

To examine whether 3 months of lipoic acid (LA) supplementation improved walking tolerance and delayed claudication pain onset in peripheral arterial disease (PAD).

DESIGN

Randomized, double-blind, controlled study.

SETTING

General Clinical Research Center.

SUBJECTS

Twenty-eight (28) participants (15 men, 13 women) with PAD (ankle brachial index range 0.9-0.4, mean age 73.2 +/- 1.6 years).

INTERVENTION

LA (600 mg/day) or placebo for 3 months.

OUTCOME MEASURES

Walking tolerance was assessed by 6-minute walk test distance, 4-meter walk time, initial claudication pain time (ICT) and distance (ICD), and peak claudication pain. Serum was assessed for inflammation (C-reactive protein [CRP]) and oxidative stress (lipid hydroperoxides) as potential mechanisms for changes in walking tolerance.

RESULTS

ICT increased 34.4% and 15%, ICD was reduced by 40.5% and 18%, and peak claudication pain ratings were reduced by 93% and 7% in LA and placebo groups, respectively. Although the improvements in peak pain and ICT achieved significance within the LA group (both p<0.05), the interactions of group by time were not found to be significant (p>0.05). Oxidative stress and CRP measures were not different between groups by month 3 (p>0.05). There were no serious side-effects associated with the LA.

CONCLUSIONS

LA may confer pain relief during exercise. However, longer and larger trials are warranted to determine long-term effects of LA alone or combined with other interventions on PAD symptoms.

Physical activity, walking exercise, and calf skeletal muscle characteristics in patients with peripheral arterial disease

OBJECTIVE

This cross-sectional study was set in an academic medical center and conducted to identify associations of physical activity level and walking exercise frequency with calf skeletal muscle characteristics in individuals with lower extremity peripheral arterial disease (PAD).

METHODS

Calf muscle characteristics in 439 men and women with PAD were measured with computed tomography at 66.67% of the distance between the distal and proximal tibia. Physical activity was measured continuously during 7 days with a vertical accelerometer. Patient report was used to determine the number of blocks walked during the past week and walking exercise frequency. Results were adjusted for age, sex, race, comorbidities, ankle-brachial index, body mass index, smoking, and other confounders.

RESULTS

For both objective and subjective measures, more physically active PAD participants had higher calf muscle area and muscle density. Calf muscle area across tertiles of accelerometer-measured physical activity were first activity tertile, 5071 mm(2); second activity tertile: 5612 mm(2); and third activity tertile, 5869 mm(2) (P < .001). Calf muscle density across tertiles of patient-reported blocks walked during the past week were first activity tertile, 31.4 mg/cm(3); second activity tertile, 33.0 mg/cm(3); and third activity tertile, 33.8 mg/cm(3) (P < .001). No significant associations were found between walking exercise frequency and calf muscle characteristics.

CONCLUSION

Among participants with PAD, higher physical activity levels, measured by accelerometer and by patient-reported blocks walked per week, were associated with more favorable calf muscle characteristics. In contrast, more frequent patient-reported walking exercise was not associated with more or less favorable calf muscle characteristics. Results suggest that clinicians should encourage their patients to increase their walking activity during daily life.

Lower extremity ischemia, calf skeletal muscle characteristics, and functional impairment in peripheral arterial disease

OBJECTIVES

To determine whether lower ankle brachial index (ABI) levels are associated with lower calf skeletal muscle area and higher calf muscle percentage fat in persons with and without lower extremity peripheral arterial disease (PAD).

DESIGN

Cross-sectional.

SETTING

Three Chicago-area medical centers.

PARTICIPANTS

Four hundred thirty-nine persons with PAD (ABI<0.90) and 265 without PAD (ABI 0.90-1.30).

MEASUREMENTS

Calf muscle cross-sectional area and the percentage of fat in calf muscle were measured using computed tomography at 66.7% of the distance between the distal and proximal tibia. Physical activity was measured using an accelerometer. Functional measures included the 6-minute walk, 4-meter walking speed, and the Short Physical Performance Battery (SPPB).

