schizophrenia affects approximately 2.4 million people in the united states ( about 1.1% of the population 18 years of age ) and is associated with high direct healthcare costs , estimated at $ 22.7 billion in 2002 ( $ 48.4 billion in 2014 when adjusted for inflation using the us consumer price index medical care category ) [ 13 ] . the high cost of schizophrenia treatment is due to the chronic nature of the disease and the frequent occurrence of relapses . rates of schizophrenia relapse have been reported as high as 80% at 12 months following treatment discontinuation . relapses often require hospitalization , which contributes substantially to the total healthcare costs associated with this disease . antipsychotic treatment benefits patients by reducing the risk of relapse , but even partial nonadherence increases the risk of relapse - related hospitalizations . despite the importance of adherence , 74% of schizophrenia patients are nonadherent to oral antipsychotics according to an 18-month study . long - acting injectable ( lai ) formulations of antipsychotic agents were developed with the primary aim of improving the treatment adherence of patients with schizophrenia , and thus preventing relapse , by providing sustained medication coverage to patients over the duration of the injectable . lai treatment reduced the risk of rehospitalization compared with oral medication in a pair - wise comparison following hospital discharge   and resulted in a reduction in hospitalizations and schizophrenia relapses following initiation of lai compared with oral medication . patients who initiated lais have also been shown to incur lower healthcare costs as a result of fewer hospitalizations , an outcome that encompasses all age groups , including young adults . however , there are conflicting data on the comparative effectiveness of oral medications compared with lais in reducing the risk of relapse . in a recent randomized clinical trial , lai risperidone did not confer an advantage over oral medication for relapse or hospitalization but did provide some advantage for psychotic symptoms . the conflicting data highlight the need for continued evidence generation on the value of lais over oral antipsychotic medications . aripiprazole once - monthly ( aom ) is the first dopamine partial agonist available in a long - acting formulation and has been approved for treatment of schizophrenia by the us food and drug administration . in a recent study of patients with schizophrenia , additionally , in a separate multicenter , open - label , mirror - image study of patients with schizophrenia , aom was reported to reduce total psychiatric hospitalizations among patients who switched from oral standard of care ( soc ) therapy to aom ( aom mirror - image study ; nct01432444 ) . in that study , hospitalization rates were reduced from 38.1% ( 165/433 ) during the soc 6-month retrospective period , compared with 8.8% ( 38/433 ) during the aom 6-month prospective period ( p<0.0001 ) . given the increasing pressure from payers to improve patient outcomes while containing costs , it is important to understand the impact of aom treatment initiation on medical costs related to psychiatric hospitalizations and antipsychotic pharmacy costs . in the current study , a decision model was developed to estimate costs associated with aom treatment initiation using the clinical data gathered in the aom mirror - image study . additionally , because previous hospitalizations are predictive of future schizophrenia - related hospital admissions , the decision model evaluated cost - saving opportunities among a subset of patients who had at least one psychiatric hospitalization prior to aom treatment initiation . the patient population for this analysis was the population investigated in the multicenter , open - label aom mirror - image study ; specifically , patients were 1865 years of age with schizophrenia who switched from oral soc antipsychotic therapy ( retrospective period ) to aom ( prospective period ) in a naturalistic community setting in north america . in both the retrospective and prospective phases , the majority of patients were male ( 73.5 and 69.5% ) and approximately half of the patients were white ( 46.2 and 49.9% ) . at baseline for the 2 study phases , patients had a mean age of 42.7 and 42.1 years and a mean bmi of 30.4 and 30.8 kg / m . patients entering the prospective period had moderate disease severity ( cgi - s scale 3.90.8 ) at baseline for the prospective period . a decision model was designed to compare costs based on data obtained from the retrospective period of the aom mirror - image study with costs based on data obtained from the prospective period . in the full study population group , 433 patients received oral soc treatment in the 6-month retrospective period and then switched to aom for the 6-month prospective period . in addition to this full study population , a subset of 165 patients from the aom mirror - image study who had 1 psychiatric hospitalization during the retrospective period was also analyzed ; among all patients who relapsed during the retrospective soc period ( n=19 ) , 11.5% relapsed during the prospective aom treatment period . a microsoft excel - based decision model was developed to compare psychiatric hospitalization - related medical and antipsychotic treatment costs before and after aom treatment initiation based on the results of the mirror - image study . per - patient costs ( drug costs and psychiatric hospitalization - related charged amounts ) were estimated during the pre- and post - aom initiation