The role of dual diagnosis in health-related quality of life among treatment-seeking patients in Spain

The comorbidity of any substance use disorder and another mental disorder is defined as dual diagnosis. Dual diagnosis is very common and clinical and therapeutic consequences have been described. This cross-sectional study aimed to analyse health-related quality of life (HRQoL) according to clinical characteristics and psychiatric comorbidities in patients with substance dependence.

A total of 1276 substance-dependent patients seeking treatment were recruited. HRQoL was evaluated by the Short-Form 36 (SF-36) questionnaire. The SCID-I, SCID-II and Conners’ adult ADHD diagnostic interview were used to evaluate dual diagnosis. A visual analogue scale was used to measure craving. Bivariate and multivariate analyses were performed, and correction for multiple tests was conducted.

Substance-dependent patients had impaired quality of life, especially in the mental component. SF-36 physical and mental component scores were 47.7 ± 10.9 and 36.1 ± 14.1, respectively. Furthermore, 65% of the patients had dual diagnosis, 51% had an Axis I DSM-IV-TR mental disorder and 35% had some personality disorder. Impaired physical quality of life was independently associated with medical condition, age, being female, depressive disorder and anxiety disorder. Depression disorder, any personality disorder, active consumption last month, Attention deficit hyperactivity disorder, anxiety disorder, suicide attempt were independently associated with worse mental quality of life.

These findings emphasize the significance of dual diagnosis in the impairment of HRQoL in substance-dependent patients, particularly with regard to mental component. In addicted patients with low scores on SF-36, psychiatric comorbidity should be evaluated and treated in an integrated approach.