Walking performance in individuals with lumbar spinal stenosis-possible outcome measures and assessment of known-group validity.

BACKGROUND CONTEXT: One of the primary goals of treatments received by individuals with lumbar spinal stenosis with neurogenic claudication is to improve walking ability. Thus, a thorough and valid assessment of walking ability in patients with lumbar spinal stenosis is needed. Duration of continuous walking and steps per day could be relevant when evaluating walking ability in daily living. PURPOSE: To describe and evaluate a method for estimating continuous walking periods in daily living and to evaluate the known-group validity of steps per day in individuals with lumbar spinal stenosis. STUDY DESIGN: This is a cross-sectional observational study. PATIENT SAMPLE: The study contains three study groups: individuals with lumbar spinal stenosis, individuals with low back pain, and a background population from the Lolland-Falster Health Study (LOFUS). OUTCOME MEASURES: Participants in all three study groups wore an accelerometer on the thigh for seven days. METHODS: Accelerometer data were processed to summarize the continuous walking periods according to their length: the number of short (4-9 seconds), moderate (10-89 seconds), and extended (≥90 seconds) continuous walking periods per day, and the number of steps per day. Results from the three groups were compared using negative binomial regression with lumbar spinal stenosis as the reference level. RESULTS: Continuous walking periods of moderate length were observed 1.48 (95% CI 1.27, 1.72) times more often in individuals from the background population than in individuals with LSS. Continuous walking periods of extended length were observed 1.53 (95% CI 1.13, 2.06) times more often by individuals with low back pain and 1.60 (95% CI 1.29, 1.99) times more often by individuals from the background population. The number of steps per day was 1.22 (95% CI 1.03, 1.46) times larger in individuals with LBP and 1.35 (95% CI 1.20, 1.53) times larger in individuals from background population. CONCLUSIONS: The impact of neurogenic claudication on walking ability in daily living seems possible to describe by continuous walking periods along with steps per day. The results support known-group validity of steps per day. This is the next step toward a clinically relevant and comprehensive assessment of walking in daily living in individuals with lumbar spinal stenosis.

Objective assessment of functional capacity in patients with peripheral artery disease: a narrative review.

INTRODUCTION: Peripheral artery disease (PAD) patients with claudication symptoms exhibit impaired functional capacity, which has been associated with disease severity, worse quality of life and higher risk of cardiovascular events. Different tests have been used to assess functional capacity in PAD patients. Therefore, understanding the characteristics, strengths and limitations of these tests are important to support the choice of tests to be used in clinical practice. AREAS COVERED: This review summarizes the main methods to assess functional capacity in PAD patients, discussing their psychometric properties, applications, and limitations. EXPERT OPINION: Robust evidence supports the use of treadmill and six-minute walk tests in PAD patients, as their results are associated with clinically meaningful outcomes, adequate psychometric properties and are sensitive to effects of interventions. On the other hand, other functional tests (Shuttle-walk test, outdoor walking capacity test, timed-up and go, four-meter walk test, heel-rise test, short physical performance battery and modified physical performance battery) are related to activities of daily living and do not require sophisticated equipment and can be easily used in clinical practice. However, these other tests still need evidence regarding their clinical relevance, reliability, and ability to detect long-term intervention changes, providing further investigation directions.

Responsiveness of the Zurich Claudication Questionnaire, the Oswestry Disability Index, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, the 8-Item Short Form Health Survey, and the Euroqol 5 dimensions 5 level in the assessment of patients with lumbar spinal stenosis.

PURPOSE: To assess the responsiveness of the Zurich Claudication Questionnaire (ZCQ), the Oswestry Disability Index, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, the visual analog scale (VAS), the 8-Item Short Form Health Survey (SF-8), and the EuroQol 5 dimensions 5 level as methods of assessing outcomes of surgery for lumbar spinal stenosis. METHODS: We analyzed 218 patients who had undergone lumbar surgery for spinal stenosis and completed one year of follow-up. The internal responsiveness of each questionnaire and any domains was assessed by the effect size and standardized response mean. External responsiveness was assessed by the Spearman rank correlation coefficient and the receiver operating characteristics (ROC) curve. RESULTS: The most responsive assessments were "symptom severity" and "physical function" on the ZCQ, "walking ability" on the JOABPEQ, "leg pain" on the VAS, and "social function" on the JOABPEQ. The moderately responsive assessments were the physical component summary on the SF-8, the ODI, the EQ5D-5L, "low back pain" on the JOABPEQ, and "leg numbness" on the VAS. The least responsive assessments were "low back pain" on the VAS, "mental health" and "lumbar function" on the JOABPEQ, and the mental component summary on the SF-8. CONCLUSIONS: Because of its high responsiveness, "symptom severity" on the ZCQ is recommended as a primary tool for assessing outcome when designing prospective studies for lumbar spinal stenosis.

