According to the Global Burden of Disease Study (GBD) 2019, mental disorders remain one of the top 10 leading causes of disease burden worldwide. In the study using these results to report trends in the burden of diseases, injuries, and risk factors, depression, bipolar disorder, and schizophrenia were among the top 25 in the Years Lived with Disability (YLDs) ranking [1]. This shows that these major mental disorders cause a significant burden, and medication plays an important role in their treatment as it affects the prognosis and course of these diseases [2]. Therefore, medication adherence, which is defined as “the degree to which the patient acts according to the prescribed set interval and dosage of the drug,” [3] is an essential issue. However patients with mental disorders tend to avoid taking drugs compared to other patients with physical disorders [4]. As poor adherence may lead to disease recurrence, repeated and long-term hospitalization, loss of productivity, increased mortality, extended treatment period, and national economic losses, drug compliance is an important issue from both the quality of life and health economics perspectives [5].

Numerous studies have identified a variety of factors that influence medication adherence in psychiatric patients [6] as well as factors associated with adherence/nonadherence within specific disease groups. In the study of patients with schizophrenia, negative attitudes or subjective response to medication, previous nonadherence, and poor therapeutic alliance were associated with nonadherence [7]. Drug side effects were most commonly reported reason for treatment discontinuation in patients with depression [8,9] and other motivating factors for adherence included trust in medical staff, one’s will to treat disease, convenience in taking the drug formulation (method, frequency, simplicity of operation, etc.), and the appearance of the drug (perceptual aspects such as size, number, color, etc.) [8]. In patients with bipolar disorder, poor drug adherence was associated with considerably higher risks of relapse, recurrence, hospitalization, and suicide attempts, as well as lower chances of achieving remission and recovery [10,11]. Also side effects, complicated drug regimens, unfavorable attitudes toward medicine, lack of insight, and poor therapeutic relationships were contributing factors [9].

From these results, we can suspect that the factors affecting adherence reflect patients’ expectations, attitudes, and values about medication and that there are some differences between disease groups. It is now more important than ever to understand what patients’ value because of the recent rise of patientcentered care, where treatment decision-makings are made by everyone, not just doctors. Also, if people with different psychiatric disorders differ in the degree to which they value certain values related to adherence, then incorporating these factors into treatment may increase adherence and potentially lead to better treatment outcomes. However, few studies have compared differences between disease groups, and multicenter studies are even rarer.

Therefore, we conducted a multicenter survey-based study which was designed to examine the expectations for medication among patients who were diagnosed with depressive disorder, bipolar disorder, or psychotic disorder and the results will help us understand their expectations and preferences for medication and determine if there are differences between conditions.

This was the first multicentered survey-based study to examine expectations and preferences for medication of patients with depressive disorder, bipolar disorder, or psychotic disorder in Korea. The result of our survey showed that in the total population, patients with major psychiatric illnesses considered high efficacy as the main wish for medication, themselves and a doctor as the main treatment decision makers, and tablet/capsule as the preferred formulation. The preference ratio of high efficacy in the depressive group was significantly lower and the ratio of less amount was significantly higher compared to the psychotic and bipolar groups. Preference ratio of a doctor as the important treatment decision maker in the bipolar group was higher compared to the other disorder groups. Psychotic group had a higher preference rate for extended release drugs compared to other two groups in preferred drug type category. The significant differences between the disorders confirms the importance of this survey in identifying patients’ preferences and values for medication and incorporating them into treatment.

In studies of factors affecting medication adherence, efficacy and side effects are considered to be tied for importance, and in this study, high efficacy was the most desired value by patients, followed by low side effects. The rate of valuing the high effects of drugs was significantly higher in the psychotic disorders and bipolar disorders groups than that in the depression group. According to Achtyes et al. [13], patients with schizophrenia spectrum disorders rated efficacy as the most important factor for using a drug. In the study which explored the views of patients, caregivers, and experts on factors influencing medication adherence in patients with schizophrenia; both patients and caregivers rated efficacy as the most important factor, and prioritized side effects relatively lower over positive drug aspects [14]. Similarly, in a study of depressed type I bipolar patient, the most commonly expressed expectations were a reduction in symptoms and a balanced mood [10]. This shows similar results to our study.