RESULTS

Adjusting for age, sex, race, comorbidities, and other potential confounders, lower ABI values were associated with lower calf muscle area (ABI<0.50, 5,193 mm(2); ABI 0.50-0.90, 5,536 mm(2); ABI 0.91-1.30, 5,941 mm(2); P for trend<.001). These significant associations remained after additional adjustment for physical activity. In participants with PAD, lower calf muscle area in the leg with higher ABI was associated with significantly poorer performance in usual- and fast-paced 4-meter walking speed and on the SPPB, adjusting for ABI, physical activity, percentage fat in calf muscle, muscle area in the leg with lower ABI, and other confounders (P<.05 for all comparisons).

CONCLUSION

These data support the hypothesis that lower extremity ischemia has a direct adverse effect on calf skeletal muscle area. This association may mediate previously established relationships between PAD and functional impairment.

Reduced peripheral nerve function is related to lower hip BMD and calcaneal QUS in older white and black adults: the Health, Aging, and Body Composition Study

Bone tissue is innervated, and peripheral nerve function may impact BMD. Older black and white men and women (N = 2200) in the Health, Aging, and Body Composition Study with worse sensory and motor peripheral nerve function had lower hip BMD and calcaneal BUA independent of lean mass, strength, physical ability, and diabetes. Poor peripheral nerve function may directly affect bone.

INTRODUCTION

Bone tissue is innervated, yet little is known about the impact of nerve function on BMD. Poor peripheral nerve function may contribute to lower BMD and higher fracture risk, particularly in those with diabetic neuropathy.

MATERIALS AND METHODS

The Health, Aging, and Body Composition (Health ABC) Study included annual exams in white and black men and women 70-79 years of age recruited from Pittsburgh and Memphis. Nerve function in legs/feet was assessed by 1.4- and 10-g monofilament detection, vibration threshold, and peroneal motor nerve conduction velocity (NCV) and amplitude (CMAP). Total hip BMD, heel broadband ultrasound attenuation (BUA), and total fat and lean mass were measured 1 year later (QDR 4500A, Sahara QUS; Hologic).

RESULTS

Participants (N = 2200) were 48% men and 37% black. Poor nerve function (lower monofilament detection, higher vibration threshold, lower CMAP, lower NCV) was associated with 1.4-5.7% lower BUA and significant for all but NCV, adjusted for demographics, diabetes, body composition, and physical ability. Results were similar for adjusted hip BMD, with 1.0-2.9% lower BMD, significant for monofilament and CMAP testing. When considering the components of BMD, total hip area was 1.8-4.9% higher in those with the worst nerve function, although BMC showed little difference. Lower monofilament detection and CMAP were independently associated with lower heel BUA (p < 0.01), and monofilament detection was associated with lower hip BMD (p < 0.05) in regression additionally adjusted for lifestyle factors, bone-active medications, and diabetes-related complications.

CONCLUSIONS

Poor peripheral nerve function may directly related to lower BMD, likely through an increase in bone area in older adults, independent of lean mass, strength, physical ability, and diabetes. Whether those with impaired nerve function are at higher risk for fracture independent of falls needs to be studied.

Predictive Role of Single Diseases and Their Combination on Recovery of Balance and Gait in Disabled Elderly Patients

OBJECTIVES

In the elderly population, chronic diseases are common determinants of mobility limitations and comorbidity consistently shows a strong association with functional status. This study was designed to evaluate the role of single chronic diseases and of their combination on functional recovery after rehabilitative treatment in disabled elderly patients.

DESIGN

With respect to the difference in magnitude of their disabling effect, diseases were classified into 2 groups: "more disabling" diseases (COPD, heart failure, peripheral artery diseases, diabetes, and not life-threatening cancer) and "less disabling" diseases (anemia, kidney, gastrointestinal, and liver diseases).

SETTING

35-bed Geriatric Evaluation and Rehabilitation Unit.

PARTICIPANTS

We studied 710 patients (age 77.8 +/- 7.4 years, 76.2% females), consecutively admitted for stroke, Parkinson's disease, and osteoarthritis.

MEASUREMENTS

A multidimensional evaluation for mobility (Tinetti-score), cognitive status (MMSE), and somatic health (Greenfield's Individual Disease Severity Index-IDS, Burden of diseases-BoD) was performed. Functional recovery was decided based on the Delta-Tinetti, which is the difference of the values between admission and discharge.

