A study published in the Clinical, Cosmetic and Investigational Dermatology indicated that both  self-assessed questionnaire and lactic acid sting test (LAST) should be used for procuring more information from the people to discern their sensitive skin type. The questionnaire is related to sensitive skin presented as red and oily face without weakened barrier function. For identification of fragile skin barrier and improved blood flow on the face, LAST scores are appropriate,

Yao Pan et al. undertook this cross-sectional study for estimating the biophysical properties of sensitive skin assessed by questionnaire and LAST by noninvasive instruments. In both healthy and sensitive populations, an association of LAST scores and questionnaires with the biophysical parameters was examined.

Overall, 209 healthy Chinese female volunteers (age 18–35 years) took part in the study. For identifying sensitive skin, both self-assessment questionnaires and LAST were carried out. The epidermal biophysical properties, including skin hydration, sebum content, transepidermal water loss (TEWL), erythema index (erythema index), a* value, L* value, pH and elasticity of the skin, were estimated via noninvasive instruments.

The prevalence of sensitive skin was witnessed to be dependent on the diagnostic method. The frequency of sensitive skin as per questionnaire and LAST is shown in Table 1: 

People having self-evaluated sensitive skin exhibited a slightly greater LAST positive rate. In the self-evaluated sensitive skin group, the sebum content, skin hydration, a* value, and erythema index values were considerably greater. On the other hand, a* value, erythema index values and TEWL elevated, but L* value substantially dropped in the LAST positive group.

The LAST stingers among sensitive skin people exhibited raised erythema index but not in people with healthy skin. Furthermore, the questionnaire scores were noted to be positively associated with sebum content, erythema index value, skin hydration, and a* value, while a positive association of LAST scores with erythema index value, TEWL, and a* value was witnessed.

Both the scores of the questionnaire and LAST were found to be linked with the L* value. The biophysical parameters linked with different sensitive skin assessment methods will aid to develop an integrated and personalized evaluation system, concluded the investigators.