Supplementary Material for: Effect of Fluid Intake on Hydration Status and Skin Barrier Characteristics in Geriatric Patients: An Explorative Study

<b><i>Background/Aim:</i></b> Inadequate fluid intake is assumed to be a trigger of water-loss dehydration, which is a major health risk in aged and geriatric populations. Thus, there is a need to search for easy to use diagnostic tests to identify dehydration. Our overall aim was to investigate whether skin barrier parameters could be used for predicting fluid intake and/or hydration status in geriatric patients. <b><i>Methods:</i></b> An explorative observational comparative study was conducted in a geriatric hospital including patients aged 65 years and older. We measured 3-day fluid intake, skin barrier parameters, Overall Dry Skin Score, serum osmolality, cognitive and functional health, and medications. <b><i>Results:</i></b> Forty patients were included (mean age 78.45 years and 65% women) with a mean fluid intake of 1,747 mL/day. 20% of the patients were dehydrated and 22.5% had an impending dehydration according to serum osmolality. Multivariate analysis suggested that skin surface pH and epidermal hydration at the face were associated with fluid intake. Serum osmolality was associated with epidermal hydration at the leg and skin surface pH at the face. Fluid intake was not correlated with serum osmolality. Diuretics were associated with high serum osmolality. <b><i>Conclusions:</i></b> Approximately half of the patients were diagnosed as being dehydrated according to osmolality, which is the current reference standard. However, there was no association with fluid intake, questioning the clinical relevance of this measure. Results indicate that single skin barrier parameters are poor markers for fluid intake or osmolality. Epidermal hydration might play a role but most probably in combination with other tests.

<b><i>背景与研究目的：</i></b> 液体摄入不足被认为是失水性脱水的诱因，而该病症在老年及高龄人群中属于主要健康风险之一。因此，亟需探索简便易用的脱水诊断检测方法。本研究的核心目标为探究皮肤屏障参数（skin barrier parameters）能否用于预测高龄患者的液体摄入量及（或）水合状态。
<b><i>研究方法：</i></b> 本研究在某老年医院开展探索性观察对照研究，纳入年龄≥65岁的老年患者。研究人员记录了受试者3天内的液体摄入量、皮肤屏障参数、总体皮肤干燥评分（Overall Dry Skin Score）、血清渗透压（serum osmolality）、认知与功能健康状况以及用药情况。
<b><i>研究结果：</i></b> 本研究共纳入40例患者，平均年龄为78.45岁，其中女性占比65%，受试者日均液体摄入量为1747 mL。依据血清渗透压检测结果，20%的患者确诊为脱水，另有22.5%存在脱水前期风险。多变量分析结果显示，面部皮肤表面pH值（skin surface pH）与表皮水合度（epidermal hydration）与液体摄入量存在关联；血清渗透压则与腿部表皮水合度及面部皮肤表面pH值相关。液体摄入量与血清渗透压并无显著相关性，而利尿剂的使用与血清渗透压升高存在关联。
<b><i>研究结论：</i></b> 以血清渗透压作为当前临床参考金标准，约半数患者被诊断为脱水，但该诊断结果与患者的实际液体摄入量并无关联，这使得该检测指标的临床相关性受到质疑。研究结果表明，单一皮肤屏障参数无法作为液体摄入量或血清渗透压的有效标志物。表皮水合度或可在其中发挥一定作用，但大概率需要与其他检测手段联合应用方能体现临床价值。