Understanding the Pain Trajectory During Treadmill Testing in Peripheral Artery Disease

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1 Understanding the Pain Trajectory During Treadmill Testing in Peripheral Artery Disease Diane Treat-Jacobson, PhD, RN, FAHA, FAAN Susan J. Henly, PhD, RN Ulf G. Bronas, PhD, ATC, ATR Arthur S. Leon, MD, MS U of M School of Kinesiology George A. Henly, PhD Minnesota Department of Education

Henly, PhD, RN Ulf G. Bronas, PhD, ATC, ATR Arthur S.

2 Background and Significance Peripheral arterial disease (PAD) is a progressive atherosclerotic disease Affects approximately 9 million Americans Symptoms of PAD are related to insufficient arterial blood flow, which results in debilitating, activity-induced, ischemic pain (claudication) Associated with major limitations in mobility and physical functioning, and decreased quality of life.

arterial blood flow, which results in debilitating, activity-induced, ischemic pain

3 Background and Significance Efficacy of treadmill training to improve walking distance in patients with claudication is well established. Mechanisms by which exercise training improves walking include both local and systemic changes.

4 What are the mechanisms of improvement in walking distance? Local conditioning effect changes in muscle metabolism stimulated by exercising specific muscles affected by limited blood flow Systemic effect changes in central cardiovascular conditioning and/or vascular function, leading to improved walking ability Our research challenges the current prevalent paradigm is that inducing skeletal muscle ischemia during exercise is necessary to obtain benefit

limited blood flow Systemic effect changes in central cardiovascular conditioning and/or vascular function,

5 What about upper body exercise? Aerobic upper body exercise (arm ergometry) as an exercise alternative: Pain-free and therefore may be better-tolerated Has potential systemic benefits for the lower extremity arterial system. Doesn t create ischemia during exercise Exercise intensity is not limited by symptoms, but by level of cardiovascular conditioning

therefore may be better-tolerated Has potential systemic benefits for the lower

6 Conceptual Framework Pathophysiological Changes that Occur with PAD Physiological Outcomes with Aerobic Training Arterial Flow Cardiac Output Endothelial Dysfunction Inflammation Deconditioning Health and Functional Consequences Treadmill Walking (Ischemic)? Cardiovascular Conditioning Cardiac output Leg blood flow/? Arm blood flow Endothelial Dysfunction Inflammation Arm Ergometry (Non-Ischemic) Cardiovascular Conditioning Cardiac output Arm blood flow/? Leg blood flow Endothelial Dysfunction Inflammation Walking Ability Functional Status Quality of Life Mood Health and Functional Outcomes Walking Ability Functional Status Quality of Life Mood

Cardiovascular Conditioning Cardiac output Leg blood flow/?

7 Pain: Definition & Dimensions An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage Intensity; quality; time course; functional and emotional impact; and personal meaning are very subjective IASP;

quality; time course; functional and emotional impact; and personal meaning are very

8 Pain Trajectory An individual s experienced pain intensity over time The dynamic course of pain A longitudinal characterization of the pain experience as a growth curve Translation of each dynamic course of pain to a testable statistical model

characterization of the pain experience as a growth curve

9 Claudication Pain in Peripheral Artery Disease Decreased blood flow to legs results in skeletal muscle ischemia With walking, the ischemia produces pain distal to arterial stenosis Cramp-like pain commences after exercise begins, may become severe within seconds or minutes, reaches a maximum that limits movement, resolves with cessation of exercise, but recurs whenever exercise is resumed

pain commences after exercise begins, may become severe within seconds or minutes, reaches a

10 Exercise Training for Claudication (ETC) Study Subjects with lifestyle limiting claudication pain Randomized Treadmill Walking n= Combination n= Arm Ergometry n= Control n=8 Pain free walking distance (PFWD) at Weeks Maximal walking distance (MWD) at weeks

Walking n= Combination n= Arm Ergometry n= Control n=8 Pain

11 Study Procedures - weeks Screening Visit Screening Visit Screening Visit Exercise Training week Follow up week Follow up Weeks Weeks Informed Consent, Medical History ABI Graded treadmill test # Graded treadmill test # sessions/wk Supervised Exercise Graded treadmill test Graded treadmill test Randomization

Consent, Medical History ABI Graded treadmill test # Graded treadmill test #

12 Outcome Measurement Graded, symptom-limited treadmill test Start at mph, % grade Increase.% every minutes up to.% grade Then increase speed by. mph every minutes Claudication pain severity assessed every seconds using claudication scale: (no pain) to (maximal pain)

13 Claudication Scale Severe Pain (can go no longer) Moderate Pain Onset of Pain (mild) No Pain

14 Exercise Interventions for Claudication Pain Treat-Jacobson et al. (9). Efficacy of arm-ergometry versus treadmill exercise training to improve walking distance in patients with claudication. Vascular Medicine,, -. Purpose: Compare efficacy of exercise interventions Design: RCT N = Treatments: Supervised TM, AE, TM + AE, UC; weeks Assessment: Pain during treadmill testing Measurement: Pain ( to ) every seconds Outcomes: log (PFWD), log (MWD) at, weeks adjusted for baseline Results: TM, AE, TM+AE better than UC Conclusion: AE is feasible and produces results different from TM or TM+AE over time

