Six-minute walk distance target in elderly patients with idiopathic pulmonary arterial hypertension - consideration of predicted values.
BACKGROUND
The number of elderly patients diagnosed with idiopathic pulmonary arterial hypertension (IPAH) is increasing. A 6-min walk distance (6MWD) > 380 m on therapy is associated with improved survival in IPAH. As exercise capacity is naturally decreasing with age, treatment goals for elderly patients might be different from those established for younger patients.


METHODS
Consecutive adult patients diagnosed with IPAH between 1/2005 and 7/2012 were retrospectively included. We analysed the prognostic value of 6MWD targets (in metres and % predicted) with respect to age at diagnosis.


RESULTS
The mean (± SD) 6MWD in 23 patients aged > 65 years at diagnosis compared with 22 younger patients was significantly lower at baseline (262 ± 69 vs. 356 ± 128 m; p = 0.011) and first follow up (310 ± 75 vs. 377 ± 137 m; p = 0.045), while the corresponding % predicted values were similar (62 ± 16% vs. 63 ± 21%; p = 0.854, and 74 ± 16% vs. 68 ± 21%; p = 0.267). The established treatment target of > 380 m 6MWD was met by only 13% of elderly compared with 46% of younger patients (p = 0.016), while the corresponding 6MWD of 78% predicted was exceeded by similar proportions (48% and 46%, respectively; p = 0.873). Survival of patients walking > 380 m or 78% predicted on first follow up was significantly better compared with patients not exceeding the respective threshold (100% vs. 72% and 95% vs. 67% at the end of follow up, respectively; p < 0.05 each).


CONCLUSIONS
Expression of the 6MWD target as % predicted equalises age-related differences and has similar prognostic power compared with absolute values in patients with IPAH. As elderly patients are less likely to reach the absolute 6MWD threshold, the use of % predicted could be helpful in their individual assessment and adaption of targeted therapy.
Department of Internal Medicine II, Division of Pneumology, University Medical Center Regensburg, Regensburg, Germany.
T J
TJ
Lange
A
A
Keller
M
M
Arzt
M
M
Pfeifer
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005080:Exercise Test / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016138:Walking / Q000502:physiology*