Baumann Skin Type Questionnaire (BSTQ): creation and validation of the Polish language version – part two

Introduction:
Skin type assessment is important because it is a guidance for specialists and consumers to select and recommend the most appropriate skin care products and protocols. One easy-to-administer instrument used for skin type classification is the Baumann Skin Type Questionnaire.

Aim:
Translation and validation of the Polish version of the Baumann Skin Type Questionnaire (BSTQ) – pigmented or non-pigmented and wrinkled or tight skin.

Material and methods:
Both forward and backward translation of the English version of the BSTQ was performed. The study was conducted on 103 individuals. The respondents completed the questionnaire twice, one day after the other. The subjects participated in practical classes of facial care cosmetology which allowed for conducting interviews and skin examinations by a cosmetology expert.

Results:
The Polish version of the BSTQ demonstrated high test-retest reliability (reproducibility) in the dimension evaluating skin with or without hyperpigmentation as well as wrinkled or tight skin (ICC3 = 0.91; ICC3 = 0.97, respectively). Moreover, an excellent level of agreement between initial test and retest (pigmented vs. non-pigmented: AC1 = 1.00, 95% CI: 1.00; wrinkled vs. tight: AC1 = 0.93, 95% CI: 0.87–0.99). However, the Polish version of the BSTQ demonstrated a low internal consistency, corroborated by low Guttman’s Lambda 6 reliability (pigmented vs. non-pigmented: a_raw = 0.55, a_std = 0.54, G6 = 0.63; retest: a_raw = 0.58, a_std = 0.54, G6 = 0.63; wrinkled vs. tight: a_raw = 0.33, a_std = 0.25, G6 = 0.47; retest: a_raw = 0.36, a_std = 0.33, G6 = 0.54).

Conclusions:
The use of the BSTQ in assessing the skin for hyperpigmentation and age-related changes should be complemented by another diagnostic approach – clinical assessment before starting treatment or anti-aging interventions.