Data were abstracted on the following key variables: somatoform disorder category, sample size, type of intervention, number of and duration of sessions, type of control group, duration of follow-up, outcomes evaluated, and treatment effect. The following types of patient-centered outcomes were evaluated: a) symptoms (i.e., the study’s main measure of somatic symptom count and/or severity); b) functional status (i.e., the study’s main measure of functional impairment or quality of life); and c) psychological (i.e., either adomain specific to the disorder, such as hypochondriacal or body dysmorphic beliefs and behaviors, or a generic measure of depression, anxiety, or psychological distress). For each trial, these three outcomes were assessed as positive (outcome was better in the treatment group than the control group),
equivocal (there was a trend favoring the treatment group but the group difference was not statistically significant), negative (the groups did not differ), or not assessed. Secondary variables for which data were abstracted
include patient demographics (age, gender, educational level, race), and country as well as type of clinic in which the study was conducted.