Index atherectomy peripheral vascular interventions performed for claudication are associated with more reinterventions than nonatherectomy interventions.

OBJECTIVE: Despite limited evidence supporting atherectomy alone over stenting/angioplasty as the index peripheral vascular intervention (PVI), the use of atherectomy has rapidly increased in recent years. We previously identified a wide distribution of atherectomy practice patterns among US physicians. The aim of this study was to investigate the association of index atherectomy with reintervention. METHODS: We used 100% Medicare fee-for-service claims to identify all beneficiaries who underwent elective first-time femoropopliteal PVI for claudication between January 1, 2019, and December 31, 2019. Subsequent PVI reinterventions were examined through June 30, 2021. Kaplan-Meier curves were used to compare rates of PVI reinterventions for patients who received index atherectomy versus nonatherectomy procedures. Reintervention rates were also described for physicians by their overall atherectomy use (by quartile). A hierarchical Cox proportional hazard model was used to evaluate patient and physician-level characteristics associated with reinterventions. RESULTS: A total of 15,246 patients underwent an index PVI for claudication in 2019, of which 59.7% were atherectomy. After a median of 603 days (interquartile range, 77-784 days) of follow-up, 41.2% of patients underwent a PVI reintervention, including 48.9% of patients who underwent index atherectomy versus 29.8% of patients who underwent index nonatherectomy (P < .001). Patients treated by high physician users of atherectomy (quartile 4) received more reinterventions than patients treated by standard physician users (quartiles 1-3) (56.8% vs 39.6%; P < .001). After adjustment, patient factors association with PVI reintervention included receipt of index atherectomy (adjusted hazard ratio [aHR], 1.33; 95% confidence interval [CI], 1.21-1.46), Black race (vs White; aHR; 1.18; 95% CI, 1.03-1.34), diabetes (aHR, 1.13; 95% CI, 1.07-1.21), and urban residence (aHR, 1.11; 95% CI, 1.01-1.22). Physician factors associated with reintervention included male sex (aHR, 1.52; 95% CI, 1.12-2.04), high-volume PVI practices (aHR, 1.23; 95% CI, 1.10-1.37), and physicians with a high use of index atherectomy (aHR, 1.49; 95% CI, 1.27-1.74). Vascular surgeons had a lower risk of PVI reintervention than cardiologists (vs vascular; aHR, 1.22; 95% CI, 1.09-1.38), radiologists (aHR, 1.55; 95% CI, 1.31-1.83), and other specialties (aHR, 1.59; 95% CI, 1.20-2.11). The location of services delivered was not associated with reintervention (P > .05). CONCLUSIONS: The use of atherectomy as an index PVI for claudication is associated with higher PVI reintervention rates compared with nonatherectomy procedures. Similarly, high physician users of atherectomy perform more PVI reinterventions than their peers. The appropriateness of using atherectomy for initial treatment of claudication needs critical reevaluation.

Cost Effectiveness of Endovascular Revascularisation vs. Exercise Therapy for Intermittent Claudication Due to Iliac Artery Obstruction.

