Although we tested for several potential confounding relationships, there may be other confounding variables that were not assessed in both the NLAES and the NESARC. In addition, potential explanatory variables, such as physical activity, caloric intake, binge-eating behaviors, and other psychiatric disorders were not measured. However, in order for the secular trend to be attributable to and unmeasured confounding variable, it would be necessary for the unmeasured variable to be correlated with both family history of alcoholism, and with obesity, and to have changed over time. This same principle applies in biases inherent in self-reports of height, weight, and family history of alcoholism. In other words, presuming such biases are stable over time, they are unlikely to account for the secular trend in the association between FH-Alc and obesity.
