ORIGINAL ARTICLE Activity Levels Among Lower-Limb Amputees: Self-Report Versus Step Activity Monitor Jacqueline M. Stepien, BSc, Sally Cavenett, BPO, Leigh Taylor, MPH, Maria Crotty, PhD ABSTRACT. Stepien JM, Cavenett S, Taylor L, Crotty M. Activity levels among lower-limb amputees: self-report versus step activity monitor. Arch Phys Med Rehabil 2007;88: 896-900. Objective: To determine the accuracy of self-reported ac- tivity by community-dwelling, lower-limb amputees. Design: Descriptive study. Setting: A regional prosthetics outpatient service. Participants: Seventy-seven unilateral lower-limb amputees at least 6 months after prosthetic rehabilitation. Interventions: Not applicable. Main Outcome Measures: Measured activity counts (in steps/min) and self-reported activity (rest, low, medium, high) in 15-minute intervals over 1 week were recorded for each participant. Results: Participants averaged 30631893 steps per day. Strong agreement (0.7) between self-reported and measured activity was found for only 34% of participants between the hours of 9:00 AM to 9:00 PM. The measured and self-reported proportion of time spent in various states of activity also showed poor agreement (rest, r=.41; low level activity, r=.39; medium level, r=.26; high level, r=.40). There was no bias toward either over- or under-reporting. Conclusions: The majority of participants were unable to accurately self-report their activity levels (sleep excluded) as compared with measured activity levels. This may have impor- tant implications for prescribing appropriate prosthetics and for clinicians who provide patients with advice on promoting health. Key Words: Amputees; Physical effort; Rehabilitation; Validation studies. © 2007 by the American Congress of Rehabilitation Medi- cine and the American Academy of Physical Medicine and Rehabilitation P ROMOTING ACTIVITY AND FITNESS is an important component of clinical encounters with amputees inasmuch as they often have significant comorbidities and face challenges in conventional exercise approaches. Inappropriate prescription of a prosthesis significantly affects an amputee’s comfort and mobility, 1 and also has financial implications for funding agen- cies. Current practice is to use scales such as Medicare k-levels and Otto Bock Mobis, 2 both of which take into consideration daily ambulatory activity levels and a patient’s weight to guide the prescription of an appropriate prosthesis. Clinically, activ- ity levels are commonly determined from patients’ self-reports and evidence on the reliability of these reports in community- dwelling amputees is lacking. The prescription of inappropriate prostheses may have an impact on activity and therefore make it difficult for clinicians to compel amputees to participate in interventions that promote increased activity. Previous research involving other adult populations has shown that validating measured ambulatory activity against self-reported ambulatory activity leads to conflicting results, including strong positive correlations, 3,4 poor-to-moderate pos- itive correlations, 5-7 or overestimation of activity frequency and intensity. 8,9 Recall limitations are also associated with self-report measures. Measured ambulatory function in these studies has been quantified by several instruments, including pedometers, 3,4 accelerometers, 5,8 and heart rate monitors. 9 To determine daily activity in the amputee population, and particularly concerning prosthetic use, a device that can be attached to the prosthesis should yield high quality data. A step activity monitor (SAM) can be attached to a prosthetic limb to record the activity of that limb only; it is a combination of an accelerometer and step counter and is therefore better able than pedometers to detect movement by people with different gait patterns. 10 The StepWatch3 a Activity Monitor has been shown to accurately record the number of steps taken in normal walking and in climbing or descending stairs. 10 StepWatch3 has also been shown to produce significantly less absolute errors in steps taken than do pedometers 11 and can record steps per minute, therefore determining intensity of activity at any given time. Previous studies 10 have shown that StepWatch3 has an overall accuracy of 99.7% when used in the lower-limb amputee population. As a self-report measure, an activity diary is most likely the best method with which to compare self- reported levels of activity to SAM. Therefore, our goals in this study were to quantify the number of steps lower-limb amputees take per day, and to determine whether they accurately self-reported their daily activity levels using an activity diary when those levels were compared with their levels as measured by the SAM. METHODS Participants Participants were recruited from a regional prosthetic service between May and October 2005 through a letter of invitation sent to eligible participants. Telephone calls were then made to confirm that they received the letter, that they still fulfilled the study criteria, and that they wanted to participate. Eligible participants were identified from a patient register, using the following criteria: unilateral lower-limb amputation; residing in unsupported care and using their prosthesis for primary ambulation (with or without the use of gait aids), a minimum of 6 months post-prosthetic rehabilitation, older than 18 years, and cognitively capable of completing questionnaires and maintaining a self-report diary of activity. From the Department of Rehabilitation and Aged Care, Flinders University, Daw Park, SA, Australia. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Correspondence to Maria Crotty, PhD, Flinders University Department of Reha- bilitation and Aged Care, Repatriation General Hospital, Daws Rd, Daw Park, SA 5041, Australia, e-mail: Maria.Crotty@flinders.edu.au. Reprints are not available from the author. 0003-9993/07/8807-11298$32.00/0 doi:10.1016/j.apmr.2007.03.016 896 Arch Phys Med Rehabil Vol 88, July 2007