Waiting Time from Referral to Intake and Its Clinical Implications: Routine Outcome Monitoring Data from a Large Dutch Outpatient Clinic

Background: Long waiting times remain a key barrier to accessing outpatient mental health care in the Netherlands and worldwide. Little is known about patterns of symptom change during waiting times and whether certain individuals are at greater risk of deterioration. This brief report used routine outcome monitoring data from Dutch outpatient clinics to examine changes in psychological distress during waiting and to test whether age, sex, socioeconomic status, and length of waiting predicted improvement or worsening. Methods: Routine outcome monitoring data were analyzed from 962 individuals referred by their general practitioner to a large Dutch outpatient mental health provider. Psychological distress was assessed with the Symptom-Questionnaire-48 (SQ-48), which participants completed at both referral and intake. We computed reliable Change Indices (RCI) to classify individuals as improved, deteriorated, or unchanged. Logistic and multinomial logistic regression were used to examine the effects of waiting time, socioeconomic status, age, and sex on change status during waiting times. Results: Mean SQ-48 scores decreased significantly between referral and intake, but changes were not clinically meaningful. Most patients (92.02%) showed no reliable change; 6.03% deteriorated, and 1.35% improved. Waiting time, sex, age, and socioeconomic status did not predict symptom change during waiting time. Limitations include the relatively short average waiting time (M = 18.90 days), limited variability in socioeconomic status, and potential systematic dropout. Conclusions: Most individuals remained stable, with only small proportions showing reliable improvement or deterioration during short waiting times. These findings highlight the need for precision-based approaches to identify those at risk of worsening.