Waiting time for treatment in Dutch mental healthcare is increasing. General practitioners substantially deviate from the allocation guideline which seems to contribute to the increase of waiting...Show moreWaiting time for treatment in Dutch mental healthcare is increasing. General practitioners substantially deviate from the allocation guideline which seems to contribute to the increase of waiting time. This study aimed to investigate whether undertreatment can be beneficial for patients and the MHC system. In addition, this study aimed to identify characteristics of undertreated patients that suffered unfavorable undertreatment based on clinical data and clinical judgement by general practitioners. Data was obtained in a naturalistic environment in a mental healthcare institution in the Netherlands and patients received treatment as usual. A total of 6193 electronic patient records were included. Exclusion criteria and missing data left 1057 cases eligible for analyses. A one-way ANOVA and a forward hierarchical binary logistic regression were conducted to investigate both aims. Results showed that undertreatment relates to worse treatment outcomes in comparison to patients in S-MHC. Unfavorable undertreatment was best predicted by waiting time and level of pre-treatment functioning. Longer waiting time is related to the need for more specialized care. Also, lower levels of pre-treatment functioning is related to the need for more specialized care. B-MHC care for undertreated patients must be improved. GPs seem to have valid reason to deviate from the allocation guideline. The allocation guideline could benefit from the addition of variables based on clinical judgement. To provide the care that undertreated patients need, treatment in B-MHC could be prolonged to match outcomes in S-MHC. Another solution could be to limit the negative effects during waiting time for patients.Show less