OBJECTIVE: To compare cost effectiveness of endovascular revascularisation (ER) and supervised exercise therapy (SET) as primary treatment for patients with intermittent claudication (IC) due to iliac artery obstruction. METHODS: Cost utility analysis from a restricted societal perspective and time horizon of 12 months. Patients were included in a multicentre randomised controlled trial (SUPER study, NCT01385774, NTR2648) which compared effectiveness of ER and SET. Health status and health related quality of life (HRQOL) were measured using the Euroqol 5 dimensions 3 levels (EQ5D-3L) and VascuQol-25-NL. Incremental costs were determined per allocated treatment and use of healthcare during follow up. Effectiveness of treatment was determined in quality adjusted life years (QALYs). The difference between treatment groups was calculated by an incremental cost utility ratio (ICER). RESULTS: Some 240 patients were included, and complete follow up was available for 206 patients (ER 111 , SET 95). The mean costs for patients allocated to ER were €4 031 and €2 179 for SET, a mean difference of €1 852 (95% bias corrected and accelerated [bca] bootstrap confidence interval 1 185 - 2 646). The difference in QALYs during follow up was 0.09 (95% bcaCI 0.04 - 0.13) in favour of ER. The ICER per QALY was €20 805 (95% bcaCI 11 053 - 45 561). The difference in VascuQol sumscore was 0.64 (95% bcaCI 0.39 - 0.91), again in favour of ER. CONCLUSION: ER as a primary treatment, results in slightly better health outcome and higher QALYs and HRQOL during 12 months of follow up. Although these differences are statistically significant, clinical relevance must be discussed due to the small differences and relatively high cost of ER as primary treatment.

Long Term Survival and Limb Salvage in Patients With Non-Revascularisable Chronic Limb Threatening Ischaemia.

OBJECTIVE: The aim of this study was to provide long term survival and limb salvage rates for patients with non-revascularisable (NR) chronic limb threatening ischaemia (CLTI). METHODS: This was a retrospective review of prospectively collected data, derived from a randomised controlled trial (JUVENTAS) investigating the use of a regenerative cell therapy. Survival and limb salvage of the index limb in CLTI patients without viable options for revascularisation at inclusion were analysed retrospectively. The primary outcome was amputation free survival, a composite of survival and limb salvage, at five years after inclusion in the original trial. RESULTS: In 150 patients with NR-CLTI, amputation free survival was 43% five years after inclusion. This outcome was driven by an equal rate of all cause mortality (35%) and amputation (33%). Amputation occurred predominantly in the first year. Furthermore, 33% of those with amputation subsequently died within the investigated period, with a median interval of 291 days. CONCLUSION: Five years after the initial need for revascularisation, about half of the CLTI patients who were deemed non-revascularisable survived with salvage of the index limb. Although the prospects for these high risk patients are still poor, under optimal medical care, amputation free survival seems comparable with that of revascularisable CLTI patients, while the major amputation rate within one year, especially among NR-CLTI patients with ischaemic tissue loss, is very high.

Revascularization of smokers with claudication is not predicted to limit quality of life despite a higher risk of late failure.

OBJECTIVE: Tobacco smoking after lower extremity revascularization for claudication has repeatedly been shown to increase the risk of adverse events, such that many vascular specialists consider that refusal to abstain from smoking constitutes a major contraindication to open surgical bypass or endovascular intervention. METHODS: A Markov decision analysis (DA) model was used to compare the options of direct revascularization vs medical therapy only in smokers with claudication. The primary outcome was calculated quality of life (cQoL), determined for each patient at follow-up based on the outcomes of the treatment received. Markov DA software was used to predict the QoL for each treatment option preoperatively based on smoking status. RESULTS: Among patients referred during a recent 64-month period with vasculogenic claudication, 94 were actively smoking compared with 217 who were not. The DA model predicted that if the patients who smoked were to discontinue smoking, the best therapy would be bypass surgery for 77% and endovascular intervention for 17%. However, despite at least doubling the risks with intervention in the patients who continue to smoke, the DA model still predicted that 78% and 9% would fare better with open surgical or endovascular intervention, respectively. Among actively smoking patients, open surgical (3%) or endovascular (4%) therapies were initially performed in few patients, whereas 93% were offered only medical therapy. Among initial nonsmokers, revascularization was performed by open (27%) or endovascular (42%) means. At 3 years, the median (interquartile range [IQR]) cQoL was lower in initial smokers than in nonsmokers (0.73 [IQR, 0.73-0.77] vs 0.82 [IQR, 0.75-0.86]; P < .0001), primarily because of a lack of revascularization for smokers. Among initial smokers who did undergo revascularization initially, because of progression of symptoms, or after smoking cessation, cQoL was similar to initial nonsmokers (0.77 [IQR, 0.73-0.84] vs 0.73 [IQR, 0.73-0.73]; P = .37). Although 26% of initial smokers had stopped by the time of their last follow-up, 10% of initially nonsmoking patients were smoking at follow-up. However, among all patients undergoing intervention, the cQoL of patients smoking at the time of last their follow-up was similar to nonsmokers (0.82 [IQR, 0.82-0.86] vs 0.83 [IQR, 0.73-0.86]; P = .99). CONCLUSIONS: Patients with claudication who smoke may be denied the symptom improvement associated with revascularization, yet recidivism for smoking also occurs among patients who have stopped smoking in order to receive revascularization. The strategy not to directly revascularize patients with claudication who continue to smoke does not appear to maximize patient midterm QoL.

