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Table 4 Differential item functioning in the original 10-item DLQI version

From: Rasch analysis holds no brief for the use of the Dermatology Life Quality Index (DLQI) in Chinese neurodermatitis patients

Differential item functioning Results (Original 10-item DLQI)
Age Item 2: more agreement among people < 35 (p = .028)
Item 4: more agreement among people < 35 (p = .015)
Sex No DIF
Location No DIF
Education Item 4: more agreement for higher education (p = .038)
Severity of illness Item 4: more agreement for patients with more severe condition (p = .027)
Item 8: more agreement for patients with more severe condition (p = .041)
  1. The criterion for differential item function was a Mantel–Haenszel statistic with p < 0.01 after Bonferroni correction [21]. Using an uncorrected p < 0.05 is not common, but minimizes the risk of underestimating item bias. After Bonferroni correction, no differential item functioning was observed