period : the 6-month retrospective period during which patients received oral soc and the 6-month prospective period during which patients received aom after switching treatment from oral soc to aom ( figure 1 ) . the probability of psychiatric hospitalizations and number of hospitalizations ( among those hospitalized ) were obtained from the aom mirror - image study . complete data for the 6-month retrospective period were available for the full study population ( 433 patients ) and for the subset of 165 patients who experienced at least one psychiatric hospitalization during the 6-month retrospective period ( table 1 ) . similar data were collected for patients in the 6-month prospective period while on aom ; however , due to discontinuations from the clinical trial during the 6-month prospective period , complete data on psychiatric hospitalizations were not available for all patients during this period . during the prospective period , patients stayed on aom for an average of 4.93 months prior to discontinuing from the study . , 140 out of 433 patients ( 32.3% ) discontinued aom at the end of 6 months of the study . because patients were not on aom for the entire 6 months and remained on aom for a mean of 4.93 months before discontinuing treatment or exiting the study , estimates of the probability of hospitalization and number of hospitalizations among those hospitalized were calculated for the remaining 1.07 months using data from the retrospective period as a proxy . specifically , the percentage of patients experiencing a psychiatric hospitalization after discontinuation of aom ( 6.08% ) was derived by multiplying the percentage of hospitalizations in the retrospective period ( 38.11% )   by 0.178 ( 1.07 months divided by 6 months ) . the number of psychiatric hospitalizations among those hospitalized after discontinuation of aom was estimated to be 1.04 ( table 1 ) . costs were obtained from publicly available sources and were used to calculate cost for drug and hospitalization charged amounts ( summarized in table 2 ) . pharmacy acquisition costs for oral aripiprazole and aom as well as oral soc were obtained ; the cost used for oral soc was a simple average of generic pricing for fluphenazine , olanzapine , risperidone , quetiapine , and ziprasidone . average hospitalization charges for a psychiatric hospitalization were obtained , and the same cost per hospitalization was applied to hospitalizations in both the retrospective and prospective periods . charges represent the amount per hospitalization charged to the payer , whereas actual reimbursement may vary by health plan . in the kane study , patients were first stabilized on oral aripiprazole during the oral conversion phase prior to initiating aom . due to the unavailability of tolerability data during the retrospective period , this model did not compare adverse events experienced before and after aom treatment initiation . however , during the prospective period , patients may have discontinued aom treatment due to adverse events and this is factored into the calculation of hospitalization rates after aom initiation . costs and outcomes per patient over 6 months were estimated for the retrospective period and the prospective period ( figure 1 ) . per - patient model results were presented as drug costs , hospital charges , total costs ( drug costs plus hospital charges ) , number of hospitalizations , and hospitalization days . additionally , incremental cost - effectiveness ratio ( icer ) per hospital day avoided over a 6-month period was calculated as : 
 icer = total  cost  accrued  when  on  soc+aomtotal  cost  accrued  when  on  sochospital  days  when  on  sochospital  days  when  on  soc+aom sensitivity analysis was performed to test the robustness of the model s assumptions and specific parameter estimates , given their uncertainty . one - way sensitivity analysis in which one parameter value is varied at a time while all others are held constant was performed for the following model parameters : time on aom , cost per month on oral medication , percentage of patients with a psychiatric hospitalization in both the retrospective and prospective periods , number of psychiatric hospitalizations among those hospitalized in both the retrospective period and prospective period , hospital length of stay , and cost per psychiatric hospitalization . variation in these parameter values was based on 95% cis or assumption ( where data did not exist ) ( tables 1 and 2 ) . additionally , a probabilistic sensitivity analysis in which the impact of varying all of the above parameters simultaneously according to prespecified distributions was conducted . specifically , a second - order monte carlo simulation was conducted , in which variability was examined over 10,000 iterations . for example , 95% cis were estimated for the number of psychiatric hospitalizations , given standard error and assuming a gamma distribution . given the sample size and assuming a beta distribution , 95% cis were also calculated for the percentage of patients with psychiatric hospitalizations . for time on therapy , 95% ci was estimated assuming a normal distribution and using the standard error from the clinical trial . cost of oral antipsychotics and average hospital length of stay were varied by 20% of base - case values while average hospital charges were varied by 50% . for the one - way sensitivity analysis , the impact on the incremental cost per hospital day avoided for each parameter was then ranked from most sensitive to least sensitive and plotted in the form of a tornado