There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .
Short- and long-term effects of outpatient rehabilitation in patients with chronic obstructive pulmonary disease: a randomized trial.
PURPOSE Pulmonary rehabilitation programs are effective in patients with severe chronic obstructive pulmonary disease ( COPD ) in the short term , but their long-term effects are not known . We investigated the short- and long-term effects of a 6-month outpatient rehabilitation program in patients with severe COPD . SUBJECTS AND METHODS One hundred patients were r and omly assigned to receive either an exercise training program that included cycling , walking , and strength training ( n = 50 ) or usual medical care ( n = 50 ) . Thirty-four patients in the training group were evaluated after 6 months ( end of training ) , and 26 were evaluated after 18 months of follow-up . In the control group , 28 patients were evaluated at 6 months and 23 after 18 months . We measured pulmonary function , 6-minute walking distance , maximal exercise capacity , peripheral and respiratory muscle strength , and quality of life ( on a 20 to 140-point scale ) , and estimated the cost-effectiveness of the program . RESULTS At 6 months , the training group showed improvement in 6-minute walking distance [ mean difference ( training - control ) of 52 m ; 95 % confidence interval ( CI ) , 15 to 89 m ] , maximal work load ( 12 W ; 95 % CI , 6 to 19 W ) , maximal oxygen uptake ( 0.26 liters/min ; 95 % CI , 0.07 to 0.45 liters/min ) , quadriceps force ( 18 Nm ; 95 % CI , 7 to 29 Nm ) , inspiratory muscle force ( 11 cm H(2)O ; 95 % CI , 3 to 20 cm H(2)O ) , and quality of life ( 14 points ; 95 % CI , 6 to 21 points ; all P < 0.05 ) . At 18 months all these differences persisted ( P < 0.05 ) , except for inspiratory muscle strength . For 6-minute walking distance and quality of life , the differences between the training group and controls at 18 months exceeded the minimal clinical ly-important difference . CONCLUSION Among patients who completed the 6-month program , outpatient training result ed in significant and clinical ly relevant changes in 6-minute walking distance , maximal exercise performance , peripheral and respiratory muscle strength , and quality of life . Most of these effects persisted 18 months after starting the program
There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .