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Pedometer Testing Predicts Kidney Transplant Evaluation Outcome
*Priyadarshini Manay1, *Patrick Ten Eyck1, *Grace Binns2, Daniel A Katz1
1University of Iowa Hospitals and Clinics, Iowa City, IA;2Iowa City Veterans Affairs Hospital, Iowa City, IA

OBJECTIVE(S): Treadmill ability and other functional metrics are predictive of transplant outcomes. We hypothesized that pedometer and treadmill results would correlate and that pedometer data could also predict listing outcomes.
METHODS: Frailty metrics, treadmill ability (METS), pedometer data and troponin were collected on 373 consecutive patients evaluated for transplant between July 2015 and December 2018 and correlated with listing outcomes. Patients initially denied were compared to those listed or deferred. Frailty metrics included handgrip, chair sit/stand, 8 foot up-and-go, sit/reach and questions related to fatigue. Data from calibrated accelerometers were collected over the 1-3-day evaluation period and reported as steps and calculated distance per time. The listing committee was blinded to pedometer and frailty data.
RESULTS: 278 (75%) patients were initially listed or deferred, and 95 (25%) denied. Demographic and functional metric correlations with listing are presented in the tables. Denied patients tended to be older, diabetic, and with higher BMIs. Race and length of time on dialysis were not associated with listing outcome. On multivariable analysis, functional parameters that most correlated with listing included treadmill ability, pedometer data, fatigue questions, and 8 foot up-and-go. The best models incorporating pedometer data that combined parsimony with predictiveness included self reported fatigue and 8 foot up-and-go. Walking less than either 500 steps per day or less than .25 miles per day, combined with both "couldn't get going" 2 or more days per week and up-and-go ≥ 10 seconds, predicted transplant denial 84% and 92% of the time, respectively and was as predictive as models utilizing treadmill data. Spearman analysis showed correlation between treadmill and pedometer ability (r=.50, p<.0001).
CONCLUSIONS: Pedometer activity was predictive of listing outcomes and correlated with treadmill ability. Activity tracking could be a cost-effective method for screening kidney transplant candidates.

DemographicInitially Listed or Deferred mean (sd)Initially Denied mean (sd)p
Age60.1 (9.6)62.6 (9.8)0.0311
BMI29.5 (4.4)31.2 (5.0)0.0019
Race: White57.8%56.8%0.9397
Time on Dialysis (days)797.5 (894.7)948.8 (1072.8)0.3596

Measured Factors
Measured FactorsInitially Listed or Deferred mean (sd)Initally Denied mean (sd)p
Troponin0.06 (0.08)0.09 (0.10)0.0002
Treadmill (METS)5.8 (2.2)3.5 (1.7)<0.0001
Pedometer(steps/day)8432 (5662)5741 (4228)<0.0001
Pedometer(distance/day, miles)3.3 (2.4)2.1 (1.7)<0.0001
Max hand grip (kg)34.0 (9.6)29.6 (7.6)0.0002
8 ft up-and-go5.6 (1.8)7.6 (3.9)<0.0001
Chair sit/stand (reps/30sec)14.9 (6.0)11.5 (5.1)<0.0001
Sit/reach (cm)4.6 (7.9)7.6 (9.8)0.0008
How many days in past week couldn't you get going?0.69 (1.52)1.73 (2.45)<0.0001

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