Reduced health care utilization after entering opioid agonist treatment; change in mental and somatic health domains

Background
Patients entering opioid agonist treatment (OAT) are known to experience both mental health and somatic health problems, but less is known about the actual health care utilization among this population within these health domains.
This project explored the change in in-patient health care utilization comparing individuals’ in-patient use one year before and the two following years after entering OAT.
 
Methods
The cohort was derived from the Norwegian Cohort of Patients in Opioid Maintenance Treatment and Other Drug Treatment (NorComt) research project, including 278 patients entering OAT during 2012-2014; a nationally representative sample.
Specialist health care utilization data stem from the Norwegian Patient Registry, a national registry of all who received health care at specialist (secondary) level. In-patient health care utilization within two domains; mental health and somatic health was included.
The proportion of patients who used/required in-patient care, and the number and mean number of days, across mental and somatic health are reported.
 
Results
Men dominated the sample (72%), with mean age at OAT entry; 39 years (SD 9.4). 
During the year prior to entering OAT; 13% had one or more in-patient hospitalizations in mental health, while the same applied for 39% regarding somatic in-patient service.
During the first and second year following OAT entry the proportion of OAT patients with in-patient days in mental health were reduced to; 10% and 8%, respectively, while for somatic health the corresponding proportions were; 31% both years. The total numbers and (mean) number of days spent as in-patients in mental health varied from 679 (19) days prior to treatment, to 760 (27) and 338 (15) days during first and second year. For somatic health the corresponding numbers were; 1201 (11) days prior to OAT, and 664 (8) and 569 (7) the two following years, representing a significant decline.
Conclusion
While OAT patients enter specialized addiction treatment, treatment efforts and cost naturally increase in these addiction services, while we observe a decline in the number of patients in need of in-patient mental and particularly somatic health care. This illustrates the ability of specialist addiction services and OAT’s potential in reducing health care expenditure in other health domains. This strain relief from OAT patients on other treatment services highlights the importance of expanding OAT, not only benefiting patients but also adjacent services.