Rehabilitation Therapy in Peripheral Arterial Disease.

Peripheral arterial disease (PAD) is the result of atherosclerosis in the lower limb arteries, which can give rise to intermittent claudication (IC), limb ulceration, infections, and, in some circumstances, amputation. As a result of PAD, patients are frequently limited in both walking duration and speed. These ambulatory deficits impact both functional capacity and quality of life. The prevalence of PAD is increasing, and patients with this diagnosis have high cardiovascular morbidity and mortality. A comprehensive approach is required to improve outcomes in patients with PAD and include tobacco cessation, pharmacologic management of metabolic fitness, risk-factor modification, and exercise training. Supervised exercise programs significantly improve functional capacity and quality of life in addition to reducing IC. These programs reduce morbidity and mortality and are cost-effective; yet they are uncommonly prescribed. Supervised exercise training is an accepted intervention in the PAD population and has been included in both Canadian and American guidelines for PAD management. This review describes (1) key background information related to PAD, (2) the initial approach to PAD diagnosis, (3) pharmacologic management options, (4) risk-factor modification, and (5) the currently accepted approach to exercise training. Key recommendations for enhancing PAD care in a Canadian context are also discussed.

Cost-effectiveness of cilostazol, naftidrofuryl oxalate, and pentoxifylline for the treatment of intermittent claudication in people with peripheral arterial disease.

We assessed the cost-effectiveness of cilostazol, naftidrofuryl oxalate, and pentoxifylline for intermittent claudication due to peripheral arterial disease (PAD) in adults whose symptoms continue despite a period of conventional management. A Markov decision model was developed to assess the lifetime costs and benefits of each vasoactive drug compared to no vasoactive drug and with each other. Regression analysis was undertaken to model the relationship between maximum walking distance and utility. Resource use data were sourced from the literature and sensitivity analyses were undertaken. Naftidrofuryl oxalate is more effective and less costly than cilostazol and pentoxifylline and has an estimated cost per quality-adjusted life year gained of around £6070 compared to no vasoactive drug. The analysis uses effectiveness evidence from a network meta-analysis. In contrast to previous guidelines recommending cilostazol, the analysis suggests that naftidrofuryl oxalate is the only vasoactive drug for PAD which is likely to be cost-effective.

The quality and impact of risk factor control in patients with stable claudication presenting for peripheral vascular interventions.

BACKGROUND: Peripheral arterial disease is a manifestation of systemic atherosclerosis and is predictive of future cardiovascular events. Clinical trial data have demonstrated that medical therapy can attenuate cardiovascular morbidity and mortality in patients with peripheral arterial disease. The utilization and impact of recommended medical therapy in a contemporary population of patients who undergo percutaneous interventions for lifestyle-limiting peripheral arterial disease is unknown. METHODS AND RESULTS: Using the Blue Cross Blue Shield of Michigan Cardiovascular Consortium Peripheral Vascular Intervention (BMC2 PVI) database, we identified 1357 peripheral vascular intervention encounters between January 2007 and December 2009 for the purpose of treating claudication. Before the intervention, 85% of these patients used aspirin, 76% used statin, 65% abstained from smoking, and 47% did all 3. There was no difference in cardiovascular events among those taking an aspirin and a statin on admission and those who were not. However, in both an unadjusted and a multivariable analysis, the odds of an adverse peripheral vascular outcome (repeat peripheral intervention, amputation, or limb salvage surgery) within 6 months decreased by more than half in patients receiving aspirin and statin therapy before peripheral vascular intervention as compared with those who received neither (odds ratio, 0.45; 95% CI, 0.29-0.71). CONCLUSIONS: The fundamental elements of medical therapy in patients with lifestyle-limiting claudication are often underutilized before referral for revascularization. Appropriate medical therapy before percutaneous revascularization is associated with fewer peripheral vascular events at 6 months.

