Glazer and Ereshefsky  were the first to conduct a pharmacoeconomic analysis on patients affected with so-called “revolving door” schizophrenia. The label was adopted to describe persons suffering from chronic disease with multiple relapses, frequent hospitalizations, and problems with adherence to prescribed medications. These patients have many problems and obstacles preventing them from living a normal life. They are also responsible for increased expenditures for healthcare, social services, and the justice system .
Antipsychotic drugs can help many revolving door patients to remain in a stable condition; however, a major problem for them is adherence to these prescribed drugs [1, 3]. The adherence of patients with schizophrenia is reduced over time. In fact, it has been demonstrated that partial adherence (i.e. missing 25-50% of doses) can reach 50% in 1 year and 75% in 2 years . An important advance in enhancing adherence has been the depot form of these drugs, also referred to as long-acting injectables (LAIs). They have become a mainstay in treatment because of their prolonged effect and consequent prevention of much of the intentional and non-intentional non-adherence that results in treatment failures and hospitalizations . The clinically meaningful superiority of depot medication compared to oral antipsychotic drugs in outpatients with schizophrenia has also been confirmed by the findings of a recent meta-analysis which demonstrated that depot formulations significantly reduced relapses from an average of 33.2% to 21.5% .
A further advance has been the development of atypical antipsychotics. They have advantages over the traditional drugs in that they improve both the positive and negative symptoms of the disease . A depot form of atypical antipsychotic was not available until 2002, the first of which was risperidone (RIS-LAI) [7, 8]. In a review of the clinical research, Möller concluded that RIS-LAI displayed clinical efficacy and a reasonable degree of tolerability . Moreover, based on the results of a recent multi-centre cohort study across 15 French regions that accounted for 77.6% of the French population in 2005, RIS-LAI use compared to all other LAIs and first or second generation per os antipsychotics was associated with a 34% reduced rate of hospitalization . A clinical disadvantage is that, although clinically effective, it must be administered every two weeks, usually by a specially trained psychiatric nurse or physician .
More recently, paliperidone palmitate (PP-LAI) has been developed and approved by the European Medicines Agency . Among the other advantages that it shares with existing drugs, this new product has an added advantage in that it may be administered monthly . PP-LAI is already marketed in several European markets, most often at a higher acquisition price than RIS-LAI.
Although the clinical use of PP-LAI has been investigated in a number of randomized controlled trials [13–17], few economic evaluations have yet been conducted. A search of the international peer reviewed literature revealed one study from the USA that included PP-LAI . However, that study did not use data inputs generated by PP-LAI, but rather they used data from RIS-LAI studies and assumed the two drugs to be exactly equal. Considering differences in dosing regimens, such assumptions and associated cost outcomes may not be valid. Several pharmacoeconomic studies have compared RIS-LAI with other drugs, mainly oral atypicals and traditional depots. In his review of those studies, Haycox found that RIS-LAI was the dominant strategy in all eight different countries, using different analytical models .
In Greece, a single pharmacoeconomic study by Geitona and associates  was published which focused on paliperidone extended release oral tablets. That study demonstrated that paliperidone was cost-effective over all other oral drugs tested, including risperidone, olanzapine, quetiapine, ziprasidone and aripiprazole. Paliperidone had the lowest overall cost and the highest number of days with stable disease. No other similar studies from Greece could be located.
Given that PP-LAI has a higher acquisition price than RIS-LAI and taking into consideration the scarcity of resources health care systems are faced with, economic evaluation of new technologies is important for decision making purposes. The aim of this paper is to compare costs and outcomes of PP-LAI versus RIS-LAI for the treatment of persons with chronic schizophrenia in Greece.