title: Patient Activity and Survival Following Implantable Cardioverter-Defibrillator Implantation: The ALTITUDE Activity Study.
abstract: BACKGROUND
  Physical activity data are collected automatically by implantable cardioverter-defibrillators (ICDs). Though these data potentially provide a quantifiable and easily accessible measure of functional status, its relationship with survival has not been well studied.
  
  
  RESULTS
  Patients enrolled in the Boston Scientific LATITUDE remote monitoring system from 2008 to 2012 with ICDs were eligible. Remote monitoring data were used to calculate mean daily activity at baseline (30 to 60 days after implantation), and longitudinally. Cox regression was used to examine the association between survival and increments of 30 minutes/day in both (1) mean baseline activity and (2) time-varying activity, with both adjusted for demographic and device characteristics. A total of 98 437 patients were followed for a median of 2.2 years (mean age of 67.7±13.1 years; 71.7% male). Mean baseline daily activity was 107.5±66.2 minutes/day. The proportion of patients surviving after 4 years was significantly higher among those in the most versus least active quintile of mean baseline activity (90.5% vs. 50.0%; log-rank P value, <0.001). Lower mean baseline activity (i.e., incremental difference of 30-minutes/day) was independently associated with a higher risk of death (adjusted hazard ratio [AHR], 1.44; 95% confidence interval [CI], 1.427 to 1.462). Time-varying activity was similarly associated with a higher risk of death (AHR, 1.48; 95% CI, 1.451 to 1.508), indicating that a patient having 30 minutes per day less activity in a given month has a 48% increased hazard for death when compared to a similar patient in the same month.
  
  
  CONCLUSIONS
  Patient activity measured by ICDs strongly correlates with survival following ICD implantation.
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA (D.B.K., S.L.M.) Harvard Medical School, Boston, MA (D.B.K., S.L.M., S.L.N.) Hebrew SeniorLife Institute for Aging Research, Boston, MA (D.B.K., S.L.M.).
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Kramer
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA (D.B.K., S.L.M.) Harvard Medical School, Boston, MA (D.B.K., S.L.M., S.L.N.) Hebrew SeniorLife Institute for Aging Research, Boston, MA (D.B.K., S.L.M.).
authors.forename: Susan L
authors.initials: SL
authors.lastname: Mitchell
authors.affiliation: North American Science Associates, Inc, Minneapolis, MN (J.M.).
authors.forename: Joao
authors.initials: J
authors.lastname: Monteiro
authors.affiliation: Boston Scientific, St Paul, MN (P.W.J.).
authors.forename: Paul W
authors.initials: PW
authors.lastname: Jones
authors.affiliation: Harvard Medical School, Boston, MA (D.B.K., S.L.M., S.L.N.) Harvard School of Public Health, Boston, MA (S.L.N.).
authors.forename: Sharon-Lise
authors.initials: SL
authors.lastname: Normand
authors.affiliation: Mayo Clinic, Rochester, MN (D.L.H.).
authors.forename: David L
authors.initials: DL
authors.lastname: Hayes
authors.affiliation: Lahey Clinic, Burlington, MA (M.R.R.) Harvard Clinical Research Institute, Boston, MA (M.R.R.).
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Reynolds
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D001900:Boston; D017147:Defibrillators, Implantable / Q000009:adverse effects* / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
keywords: death; implantable cardioverter‐defibrillators; sudden