From: Evaluation of the measurement properties of the Manchester foot pain and disability index
Measurement property | Research question | Method | Dataset(s) | Results | Interpretation |
---|---|---|---|---|---|
Responsiveness | Do change scores on the MFPDI relate to change scores on other instruments as expected? | Pearsson Correlation* | Comparator instruments: FFI, NRS, SF12phys, GPEpain and GPEfunction | The responsiveness of the MFPDI is moderate; only 1 out of 7 hypotheses was confirmed and the correlation with the GPE question is < 0.2. | |
Testing 7 a priori defined hypotheses: | |||||
1. Correlation change MFPDI-f and FFI-f (R > 0.5) | T0 and measurement after 3 months (NL T3) | 1. R 0.31 (p < 0.000) | |||
2. Correlation change MFPDI-f and SF12 phys (R > 0.5) | n = 178 | 2. R 0.03 (p = 0.747) | |||
3. Correlation change MFPDI-f and GPE-f (R > 0.5) | 3. R -0.46 (p < 0.000) | ||||
4. R hypothesis 1 > R hypothesis 2. | 4. R 0.31 > R 0.03* | ||||
5. Correlation change MFPDI-p and FFI-p (R > 0.5) | 5. R 0.37 (p < 0.000) | ||||
6. Correlation change MFPDI-p and pain NRS (R > 0.5) | 6. R 0.42 (p < 0.000) | ||||
7. Correlation change MFPDI-p and GPE-p (R > 0.5) | 7. R -0.47 (p < 0.000) | ||||
*A priori defined hypothesis | |||||
Interpretability | What is the Minimal Important change (MIC)? | MIC: smallest cut-off change score (1-sensitivity)+ | MIC: NL T0, | The correlation coefficient between the GPE and change score is too low to calculate a MIC (R < 0.5). | The MFPDI is not responsive enough to calculate a MIC. |
NL T3 | |||||
(1-specificity) | n = 178 | ||||
What is the Smallest Detectable Change (SDC)? And is the MIC higher than the SDC? | SDC | SDC: NL T0 n = 205 | SDC: | The SDC for the perception sub-scale is too large; the SDC is equal to the maximum possible score. | |
Function: 6.1 (min-max score: 0–18) | |||||
Pain: 4.4 (0–10) | |||||
Perception: 5.8 (0–6) | |||||
Is a floor and or ceiling effect present? | Floor/ceiling effect: % of participants who scored the two lowest possible scores (0 or1) per sub-scale. | Floor/ceiling effect: NL T0 n = 205 | Floor/ceiling effects: | The perception sub-scale exhibits a large floor effect. | |
Function: 8.8% | |||||
Pain: 7.4% | |||||
Perception: 76.5% |