Purpose: Compare efficacy of exercise interventions Design: RCT N = Treatments: Supervised TM, AE, TM + AE, UC; weeks Assessment: Pain during

15 Group versus individual response to an intervention Describing the average response of the group gives information about overall status Important when determining the best strategies for a population However Limiting analysis to descriptions of the group as a whole may miss different patterns of change Understanding of individual patterns of response may facilitate individualized interventions

population However Limiting analysis to descriptions of the group as a whole may miss different

16 Secondary Analysis: Pain Trajectories as Outcomes at Weeks Functional limitations (PFWD, MWD) arise from pain Every claudication episode is experienced as a pain trajectory Plan: Use pain trajectories as outcomes to understand individual experiences of claudication and experimental effects of different modes of exercise training Treat-Jacobson et al. (). The pain trajectory in peripheral arterial disease. Nursing Research, 6 (Supp.). (In press)

understand individual experiences of claudication and experimental effects of different modes of exercise

17 Graphing Observed Pain Trajectories during Treadmill Testing Baseline Severe Pain Weeks Severe Pain Pain Self-Report Moderate Pain Onset of Pain Pain Self-Report Moderate Pain Onset of Pain No Pain No Pain Time (Seconds) Time (Seconds)

Moderate Pain Onset of Pain Pain Self-Report Moderate Pain

18 Seeing Treatment Effects in Observed Trajectories Highest pain levels Every step Onset & lower pain levels Onset only No apparent difference Pain Pain Pain Pain Pain Baseline ID # Seconds ID # Seconds ID # Seconds ID # Seconds ID # Seconds Pain Pain Pain Pain Pain Weeks ID # Seconds ID # Seconds ID # Seconds ID # Seconds ID # Seconds

78 6 Seconds ID # 7 6 78 6 Seconds ID # 6 78 6 Seconds ID # 6 78 6 Seconds Pain Pain Pain Pain Pain

19 Hypotheses and Model Individual pain trajectories vary at baseline Treatment affects pain trajectories at weeks Treatment-by-time interaction affects pain trajectories at weeks Hierarchical generalized linear model for ordinal outcomes over time using a logit link function HLM

interaction affects pain trajectories at weeks Hierarchical

20 Pain Scores and Claudication Assume the thresholds are the same for all people Claudication is monotonically increasing up to the maximum, over time, so that Low scores are used less often as time goes by High scores are used more frequently as time goes by During walking, the probability of responding with scores of,,,,, or changes over time

scores are used less often as time goes by High scores are used more frequently as

21 Overall Average Effects Expected Mean Response by Group.. Rating. BL TM CB AE UC Seconds

22 Individual Effects: Usual Care 6 Subject Baseline Observed Pain Baseline Modeled Treatment Observed Treatment Modeled 6 7 Seconds

23 Individual Effects: Arm Ergometry 6 Subject Pain Baseline Observed Baseline Modeled Treatment Observed Treatment Modeled Seconds

24 Individual Effects: Treadmill Subject Pain Baseline Observed Baseline Modeled Treatment Observed Treatment Modeled 6 8 Seconds

25 Individual Effects: Combination 6 Subject 6 Pain Baseline Observed Baseline Modeled Treatment Observed Treatment Modeled Seconds

26 Personal Claudication Visual image of experienced pain trajectory Shows gripping progressive intensity Claudication as dynamic phenomenon, unfolding in time Complements classic functional outcomes

27 Using Individual Level Information Debrief clinic patients about their pain experiences Point out how pain might be mitigated across the claudication trajectory Tailor exercise interventions to maximize effectiveness for individuals

28 Treatment Effects on Trajectories UC: has some effect TM: effect at high levels of pain AE: effect at lower levels of pain CB: both, but muted Outcomes may reflect mechanisms: AE: systemic conditioning? TM: local muscle adaptation? Change in pain tolerance?

29 Future Research Power: within tests, consideration of duration, timing, frequency of observations, plus sample size Increased frequency of treadmill tests in exercise trials Combining real-time monitoring of skeletal muscle ischemia and trajectory modeling

30 Acknowledgements American Heart Association Scientist Development Grant #Z University of Minnesota Academic Health Center Clinical Scholar Program Co-investigators and Co-Authors Sue Henly, PhD, RN Ulf Bronas, PhD Arthur S Leon, MD George Henly, PhD

Efficacy of arm-ergometry versus treadmill exercise training to improve walking distance in patients with claudication

Efficacy of arm-ergometry versus treadmill exercise training to improve walking distance in patients with claudication Diane Treat-Jacobson University of Minnesota School of Nursing; Center for Gerontological