Relatively, compared to the other groups, depressed patients were less likely to value efficacy and significantly more likely to favor fewer pills. Studies have shown that other factors may be more important than simply efficacy in influencing medication adherence in depressed patients [11]. The results of a study by Srimongkon et al. [15], which investigated consumer-related factors that affect antidepressant adherence, treatment efficacy, beliefs, and perceptions about antidepressants, were major influencing factors during the implementation phase of adherence. This study also showed that most participants were motivated to remain adherent when the benefits of the medication outweighed the harm; however, if the negative factors far outweighed the positive factors, patients would consider discontinuing treatment. According to a study by Eisen et al. [16], compliance improved dramatically as the frequency of drug administration decreased. In a study on treatment compliance of antidepressants, Demyttenaere [17] reported that monotherapy generally results in better compliance than polypharmacy and suggested that for antidepressants, a one-day regimen and drugs with a longer half-life are preferable.

Taken together, efficacy and side effects are the main factors that patients value the most from medication, and especially in depressed patients, considering the number of pills or other factors that patients view as positive or negative and applying them to treatment may lead to better outcomes.

As for the main treatment decision making, patients’ opinions were found to be the most important in the overall group with doctors’ opinions almost as important. This is consistent with the finding of other study that patients with mental illness have a desire to be involved in medication and hospitalization decisions and have a higher preference for participation in decision-making compared to patients with general physical illness [18].

However, in the bipolar disorders group, the proportion of doctors’ opinions being important was higher than that of patients. In a study by De Las Cuevas et al. [19] that evaluated the extent to which psychiatric patients’ treatment adherence was affected by the concordance between preferred and actual participation in decision-making, most psychiatric outpatients preferred a collaborative role in decision-making. Self-reported adherence was significantly higher in patients in whom there was concordance between their preferences and their experiences of participation in decision-making, regardless of the type of participation preferred. In a study by Lazary et al. [20] comparing six self-reported variables related to medication adherence in patients with schizophrenia, bipolar disorder, and depression, high doctor locus of control was significantly associated with increased treatment adherence only in the bipolar disorder group, suggesting that the patient-psychiatrist relationship may be particularly relevant to medication adherence in patients with bipolar disorder.

Tablets/capsules were the most preferred formulation in the overall population and were the same within disease groups, likely because they are the most commonly used form. Injectables were the least preferred formulation in the overall population. In a study of schizophrenia patients’ preferences for long-acting injectables and oral antipsychotics by Blackwood et al. [21], the most common reasons cited by patients who preferred pills to injectables were “feeling less embarrassed ”(46%) and “feeling less pain”(18%). Lee et al. [22] found that patients who preferred oral medications to long-acting injectables (LAIs) cited “disliking injections” (32.4%) and “thinking oral medications were sufficient” (43.4%) as reasons for not using LAIs. While these results may explain the low preference for injection, it is possible that the patient’s disease itself had a significant impact on the preference survey, as the “injection” as a treatment formula may be unfamiliar to certain patients for which LAIs are underutilized, which would be a limitation of our study.

This study had several limitations. Firstly, the participants in this study did not include patients from primary care, the results may not represent the entire patient group. Additionally, the survey results may have been influenced by a selection bias since only individuals who voluntarily participated were included. This could potentially introduce a bias towards patients who were more cooperative or had more favorable attitudes towards their doctors and treatment. Moreover, it was challenging to ascertain the characteristics of the patients who refused to participate. Furthermore, the inclusion of certain medication formulations (e.g., injections) as options in a survey about preferred drug types may have biased the results, particularly in patient populations where these formulations are not commonly used. It is important to note that the survey did not utilize a standard questionnaire. Although the constant sum scale method employed in the survey was effective in determining the relative importance of different factors, it may have posed difficulties for patients who have difficulty matching the sum of 100. Lastly, the observed significant differences between disease groups could be attributed to inherent differences in the diseases themselves, introducing a bias in the study. Nevertheless, this study is meaningful in that it is the first multicenter survey-study to identify the expectation for medication, main treatment decision-makers, and preferred drug types in patients with three disorder groups—psychotic disorders, bipolar disorder, and depressive disorder. Our study is particularly significant as the recent rise of personalized medicine and patient-centered care is changing the once one-sided patient-physician relationship to a mutually collaborative way.

Still, there is often disagreement about whether shared decision-making can help improve adherence and treatment effectiveness by ensuring that care reflects patients’ expectations, values, and preferences for care. However, in many cases, their reduced capacity can be compensated for by more intensive educational interventions [23]. If the patient’s preference is matched to the treatment modality, the patient’s satisfaction and treatment adherence will increase, thereby improving treatment participation and consequently alleviating symptoms. Recognizing that patients have a desire to participate in the treatment decision-making process, identifying the most expected elements of medication, the level of shared decision-making participation, and the patient’s preferences for medication formulations, and providing healthcare services accordingly will improve adherence to treatment and lead to better treatment outcomes.