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Table 13 Results of studies assessing measurement invariance of the instruments included in the review

From: Measuring carer quality of life in Duchenne muscular dystrophy: a systematic review of the reliability and validity of self-report instruments using COSMIN

Instrument N Mean Age (SD) % female Country Analysis model Key result(s) Rating of measurement property
Rating Quality of evidence
ZBI [60] 475 44 (NR) 81 UK, US ANOVA (DIF) “Analysis of scale stability showed that there was no significant uniform differential item functioning (i.e., a systematic difference across the full range of level of burden) or nonuniform differential item functioning (i.e., nonuniformity in the differences across level of burden) by country (UK vs. US; p > 0.002 and p > 0.009) or by sex (female vs. male; p > 0.004 and p > 0.028).” + Very low
  1. Citation next to the instrument is for the study assessing this measurement property
  2. DIF, differential item functioning; NR, not reported