diagram . for the probabilistic sensitivity analysis , the impact on the incremental total costs was presented in a histogram . the patient population for this analysis was the population investigated in the multicenter , open - label aom mirror - image study ; specifically , patients were 1865 years of age with schizophrenia who switched from oral soc antipsychotic therapy ( retrospective period ) to aom ( prospective period ) in a naturalistic community setting in north america . in both the retrospective and prospective phases , the majority of patients were male ( 73.5 and 69.5% ) and approximately half of the patients were white ( 46.2 and 49.9% ) . at baseline for the 2 study phases , patients had a mean age of 42.7 and 42.1 years and a mean bmi of 30.4 and 30.8 kg / m . patients entering the prospective period had moderate disease severity ( cgi - s scale 3.90.8 ) at baseline for the prospective period . a decision model was designed to compare costs based on data obtained from the retrospective period of the aom mirror - image study with costs based on data obtained from the prospective period . in the full study population group , 433 patients received oral soc treatment in the 6-month retrospective period and then switched to aom for the 6-month prospective period . in addition to this full study population , a subset of 165 patients from the aom mirror - image study who had 1 psychiatric hospitalization during the retrospective period was also analyzed ; among all patients who relapsed during the retrospective soc period ( n=19 ) , 11.5% relapsed during the prospective aom treatment period . a microsoft excel - based decision model was developed to compare psychiatric hospitalization - related medical and antipsychotic treatment costs before and after aom treatment initiation based on the results of the mirror - image study . per - patient costs ( drug costs and psychiatric hospitalization - related charged amounts ) were estimated during the pre- and post - aom initiation period : the 6-month retrospective period during which patients received oral soc and the 6-month prospective period during which patients received aom after switching treatment from oral soc to aom ( figure 1 ) . the probability of psychiatric hospitalizations and number of hospitalizations ( among those hospitalized ) were obtained from the aom mirror - image study . complete data for the 6-month retrospective period were available for the full study population ( 433 patients ) and for the subset of 165 patients who experienced at least one psychiatric hospitalization during the 6-month retrospective period ( table 1 ) . similar data were collected for patients in the 6-month prospective period while on aom ; however , due to discontinuations from the clinical trial during the 6-month prospective period , complete data on psychiatric hospitalizations were not available for all patients during this period . during the prospective period , patients stayed on aom for an average of 4.93 months prior to discontinuing from the study . based on kane et al . , 140 out of 433 patients ( 32.3% ) discontinued aom at the end of 6 months of the study . because patients were not on aom for the entire 6 months and remained on aom for a mean of 4.93 months before discontinuing treatment or exiting the study , estimates of the probability of hospitalization and number of hospitalizations among those hospitalized were calculated for the remaining 1.07 months using data from the retrospective period as a proxy . specifically , the percentage of patients experiencing a psychiatric hospitalization after discontinuation of aom ( 6.08% ) was derived by multiplying the percentage of hospitalizations in the retrospective period ( 38.11% )   by 0.178 ( 1.07 months divided by 6 months ) . the number of psychiatric hospitalizations among those hospitalized after discontinuation of aom was estimated to be 1.04 ( table 1 ) . costs were obtained from publicly available sources and were used to calculate cost for drug and hospitalization charged amounts ( summarized in table 2 ) . pharmacy acquisition costs for oral aripiprazole and aom as well as oral soc were obtained ; the cost used for oral soc was a simple average of generic pricing for fluphenazine , olanzapine , risperidone , quetiapine , and ziprasidone . average hospitalization charges for a psychiatric hospitalization were obtained , and the same cost per hospitalization was applied to hospitalizations in both the retrospective and prospective periods . charges represent the amount per hospitalization charged to the payer , whereas actual reimbursement may vary by health plan . in the kane study , patients were first stabilized on oral aripiprazole during the oral conversion phase prior to initiating aom . due to the unavailability of tolerability data during the retrospective period , this model did not compare adverse events experienced before and after aom treatment initiation . however , during the prospective period , patients may have discontinued aom treatment due to adverse events and this is factored into the calculation of hospitalization rates after aom initiation . costs and outcomes per patient over 6 months were estimated for the retrospective period and the prospective period ( figure 1 ) . per - patient model results were presented as drug costs , hospital charges , total costs ( drug costs plus hospital charges ) , number of hospitalizations , and hospitalization days . additionally , incremental cost - effectiveness ratio ( icer ) per hospital day avoided over a 6-month period was calculated as : 
