2:45 PM - 3:00 PM
[3Fp-03] Use of Change-point Regression Models to Analyze the Effects of Functional Foods
Keywords:Change-point Regression Models, Functional food, Adlay, Stratum corneum water, Human clinical trial
【Purpose】
In functional food intervention studies, the study population is often a mixed population of healthy individuals and/or less healthy but not sick people. For such populations, the intervention effects of food are not constant. Change-point Regression Models (CPRMs) have been proposed to address this heterogeneity. CPRM an analytical method that takes into account the point of change by the treatment, and analyze the effect of treatment. However, efficacy of CPRM for preventive effects has not been examined. In this study, CPRM was applied to the data from a study of stratum corneum water content (SCWC) by Adlay tea intervention to examine the preventive effect analysis by CPRM.
【Methods】
We examined whether the pre-value affects the post-value regarding the decrease in SCWC of the study subjects using the following CPRM model formula.
yi = α + β1xi + β2 I(xi > xcp)(xi - xcp)(1 - gi) + εi
Here, xi; the pre value of the ith subject, yi ; the post value, gi; group information (Adlay tea group = 1, Placebo group = 0) and xcp; the point of change, I(·);an indicator function (1 when xi > xcp is true and 0 otherwise).
【Results】
CPRM analysis revealed the point of change in the pre-value of SCWC at 24.8 (a.u.). Above this point of change, a significant suppression of SCWC reduction was observed in the Adlay tea group compared to the placebo group, and thus pre-value influenced the effectiveness of Adlay tea intervention. It was predicted that the point of change appeared because when the pre-value of SCWC was below a certain threshold, further reduction in water content was less likely to occur. CPRM is applicable not only to pre-values but also to other factors such as age, and it is expected to be effective in the analysis of intervention studies of functional foods.
In functional food intervention studies, the study population is often a mixed population of healthy individuals and/or less healthy but not sick people. For such populations, the intervention effects of food are not constant. Change-point Regression Models (CPRMs) have been proposed to address this heterogeneity. CPRM an analytical method that takes into account the point of change by the treatment, and analyze the effect of treatment. However, efficacy of CPRM for preventive effects has not been examined. In this study, CPRM was applied to the data from a study of stratum corneum water content (SCWC) by Adlay tea intervention to examine the preventive effect analysis by CPRM.
【Methods】
We examined whether the pre-value affects the post-value regarding the decrease in SCWC of the study subjects using the following CPRM model formula.
yi = α + β1xi + β2 I(xi > xcp)(xi - xcp)(1 - gi) + εi
Here, xi; the pre value of the ith subject, yi ; the post value, gi; group information (Adlay tea group = 1, Placebo group = 0) and xcp; the point of change, I(·);an indicator function (1 when xi > xcp is true and 0 otherwise).
【Results】
CPRM analysis revealed the point of change in the pre-value of SCWC at 24.8 (a.u.). Above this point of change, a significant suppression of SCWC reduction was observed in the Adlay tea group compared to the placebo group, and thus pre-value influenced the effectiveness of Adlay tea intervention. It was predicted that the point of change appeared because when the pre-value of SCWC was below a certain threshold, further reduction in water content was less likely to occur. CPRM is applicable not only to pre-values but also to other factors such as age, and it is expected to be effective in the analysis of intervention studies of functional foods.