One way to measure the efficacy of psychiatric care is to evaluate changes in patient symptomology on standardized assessments from admission to discharge. However, current research suggests metrics of patient outcomes alone may not be enough to evaluate efficacy, and it may be helpful to consider the cost-effectiveness of the treatment journey as well. For example, if the same patient outcomes can be achieved in a shorter amount of time, patients could benefit from lowered financial burden as well as minimized disruptions to daily life. This is particularly true in the outpatient setting where the potential range in treatment duration is especially apparent. Although Partial Hospitalization Programs (PHP) are more intensive than Intensive Outpatient Programs (IOP), both types are typically 2-4 weeks long though can last much longer (e.g., 6+ months) depending on a variety of factors (e.g., diagnosis, severity, patient insurance coverage).
Current evidence on treatment duration and patient outcomes shows mixed results. While some studies in patients with a psychoactive substance abuse disorder have found no link between duration and outcomes, others have found that longer treatment durations can actually lead to more negative outcomes . Determining an evidence-based ideal duration of treatment can be challenging, but a good starting point may be to explore the association between Statistically Meaningful Improvement (SMI) on the Behavior and Symptom Identification Scale (BASIS-32™) and number of outpatient treatment sessions. Recall that with SMI, each patient’s change from admission to discharge places the patient into one of five buckets: Large Decline, Small Decline, No Effect, Small Improvement, or Large Improvement.
Overall, our data show a weak positive association between the number of treatment sessions and SMI on the BASIS-32™ in the IOP setting, where more treatment sessions are associated with more patient improvement. A negligible overall positive relationship is seen in the PHP setting. Examining these relationships by diagnostic category paints a more complete picture. Patients diagnosed with substance use or psychotic disorders seem to benefit from more treatment sessions in both treatment settings, while additional sessions in Anxiety and Nonpsychotic Disorder patients seem to not have a relationship with or perhaps have a negligible negative relationship with improvement. Improvement in Mood Disorder patients seems to vary by setting, where IOP patients show a weak positive association while PHP patients show a negligible positive association.
Given these complexities and additional factors likely at play, facilities interested in exploring “cost-effective” treatment may best benefit from a more localized analysis of treatment duration where their specific programs are analyzed in isolation to detect drivers of treatment duration and efficacy within their facility.
 De Beurs, E., Warmerdam, E., Oudejans, S., Spits, M., Dingemanse, P., De Graaf, S. D. D., De Groot, I. W., Houben, H., Kuyck, W. G. E., Noorthoorn, E. O., Nugter, M. A., Robbers, S., & Van Son, G. E. (2018). Treatment Outcome, Duration, and Costs: A Comparison of Performance Indicators Using Data from Eight Mental Health Care Providers in The Netherlands. Administration and Policy in Mental Health, 45(2), 212–223. https://doi.org/10.1007/s10488-017-0818-x
 Leung, M., Drozd, E.., & Maier, J. (2009). Impact associated with the Medicare psychiatric PPS: A study of partial hospitalization programs. Center for Medicare & Medicaid Services. https://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trends-and-Reports/Reports/downloads/Leung_PHP_PPS_2010.pdf
 Bamford, Z., Booth, P.G., McGuire, J. and Salmon, P. (2003). Treatment outcome following day care for alcohol dependency: The effects of reducing programme length. Health & Social Care in the Community, 11, 440-445. https://doi.org/10.1046/j.1365-2524.2003.00447.x
 McCusker, J., Bigelow, C., Vickers‐Lahti, M., Spotts, D., Garfield, F., & Frost, R. (1997). Planned duration of residential drug abuse treatment: Efficacy versus effectiveness. Addiction, 92, 1467-1478.