 icer = total  cost  accrued  when  on  soc+aomtotal  cost  accrued  when  on  sochospital  days  when  on  sochospital  days  when  on  soc+aom sensitivity analysis was performed to test the robustness of the model s assumptions and specific parameter estimates , given their uncertainty . one - way sensitivity analysis in which one parameter value is varied at a time while all others are held constant was performed for the following model parameters : time on aom , cost per month on oral medication , percentage of patients with a psychiatric hospitalization in both the retrospective and prospective periods , number of psychiatric hospitalizations among those hospitalized in both the retrospective period and prospective period , hospital length of stay , and cost per psychiatric hospitalization . variation in these parameter values was based on 95% cis or assumption ( where data did not exist ) ( tables 1 and 2 ) . additionally , a probabilistic sensitivity analysis in which the impact of varying all of the above parameters simultaneously according to prespecified distributions was conducted . specifically , a second - order monte carlo simulation was conducted , in which variability was examined over 10,000 iterations . for example , 95% cis were estimated for the number of psychiatric hospitalizations , given standard error and assuming a gamma distribution . given the sample size and assuming a beta distribution , 95% cis were also calculated for the percentage of patients with psychiatric hospitalizations . for time on therapy , 95% ci was estimated assuming a normal distribution and using the standard error from the clinical trial . cost of oral antipsychotics and average hospital length of stay were varied by 20% of base - case values while average hospital charges were varied by 50% . for the one - way sensitivity analysis , the impact on the incremental cost per hospital day avoided for each parameter was then ranked from most sensitive to least sensitive and plotted in the form of a tornado diagram . for the probabilistic sensitivity analysis , in the overall population , the proportion of patients experiencing psychiatric hospitalization was reduced in the prospective phase compared with the retrospective phase , the mean number of hospitalizations per patient was reduced from 0.47 to 0.17 after aom initiation , and mean hospital days per patient decreased from 5.23 to 1.95 . as a result , the increase in drug costs in the prospective period ( $ 7,943 ) was offset by a reduction in hospitalization charges ( $8,990 ) ( figure 2 ) . total cost in the prospective period ( $ 13,708 ) was lower than that in the retrospective period ( $ 14,754 ) by $ 1,046 per patient , and the incremental cost per hospital day avoided for the overall population was $319 , where aom was dominant ( more effective and less costly ) . for the subset of 165 patients who had 1 prior hospitalization , the mean number of hospitalizations per patient was reduced from 1.23 to 0.29 after aom initiation and the mean number of hospital days per patient decreased from 13.72 to 3.25 . as with the full population , increased drug costs in the prospective period ( $ 8,308 ) were offset by a reduction in hospital charges ( $28,660 ) ( figure 3 ) . total cost in the prospective period ( $ 17,647 ) was 54% ( $ 20,353 ) lower than the cost per patient in the retrospective period ( $ 38,000 ) , and the incremental cost per hospitalization day avoided was $1,943 , where aom was again dominant . for the one - way sensitivity analysis , the tornado diagram for the base population shows that the results were most sensitive to the costs per psychiatric hospitalization ( figure 4a ) . specifically , decreasing the cost per psychiatric hospitalization to its lower bound increased the cost to avoid a hospital day up to $ 874 . decreasing the number of hospitalizations or the percentage of patients with a hospital stay in the retrospective period to their lower bounds also resulted in slightly positive costs per hospital day ( $ 14 and $ 143 , respectively ) however , these costs are still much lower than the average psychiatric - hospitalization cost per day , estimated at $ 2,736 ( cost of $ 30,536/length of stay of 11.16 days ) . cost savings were robust to variation in all other parameters . in the subgroup of patients who experienced a hospitalization in the retrospective phase , the one - way sensitivity analysis showed that results were most sensitive to variation in hospitalization costs ( figure 4b ) . decreasing hospitalization costs decreased the cost savings of aom ; however , the aom strategy remained less costly in all individual parameter variations . for the probabilistic sensitivity analysis in the full study population , aom remained cost saving in over 60% of cases ( figure 5a ) . aom was cost saving in all iterations for the subpopulation analysis in patients who experienced a hospitalization in the retrospective phase ( figure 5b ) . in the overall population , the proportion of patients experiencing psychiatric hospitalization was reduced in the prospective phase compared with the retrospective phase , the mean number of hospitalizations per patient was reduced from 0.47 to 0.17 after aom initiation , and mean hospital days per patient decreased from 5.23 to 1.95 . as a result , the increase in drug costs in the prospective period ( $ 7,943 ) was offset by a reduction in hospitalization charges ( $8,990 ) ( figure 2 ) . total cost in the prospective period ( $ 13,708 ) was lower than that in the retrospective period ( $ 14,754 ) by $ 1,046 