Reliability of the skin blotting method when used on the elderly

The aim of this study was to compare protein secretion on intact skin of extremities and verify the relationship between the marker proteins on abdominal skin and systemic factors using skin blotting. A cross‐sectional study was conducted among elderly patients aged 65 years and older (N = 73) at a long‐term medical facility in Japan. Skin blotting was performed on the right and left forearms, right and left lower legs, and abdomen. Pearson's correlations and Bland–Altman plots were utilised for comparing the protein secretion from the skin between the right or left forearms or lower legs. Multiple regression analysis was applied to determine the relationship between intensity levels of 3 proteins on the abdominal skin and the systemic factors. Bland–Altman plots demonstrated that there was no significant difference between right and left secretion levels on the forearms and lower legs among 3 proteins. Multiple regression analysis showed that age and antiplatelet use was positively associated with decreased collagen type IV and increased matrix metalloproteinase 2 levels, respectively. Our findings suggested that collecting samples from either the right or the left skin would be sufficient if skin properties between arms and legs are evaluated using skin blotting.