Anchor-based estimates of minimal clinically important difference (MCID) for worsening in idiopathic pulmonary fibrosis from current study and comparison with MCID estimates from previous studies
| Current MCID estimate | Previous MCID estimate# | |||
| Time period¶ | MCID+ (95% CI) | Time period [ref.] | MCID | |
| 6MWD m | 24 weeks | −74.89 (−93.11– −56.66) | 48 weeks [14] | 24–45§ |
| 48 weeks [16] | 21.7 –37.0§ | |||
| 52 weeks [11] | 28 | |||
| SF-36 physical component score | 60 weeks | −6.79 (−8.66– −4.92) | 26 weeks [13] | 3 |
| No specified time period [10] | 5 | |||
| Total SGRQ score | 60 weeks | 10.95 (7.81–14.1) | 26 weeks [13] | 7 (5–10)## |
| 52 weeks [12] | 4–5 | |||
| UCSD SOBQ total score | 60 weeks | 11.38 (7.83–14.93) | 24 weeks [19] | 8 (5–11)## |
6MWD: 6-min walk distance; SF-36: 36-Item Short-Form Health Survey; SGRQ: St George's Respiratory Questionnaire; UCSD SOBQ: University of California, San Diego Shortness of Breath Questionnaire. #: previous studies have estimated MCID values for worsening and improvement using both anchor-based and distribution-based methods; ¶: 6MWD met responsiveness criteria only in the Sildenafil Trial of Exercise Performance in Idiopathic Pulmonary Fibrosis (STEP-IPF) cohort, while the SF-36 physical component score, SGRQ and UCSD SOBQ met criteria in only the Prednisone, Azathioprine, and N-Acetylcysteine: A Study That Evaluates Response in Idiopathic Pulmonary Fibrosis (PANTHER-IPF) cohort; therefore, time period for MCID is 24 weeks or 60 weeks; +: MCID for worsening only, since it was calculated as mean change in “somewhat worse” health transition question (SF2) group from baseline to follow-up; §: range; ##: point estimate (range).