per patient , and the incremental cost per hospital day avoided for the overall population was $319 , where aom was dominant ( more effective and less costly ) . for the subset of 165 patients who had 1 prior hospitalization , the mean number of hospitalizations per patient was reduced from 1.23 to 0.29 after aom initiation and the mean number of hospital days per patient decreased from 13.72 to 3.25 . as with the full population , increased drug costs in the prospective period ( $ 8,308 ) were offset by a reduction in hospital charges ( $28,660 ) ( figure 3 ) . total cost in the prospective period ( $ 17,647 ) was 54% ( $ 20,353 ) lower than the cost per patient in the retrospective period ( $ 38,000 ) , and the incremental cost per hospitalization day avoided was $1,943 , where aom was again dominant . for the one - way sensitivity analysis , the tornado diagram for the base population shows that the results were most sensitive to the costs per psychiatric hospitalization ( figure 4a ) . specifically , decreasing the cost per psychiatric hospitalization to its lower bound increased the cost to avoid a hospital day up to $ 874 . decreasing the number of hospitalizations or the percentage of patients with a hospital stay in the retrospective period to their lower bounds also resulted in slightly positive costs per hospital day ( $ 14 and $ 143 , respectively ) . however , these costs are still much lower than the average psychiatric - hospitalization cost per day , estimated at $ 2,736 ( cost of $ 30,536/length of stay of 11.16 days ) . in the subgroup of patients who experienced a hospitalization in the retrospective phase , the one - way sensitivity analysis showed that results were most sensitive to variation in hospitalization costs ( figure 4b ) . decreasing hospitalization costs decreased the cost savings of aom ; however , the aom strategy remained less costly in all individual parameter variations . for the probabilistic sensitivity analysis in the full study population , aom remained cost saving in over 60% of cases ( figure 5a ) . aom was cost saving in all iterations for the subpopulation analysis in patients who experienced a hospitalization in the retrospective phase ( figure 5b ) . initiation of lai treatment has been shown to reduce schizophrenia relapses   and hospitalizations [ 1114 ] . have demonstrated that aom delayed time to relapse   and that switching to aom from oral soc reduced hospitalizations in patients with schizophrenia . in addition to its clinical benefits , prevention of relapse in patients with schizophrenia may also reduce the economic burden of this costly disease . due to the need to improve patient outcomes while minimizing costs , it is important to understand the impact of aom treatment on psychiatric hospitalization - related costs as evaluated in the kane et al . study . utilizing the patient information provided by the kane mirror - image study , which evaluated hospitalizations during a 6-month time frame in patients 1865 years of age with schizophrenia who switched from oral soc antipsychotic therapy ( retrospective period ) to aom ( prospective period ) , we have shown that aom treatment may result in a cost - of - care savings opportunity . although schizophrenia is a chronic , debilitating condition and a 6-month observation window does not evaluate the long - term impact of aom , these data are important given that health plans , physicians , and hospital networks focus on healthcare effectiveness data and information set ( hedis ) quality measures of 30-day readmission rates for patients with schizophrenia . drug costs and psychiatric - hospitalization costs associated with aom as a treatment strategy for preventing relapse are less than corresponding costs associated with oral soc therapy . additionally , hospitalizations and hospital days were both reduced following a switch from oral soc to aom . when considering parameter uncertainty , the model was most sensitive to the cost of psychiatric hospitalizations . even when the cost of hospitalizations was at its extreme values and disadvantaged aom treatment , the incremental cost per hospital day avoided was less than the cost of being in the hospital for an additional day . in addition , in all cases of parameter variation , aom remained the more effective treatment . similar to our study , other cost studies have shown a cost benefit of using lais . a hong kong study reporting a predictive model using linear regression based on generalized estimating equations showed that risperidone lai was associated with reductions in hospitalization costs of 24.7% and hospitalization days of 10.1% , compared with a decrease of 40% for both hospitalizations and hospitalization days in the current study . other recent risperidone mirror - image studies in finland , taiwan , and new zealand have shown cost benefit in starting lai treatment [ 2729 ] , although benefits were compromised by longer bed stay   and increased utilization of outpatient services . all of the patients in the current study switched from oral antipsychotics to aom , which was not necessarily the case in the other lai mirror - image cost studies that have been reported . as a result , this analysis may provide a better approximation of the impact of switching to aom that a patient may observe as compared with previous mirror - image studies , which may have had a proportion of patients already on lais . patients with schizophrenia have a known high risk of nonadherence to treatment , and lais were developed to improve treatment adherence in these patients . in addition