Psychometric properties of the disease-specific health-related quality of life instrument VascuQoL in a Swedish setting.

BACKGROUND: Traditional outcome measures in peripheral arterial disease (PAD) provide insufficient information regarding patient benefit. It has therefore been suggested to add patient-reported outcome measures. The main aim of this study was to validate the Swedish Vascular Quality of Life questionnaire (VascuQoL) version, a patient-reported PAD-specific health-related quality of life (HRQoL) instrument. METHODS: Two-hundred PAD patients were consecutively recruited from two university hospitals. Out of the 200 subjects, 129 had intermittent claudication and 71 had critical limb ischemia. Mean age was 70 ± 9 y and 57% of the participants were male. All patients completed SF-36 and VascuQoL at the vascular outpatient clinic, when evaluated for invasive treatment. Risk factors and physiological parameters were registered. Construct validity was tested by correlation analysis versus SF-36 and was also assessed with multitrait/multi-item scaling analysis (MTMI). Sensitivity analysis regarding disease severity identification was performed. Reliability was assessed with Cronbach's alpha and responsiveness by standardized response mean (SRM) calculations. RESULTS: Significant correlations were demonstrated between relevant subscales of VascuQoL and SF-36. MTMI showed acceptable construct validity, but some scaling-errors. VascuQoL significantly (p < 0.001) discriminated claudicants from critical limb ischemia patients. Cronbach's alpha was 0.94 and SRM 1.02 (sum score). CONCLUSIONS: The Swedish version of VascuQoL is valid and quantifies central aspects of HRQoL in PAD patients. Sensitivity analysis showed high ability to differentiate between disease severity and SRM illustrated excellent responsiveness. The relative abundance of items however makes use in the everyday clinical setting somewhat difficult.

Near-infrared spectroscopy assessment following exercise training in patients with intermittent claudication and in untrained healthy participants.

Selected near-infrared spectroscopy (NIRS) parameters were assessed in healthy untrained participants and in peripheral arterial disease (PAD) trained patients to evaluate their usefulness in rehabilitative outcome. Forty-five PAD and 15 healthy participants were studied at entry and at 34 ± 2 weeks. Healthy participants performed their usual activities. Patients with PAD performed 2 home-based programs: structured at prescribed pace (S-pre, n = 31) and unstructured at free pace (U-free, n = 14). We measured ankle-brachial index (ABI), NIRS calf oxygen consumption at rest, NIRS dynamic muscle perfusion during an incremental test, and walking capacity. In all patients with PAD the NIRS parameters significantly increased approaching the stable values of untrained healthy participants. Among PAD, only S-pre group showed significant improvements in hemodynamic, functional, and NIRS parameters with selective adaptations in the worse legs. The assessment of NIRS parameters, that were found stable without training in healthy and modified in PAD only following structured training, might outline the local exercise-induced adaptations.

Occlusion of the internal iliac artery prior EVAR: comparison of coils and plugs.

PURPOSE: We compared occlusion of the internal iliac artery (IIA) using coils or the Amplatzer vascular plug (AVP) II prior to endovascular aortic aneurysm repair. MATERIALS AND METHODS: Occlusion of the IIA was performed in 32 patients (aged 74 ± 8 years) using coils (N = 17) or the AVP II (N = 15). We retrospectively compared procedural data, initial success, and clinical outcome in a 12-month follow-up. RESULTS: Occlusion was successful in all patients without detection of an endoleak after 12 months. Procedure time and fluoroscopy time for coils versus plugs were 77 ± 35 versus 43 ± 13 minutes and 36 ± 19 versus 18 ± 8 minutes, respectively (P < .003). Incidence of initial buttock claudication (BC) for coils versus plugs was 47% versus 27% and was significantly more severe after coil occlusion (P = .03). After a 12-month follow-up, 2 patients of each group reported of mild BC. CONCLUSION: Occlusion of the IIA is safe and effective using coils or plugs. Initial BC is significantly more severe when coils are used, but after a 12-month follow-up, there is no significant difference. Using a plug is associated with a significant reduction of procedure time and radiation exposure.

