Abstract
PURPOSE: This longitudinal study examined how pre-intervention psychological health helps predict bariatric surgery (BS) success as percentage of expected body mass index loss (%EBMIL) over shorter to longer periods. METHODS: Adult candidates for BS (N = 334, 67.4% females) completed the Symptoms Checklist 90 (SCL-90) questionnaire; on average, 11 months occurred between the pre-surgery psychological evaluations and the bariatric intervention. We explored the factor structure of the SCL-90 items and inspected how SCL-90 empirical factors compared with SCL-90 scales and general indices predicted %EBMIL at 3-6-month, 1-year, and 2-year follow-up occasions, adjusting for gender, pre-intervention use of antidepressants and actual and ideal BMIs. RESULTS: Factor analysis combined the 90 items into 8 factors, which partially replicated the expected item structure. The SCL-90 empirical factors (but not the SCL-90 scales and indices) contributed to predict BS success. In fact, the Relational Distress factor directly protected from weight regain at 1-year follow-up, indirectly via 1-year %EBMIL at the 2-year follow-up, when it further strengthened the impact of the empirical factor of Generalized Anxiety on the 2-year BS outcome. The results also evidenced a cascade effect of the pre-surgery actual BMI across time as well as unique and direct effects of pre-surgery use of antidepressants and perceived ideal BMI on the 2-year outcome. CONCLUSIONS: SCL-90 empirical factor scores for obese patients are more efficient in anticipating BS success compared with original scale scores. They reveal that relational distress and anxiety are risk factors for postoperative weight loss, in addition to pre-intervention actual BMI, antidepressant therapy, and perceived ideal BMI. LEVEL OF EVIDENCE: III, well-designed cohort.