The ‘smallest real difference’ as a measure of sensitivity to change: a critical analysis

Schuck, Peter; Zwingmann, Christian

doi:10.1097/01.mrr.0000070759.63544.65

Cited by 30 publications

(28 citation statements)

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“…The objective of this study was not to determine MCID. However, the MCID for neurological recovery has been repeatedly suggested as being at least equal to the smallest real difference (SRD) 21-23 :…”

Section: Discussionmentioning

confidence: 99%

Relationship Between Motor Recovery and Independence After Sensorimotor-Complete Cervical Spinal Cord Injury

Kramer

Lammertse

Schubert

et al. 2012

Neurorehabil Neural Repair

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BACKGROUND: For therapeutics directed to the injured spinal cord, a change in neurological impairment has been proposed as a relevant acute clinical study end point. However, changes in neurological function, even if statistically significant, may not be associated with a functional impact, such as a meaningful improvement in items within the self-care subscore of the Spinal Cord Independence Measure (SCIM). OBJECTIVE: The authors examined the functional significance associated with spontaneously recovering upper-extremity motor function after sensorimotor-complete cervical spinal cord injury (SCI). METHODS: Using the European Multi-center Study about Spinal Cord Injury (EMSCI) data set, a retrospective analysis was undertaken of individuals with cervical sensorimotor-complete SCI (initial motor level, C4-C7). Specifically, changes in upper-extremity motor score (UEMS), motor level, and SCIM (total and self-care subscore) were assessed between approximately 1 and 48 weeks after injury (n = 74). RESULTS: The initial motor level did not significantly influence the total UEMS recovered or number of motor levels recovered. SCIM self-care subscore recovery was significantly greater for those individuals regaining 2 motor levels compared with those recovering only 1 or no motor levels. However, the recovery in the SCIM self-care subscore was not significantly different between individuals recovering only 1 motor level and those individuals who showed no motor-level improvement. CONCLUSIONS: A 2 motor-level improvement indicates a clinically meaningful change and might be considered a primary outcome in acute and subacute interventional trials enrolling individuals with cervical sensorimotor-complete SCI.

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Section: Discussionmentioning

confidence: 99%

Relationship Between Motor Recovery and Independence After Sensorimotor-Complete Cervical Spinal Cord Injury

Kramer

Lammertse

Schubert

et al. 2012

Neurorehabil Neural Repair

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show abstract

“…SRD was calculated as 1.96 × SEM × √2. A good measurement tool should have low SEM and low SRD values to detect changes in clinical trials [18,22,23]. The SRD% was calculated as the SRD divided by the mean of all measurements from tests 1 and 2 and multiplied by 100% to give a percentage value [24].…”

Section: Absolute Reliabilitymentioning

confidence: 99%

Influence of Testing Position on the Reliability of Hip Extensor Strength Measured by a Handheld Dynamometer

Lue

Hsieh

Liu

et al. 2009

The Kaohsiung J of Med Scie

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Hip extensors belong to an important muscle group that controls standing, walking and other functional activities. The prone position (PP) is commonly used to measure the strength of the hip extensors; however, the reliability of such measurements is poor. The aim of this study was to determine the effect of different testing positions, that is, the PP and the prone standing position (PSP), on the reliability of measurements of hip extensor strength. Intrasession reliability and interrater reliability studies were performed on 47 and 16 normal subjects, respectively. The muscle strength of the hip extensors was tested in both the PP and PSP. A handheld dynamometer and break test were used to measure the strength. Relative reliability and absolute reliability were assessed in both PP and PSP. For relative reliability, the intraclass correlation coefficient (ICC) was used to examine the level of reproducibility among measurements. Absolute reliability, the smallest real difference (SRD), was used to provide information on measurement error. The results showed that the reliability was better in PSP than in PP. For relative reliability, the values of ICCs were excellent in the intrasession reliability study, in both PP (ICC1,3 = 0.92) and PSP (ICC1,3 = 0.94). However, the interrater reliability was only excellent in PSP; the ICC2,3 were 0.92 in PSP and 0.65 in PP. For absolute reliability, the values of the SRD were much lower in PSP (29.8) than in PP (71.8), indicating that the measurement of muscle strength in PSP was more stable and had smaller measurement error than in PP. Changing the testing position from the traditional "prone" to "prone-standing" effectively improved both the relative reliability and the absolute reliability.

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“…However, a high ICC reveals little information regarding measure ment error between repeated measurements. 8 Random measurement error of a test can be quantified by absolute reliability indices, such as standard error of measurement 9 and smallest real difference (SRD) 10 (also called minimal detectable change). 11 The SEM indicates the extent of measurement error caused by chance variation in measurement.…”

mentioning

confidence: 99%

Test-Retest Reproducibility and Smallest Real Difference of 5 Hand Function Tests in Patients With Stroke

Chen

Hsueh

et al. 2009

Neurorehabil Neural Repair

360

311

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All 5 tests demonstrated satisfactory test-retest reproducibility for a diverse group of patients with stroke. However, all tests showed higher levels of measurement error when performed with the more affected hand and in patients with hypertonicity of that hand. Thus, baseline and postrehabilitation change scores using these common tests of strength and dexterity must be interpreted with some caution, especially in poorly controlled clinical trials. Repeated measures ought to be incorporated to examine reliability within a trial that includes participants with a hypertonic hand.

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The ‘smallest real difference’ as a measure of sensitivity to change: a critical analysis

Cited by 30 publications

References 0 publications

Relationship Between Motor Recovery and Independence After Sensorimotor-Complete Cervical Spinal Cord Injury

Relationship Between Motor Recovery and Independence After Sensorimotor-Complete Cervical Spinal Cord Injury

Influence of Testing Position on the Reliability of Hip Extensor Strength Measured by a Handheld Dynamometer

Test-Retest Reproducibility and Smallest Real Difference of 5 Hand Function Tests in Patients With Stroke

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