Influence of use of a vascular closure device on incidence and surgical management of access site complications after percutaneous interventions.

AIM: The study aimed to evaluate vascular access site complications (ASCs) after percutaneous interventions (PIs) in our institution for changes in annual incidence and surgical management after increased usage of a vascular closure device (VCD; in all cases: Angioseal™). MATERIAL AND METHODS: All patients who underwent repair of arterial pseudo-aneurysms or access site stenosis/occlusion leading to leg ischaemia (LI) or new-onset disabling claudication (CI) after PIs between 2001 and 2008 were included. Annual rates of procedures and methods of repair of ASC were evaluated. RESULTS: After a total of 58 453 PIs, 352 patients (0.6%) were operated on for: pseudo-aneurysms (n = 300; 0.51%); and local stenosis/occlusion leading to LI/CI (n = 52; 0.09%). Numbers increased significantly with more widespread VCD use: group A (2001-2004: 2860 VCDs; 28 284 PIs; 10.1%): n = 132 (0.47%); and group B (2005-2008: 11,660 VCDs; 30,169 PIs; 38.6%): n = 220 (0.73%) (p < 0.001). In contrast to similar rates of pseudo-aneurysms (group A: n = 124; 0.44%; group B: n = 176; 0.58%; not significant), a significant increase of operations for local stenoses/occlusions was seen with widespread VCD use: n = 8 versus n = 44 (p < 0.001). CONCLUSIONS: In the era of VCDs, complications are rare. However, use of these devices is not without complications, and may require complex reconstructions.

The effects of including quality of life responses in models to predict walking performance of patients with intermittent claudication.

OBJECTIVES: To examine the accuracy of previously developed prediction models of treadmill walking performance in patients with intermittent claudication (IC) due to peripheral arterial disease (PAD); and to examine the accuracy of new prediction models. DESIGN: Analysis of data collected in a previous randomised clinical trial. MATERIALS: Ninety-three assessments of 28 patients diagnosed with IC due to PAD. METHODS: Patients undertook routine clinical assessments, quality of life (QOL) questionnaires and treadmill walking tests. Walking performance and estimates based on prediction models were compared via paired t-tests or Wilcoxon Rank Sum tests. Stepwise linear regression generated models to predict walking performance from clinical measures and QOL responses. Accuracy was determined as the absolute error between model estimates and patient results. RESULTS: Walking performance was significantly underestimated (35-71% error) by previously developed prediction models. Models developed in the current study identified QOL responses as the most significant predictors of current walking performance but these models still resulted in substantial errors (19-84%). CONCLUSIONS: Previously published predictors of walking performance significantly underestimated patient's ability in practise. Predictions based upon clinical measurements and QOL responses were developed however, their accuracy was also limited. Further research is needed regarding walking performance prediction to assist clinicians with assessment of PAD severity and treatment effectiveness.

The Felix-trial. Double-blind randomization of interspinous implant or bony decompression for treatment of spinal stenosis related intermittent neurogenic claudication.

BACKGROUND: Decompressive laminotomy is the standard surgical procedure in the treatment of patients with canal stenosis related intermittent neurogenic claudication. New techniques, such as interspinous process implants, claim a shorter hospital stay, less post-operative pain and equal long-term functional outcome. A comparative (cost-) effectiveness study has not been performed yet. This protocol describes the design of a randomized controlled trial (RCT) on (cost-) effectiveness of the use of interspinous process implants versus conventional decompression surgery in patients with lumbar spinal stenosis. METHODS/DESIGN: Patients (age 40-85) presenting with intermittent neurogenic claudication due to lumbar spinal stenosis lasting more than 3 months refractory to conservative treatment, are included. Randomization into interspinous implant surgery versus bony decompression surgery will take place in the operating room after induction of anesthesia. The primary outcome measure is the functional assessment of the patient measured by the Zurich Claudication Questionnaire (ZCQ), at 8 weeks and 1 year after surgery. Other outcome parameters include perceived recovery, leg and back pain, incidence of re-operations, complications, quality of life, medical consumption, absenteeism and costs. The study is a randomized multi-institutional trial, in which two surgical techniques are compared in a parallel group design. Patients and research nurses are kept blinded of the allocated treatment during the follow-up period of 1 year. DISCUSSION: Currently decompressive laminotomy is the golden standard in the surgical treatment of lumbar spinal stenosis. Whether surgery with interspinous implants is a reasonable alternative can be determined by this trial. TRIAL REGISTER: Dutch Trial register number: NTR1307.