RESULTS

We tested, in a multivariate regression model, the predictive role of single chronic conditions and of their combinations on functional recovery, after having adjusted for which diseases are direct causes of disability (stroke, Parkinson's disease, and osteoarthritis) and other potential predictors (age, sex, cognitive function, depressive symptoms, albumin, and c-reactive protein). A negative prediction of functional recovery was expressed by the "more disabling" diseases group. The determinants of poor recovery were characterized by the combination of "more disabling diseases" rather than single condition effects, independently by age, cognitive, and functional status on admission.

CONCLUSION

Our study adds a new perspective about the role of COPD, heart failure, peripheral artery diseases, diabetes and not life-threatening cancer on functional recovery, emphasizing their combined impact in elderly people.

Uric acid and inflammatory markers

AIMS

The role of uric acid (UA) in the process of atherosclerosis and atherotrombosis is controversial. Epidemiological studies have recently shown that UA may be a risk factor for cardiovascular diseases and a negative prognostic marker for mortality in subjects with pre-existing heart failure.

METHODS AND RESULTS

We evaluate a relationship between UA levels and several inflammatory markers in 957 subjects, free of severe renal failure, from a representative Italian cohort of persons aged 65-95. Plasma levels of UA and white blood cell (WBC) and neutrophil count, C-reactive protein, interleukin-1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6r), interleukin-18 (IL-18), and tumor necrosis factor-alpha (TNF-alpha) were measured. Complete information on potential confounders was collected using standard methods. WBC (P=0.0001), neutrophils (P<0.0001), C-reactive protein (P<0.0001), IL-1ra (P<0.0001), IL-6 (P=0.0004), sIL-6r (P=0.002), IL-18 (P<0.0001), TNF-alpha (P=0.0008), and the percentage of subjects with abnormally high levels of C-reactive protein (P=0.004) and IL-6 (P=<0.0001) were significantly higher across UA quintiles. After adjustment for age, sex, behaviour- and disease-related confounders, results were virtually unchanged. In subjects with UA within the normal range, UA was significantly and independently associated with neutrophils count, C-reactive protein, IL-6, IL-1ra, IL-18, and TNF-alpha, whereas non-significant trends were observed for WBC (P=0.1) and sIL-6r (P=0.2).

CONCLUSION

A positive and significant association between UA and several inflammatory markers was found in a large population-based sample of older persons and in a sub-sample of participants with normal UA. Accordingly, the prevalence of abnormally high levels of C-reactive protein and IL-6 increased significantly across UA quintiles.

Low socioeconomic status and disability in old age: evidence from the InChianti study for the mediating role of physiological impairments

BACKGROUND

Low socioeconomic status (SES) has been associated with increased risk of disability in later life. The purpose of this study was to determine if SES has an impact on mobility functioning and to explore which physiological impairments are also associated with SES and may explain its relationship with mobility.

METHODS

The study sample consisted of 1025 individuals aged 65 years or older residing in the Chianti area (Italy). Number of years of education was used as an indicator of SES. Mobility functioning was assessed using gait speed (400 m) and the Short Physical Performance Battery (SPPB). Mobility-related physiological impairments were assessed with tests of executive functioning, nerve conduction velocity, muscle power, hip-ankle range of motion, Ankle-Brachial Index, and visual acuity. Linear regression models were used to study the association between number of years of education and mobility and to estimate the contribution of each of the selected physiological impairments to this association.

RESULTS

Adjusting for age and sex, slower gait speed (1.16 vs 1.26 m/s, p <.0001) and lower SPPB scores (9.55 vs 10.11, p =.006) were seen in persons with < or =5 years of total education compared with those persons with >5 years of total education. Leg power and executive function decreased the strength of the association between educational level and gait speed by more than 15%. Controlling for all selected impairments (full model) decreased the education-gait speed association by 49%. Low education continued to be significantly associated with gait speed (p <.01). Adjusting for all physiological impairments substantially reduced the low education-SPPB score association by 100%, and this association was no longer significant.

CONCLUSIONS

Low SES is related to multiple physiological impairments, which explain a large amount of the association between education and gait limitations. Further work must be done to understand the mechanisms whereby low SES translates into the impairments that play an important role in mobility.