to the sustained drug coverage of long - acting dosage forms , patients treated with lais are closely monitored because they must visit the clinic every 16 weeks . interaction with healthcare professionals during these visits may facilitate treatment adherence , which may reduce the risk of future relapses and hospitalizations . because treatment nonadherence is greater in the real - world setting than in a controlled clinical - trial setting in which patients are closely monitored and have several incentives to adhere to their study medications , head - to - head clinical trials of lais compared with oral antipsychotics may not provide insight into the value of lais in the presence of patient nonadherence . on the other hand , real - world observational studies comparing lais with oral antipsychotics pose challenges related to study design due to the selection bias of sicker schizophrenia patients , who are likely to receive lais compared to oral antipsychotics . comparative effectiveness studies using multivariable analyses and statistical matching techniques may not be sufficient to account for the inherent clinical and disease - severity differences between patients initiating treatment with lais or oral therapies . mirror - image study designs that evaluate the change in patient outcomes before and after lai initiation may be useful for understanding the value of lais ; however , it is important to note the limitations of the aom mirror - image study design in that each patient served as his or her own control without a parallel active - control group . as a result , it can not be determined if other treatments ( other lais , oral antipsychotics ) may have a similar effect . another limitation is that in this study design , it can be difficult to separate drug treatment effects from trial effects . therefore , results may be influenced by independent factors , including admission patterns , insurance coverage , hospital bed availability , and community support . additionally , as the study was not blinded , any influence of the study design on the clinical decision to hospitalize or not to hospitalize a given patient can not be determined . it is unknown what the impact of these limitations may be and it may be possible to focus future studies to resolve these limitations . in addition to limitations due to study design , the analysis evaluated only two aspects of the cost of care for patients with schizophrenia : those for antipsychotic medication and those for hospitalization . although the prices of drugs and hospitalizations are expected to be the largest cost drivers in this patient population , due to lack of data on resource utilization such as emergency room visits , physician visits , and occurrence of adverse events during the retrospective and prospective phases , costs for these parameters were not included in the economic model . results from this economic model estimating the costs associated with psychiatric hospitalizations indicate that aom treatment presents a potential cost - saving opportunity for health plans . the higher cost of drug is more than offset by cost savings due to fewer psychiatric hospitalizations , especially in a subset of patients with 1 previous psychiatric hospitalization . the use of aom to prevent relapses may reduce the cost of care . as such
background : schizophrenia is associated with high direct healthcare costs due to progression of disease and frequent occurrence of relapses . 
 aripiprazole once - monthly ( aom ) has been shown to reduce total psychiatric hospitalizations among patients who switched from oral standard of care ( soc ) therapy to aom in a multicenter , open - label , mirror - image study of patients with schizophrenia . because of the increasing need to improve patient outcomes while containing costs , it is important to understand the impact of aom treatment initiation on medical costs associated with psychiatric hospitalizations and antipsychotic pharmacy costs.methods:in the current study , an economic model was developed using data from the aom mirror - image study to evaluate the psychiatric hospitalization - related medical costs and antipsychotic pharmacy costs during a 6-month period before ( retrospective period ) and after ( prospective period ) the aom treatment initiation . 
 the economic model evaluated cost - saving potential of aom among all patients ( n=433 ) as well as a subset of patients with 1 prior hospitalization ( n=165 ) who switched from oral soc to aom . 
 unit cost data were obtained from publicly available sources.results:both hospitalizations and hospital days were reduced following a switch from oral soc to aom . as a result , psychiatric hospitalization - related costs were lower during the prospective period when compared with the retrospective period . 
 furthermore , the increase in antipsychotic pharmacy costs due to switching from oral soc to aom was offset by a reduction in psychiatric hospitalization - related medical costs . per - patient costs 
 were reduced by $ 1,046 ( usd ) in the overall population and by $ 20,353 in a subset of patients who had at least 1 psychiatric hospitalization during the retrospective period . 
 results were most sensitive to changes in hospitalization costs.conclusions:aom is associated with reducing the risk of relapse among patients with schizophrenia . 
 the increase in antipsychotic pharmacy costs due to switching from oral soc to aom was offset by a reduction in costs associated with psychiatric hospitalizations , thereby presenting a cost - saving opportunity for health plans .