Resting energy expenditure in patients with intermittent claudication and critical limb ischemia.

OBJECTIVE: The primary aim of this study was to compare the resting energy expenditure of patients with intermittent claudication and critical limb ischemia. A secondary aim was to identify predictors of resting energy expenditure. METHODS: One hundred patients limited by intermittent claudication and 40 patients with critical limb ischemia participated in this study. Patients were assessed on resting energy expenditure, body composition, ankle brachial index (ABI), and calf blood flow. RESULTS: Patients with critical limb ischemia had a lower resting energy expenditure than patients with intermittent claudication (1429 +/- 190 kcal/day vs 1563 +/- 229 kcal/day; P = .004), and higher body fat percentage (34.8 +/- 7.8% vs 31.5 +/- 7.8%; P = .037), higher fat mass (30.0 +/- 9.3 kg vs 26.2 +/- 8.9 kg;P = .016), and lower ABI (0.31 +/- 0.11 vs 0.79 +/- 0.23; P < .001). Resting energy expenditure was predicted by fat free mass (P < .0001), age (P < .0001), ABI (P < .0001), ethnicity (P < .0001), calf blood flow (P = .005), and diabetes (P = .008). Resting energy expenditure remained lower in the patients with critical limb ischemia after adjusting for clinical characteristics plus fat free mass (1473 +/- 27.8 kcal/day [mean +/- SEM] vs 1527 +/- 19.3 kcal/day; P = .031), but it was no longer different between groups after further adjustment for ABI and calf blood flow (1494 +/- 25.2 kcal/day vs 1505 +/- 17.7 kcal/day; P = .269). CONCLUSION: Resting energy expenditure is decreased with a progression in peripheral arterial disease (PAD) symptoms from intermittent claudication to critical limb ischemia. Furthermore, patients with critical limb ischemia who are most susceptible for decline in resting energy expenditure are older, African American patients with diabetes. The lower resting energy expenditure of patients with critical limb ischemia, combined with their sedentary lifestyle, suggests that they are at high risk for long-term positive energy balance and weight gain.

Walking economy before and after the onset of claudication pain in patients with peripheral arterial disease.

PURPOSE: To determine the walking economy before and after the onset of claudication pain in patients with peripheral arterial disease (PAD), and to identify predictors of the change in walking economy following the onset of claudication pain. METHODS: A total of 39 patients with PAD were studied, in which 29 experienced claudication (Pain group) during a constant load, walking economy treadmill test (speed = 2.0 mph, grade = 0%) and 10 were pain-free during this test (Pain-Free group). Patients were characterized on walking economy (ie, oxygen uptake during ambulation), as well as on demographic characteristics, cardiovascular risk factors, baseline exercise performance measures, and the ischemic window calculated from the decrease in ankle systolic blood pressure following exercise. RESULTS: During the constant load treadmill test, the Pain group experienced onset of claudication pain at 323 +/- 195 seconds (mean +/- standard deviation) and continued to walk until maximal pain was attained at 759 +/- 332 seconds. Walking economy during pain-free ambulation (9.54 +/- 1.42 ml x kg(-1) x min(-1)) changed (P < .001) after the onset of pain (10.18 +/- 1.56 ml x kg(-1) x min(-1)). The change in walking economy after the onset of pain was associated with ischemic window (P < .001), hypertension (P < .001), diabetes (P = .002), and height (P = .003). In contrast, the Pain-Free group walked pain-free for the entire 20-minute test duration without a change in walking economy (P = .36) from the second minute of exercise (9.20 +/- 1.62 ml x kg(-1) x min(-1)) to the nineteenth minute of exercise (9.07 +/- 1.54 ml x kg(-1) x min(-1)). CONCLUSION: Painful ambulation at a constant speed is associated with impaired walking economy, as measured by an increase in oxygen uptake in patients limited by intermittent claudication, and the change in walking economy is explained, in part, by severity of PAD, diabetes, and hypertension.