The present study included a long observation period (52 weeks) and a large sample of Chinese patients with schizophrenia. A total of 430 patients with first-episode schizophrenia were recruited from six hospitals in China and were administered antipsychotic drugs. Of the 430 patients with schizophrenia, 96 patients reported DAI-10 scores at all 7 time points investigated, while 104 patients discontinued the study during the 1-year follow-up. Attitudes toward antipsychotic drugs at the beginning of the treatment (even before the treatment) were an important predictor of discontinuation during the treatment. At baseline, female sex and a DAI-10 total score greater than − 1 were independent protective factors against discontinuation of antipsychotic drug treatments during the 1-year follow-up. At baseline, the severity of the disease (CGI-s) and insight were shown to have an influence on baseline DAI-10 total scores.

In the present study, subjective attitudes toward drug compliance changed during the one-year follow-up treatment; however, only the baseline attitude was shown to be associated with discontinuation. This finding is supported by previous studies [6, 11]. Both Brain, Allerby [11] and Gaebel, Riesbeck [6] found that the baseline DAI score predicted medication continuation in a one-year follow-up study. In particular, consistent with the present study, Gaebel, Riesbeck [6] also examined first-episode schizophrenia patients.

Herein, baseline DAI scores were evaluated before starting continuous antipsychotic treatment. However, these scores could still predict medication adherence. A possible explanation may be that attitudes toward drugs among patients with schizophrenia have been reported to be associated with multiple factors, not only the experience with medications. Possible factors associated with attitudes toward drugs among patients with schizophrenia included self-stigmatization [25], duration of treatment [7, 26], duration of illness [27, 28], PANSS scores [13, 28], insight regarding illness [29], and illness severity [28]. In this study, baseline CGI-s and PANSS-G12 (insight) scores were associated with baseline DAI-10 total scores, indicating that the characteristics of the disease may influence attitudes toward drugs. Notably, it was reported that stigmatizing attitudes toward people with mental illness and psychosis are much stronger in Chinese culture than in European or American cultures [30, 31]. The cultural influences may shape the psychological factors aggravating insight deficits in schizophrenia, contributing to the association of insight with attitudes toward drugs in Chinese patients with schizophrenia.

Another possible explanation may be that factors related to the effects or feelings of drug treatment do not influence drug compliance via attitudes toward drug compliance. This is supported by findings from Robles Garcia and Salazar Alvarado [32], who reported that side effects during antipsychotic drug treatment were not biased to either adherent or nonadherent patients. Kuroda, Sun [19] compared attitudes toward medication and related factors for patients with schizophrenia in Japan and China. Although Patients in Tokyo had the higher proportion of antipsychotics polypharmacy and more complicated drug regimens, they did not have more negative attitudes toward medication than patients in Beijing. In particular, Kuroda, Sun [19] found that the side effects of medication were not associated with attitudes toward medication in patients with schizophrenia in China. Attitudes toward drug compliance may be more closely related to previous symptoms or experience. Kako, Ito [14] found that DAI-30 scores were correlated with past awareness and attribution subscale scores but not correlated with current awareness and attribution subscale scores. These findings indicated that attitudes toward medications may derive from patients’ subjective interpretation of their previous medicated state, thus affecting whether they continue the drug treatment [8, 32]. Although our sample comprised first-episode schizophrenia patients, the patients could also have previous experience related to schizophrenia (including suffering mental diseases, receiving some treatment, visiting the healthcare system or related descriptions from others) that impacted their attitudes toward drugs.

Additionally, medication adherence consists of a series of interrelated steps, including patients, their health providers and healthcare systems [33]. Subjective attitudes toward drug compliance may also be influenced by health providers, demographic factors (i.e., age [27] and sex [34]) and cultural factors [35]. Notably, compared to only 40% patients with schizophrenia living with their families in the United States, over 90% of Chinese patients with schizophrenia did so [36], leading to the tightly knit interdependence between patients and families. Thus, family-related factors (such as family caregivers’ affiliate stigma, knowledge related to schizophrenia, and income) were also found to influence schizophrenia patients’ attitudes toward drugs and treatment [37]. These factors may have an impact on attitudes toward drugs before formal drug treatment and can be difficult to change during the following treatment, thus leading to adherence or nonadherence during the treatment. Our study was conducted in China, and the findings suggest that researchers should focus on initial attitudes toward drugs among patients with schizophrenia in Chinese community settings.

In the present study, the cutoff value was suggested to be -1 based on the ROC analysis. This cutoff value was lower than that reported by Brain, Allerby [11]. A possible reason for the discrepancy may be that the patients recruited by Brain, Allerby [11] were not first-episode patients, and they had a longer duration of illness. Duration of illness and previous experiences with medication treatment have been shown to be associated with attitudes toward drugs [7, 13], thus potentially explaining the discrepancy between the previous study and the present study.

Previous studies reported that male patients with schizophrenia had more negative attitudes toward antipsychotic drugs than females with schizophrenia in both Western [38] and Chinese samples [34]. Our study did not find that sex was associated with baseline attitudes toward drugs. However, the present study indicated that males with schizophrenia had a higher risk of treatment discontinuation than females. This may be because our samples comprised first-episode drug-naïve patients. Gender differences may influence discontinuation via factors related to the following treatments. For example, females were more likely to seek help from others and more likely to have stronger and longer-lasting relationships with their families [38]. Furthermore, females may focus more on internalized feelings, which may lead to benefits from psychoeducation during treatment [39]. Additionally, in a Chinese study, female outpatients with schizophrenia (taking antipsychotic medication continuously for at least one month) were found to be related better attitudes toward drugs [19]. The above evidence supports that gender differences may influence adherence during subsequent treatment. Comparatively, before drug treatment (at baseline), gender differences may not have an impact on attitudes toward drugs in the present study. The severity of symptoms and insight into the illness, on the other hand, have an impact on attitudes toward medication in schizophrenia before treatment.

Our study suggests that baseline attitudes toward antipsychotic medication should be further investigated in order to improve adherence among patients with schizophrenia in clinical settings. Baseline attitudes toward drugs can be measured easily using the DAI-10; individuals with DAI-10 total scores less than − 1 may be more likely to discontinue treatment. Additionally, male sex, more severe symptoms and insight into the illness are potential direct or indirect risk factors for treatment discontinuation. Interventions or psychoeducation for improving adherence to antipsychotic treatment should focus on patients with these risk factors.

One limitation of our study is that we did not examine additional sociodemographic variables (e.g., marital status, income, and living area). These factors may also influence attitudes toward drugs. Another limitation of our study was the lack of data on psychotherapy or psychoeducation interventions at baseline or during treatment in the present study. Previous studies have reported that these interventions may improve medication adherence of schizophrenia patients [40] and reduce transition to psychosis in early stages of schizophrenia [41].Thus, psychotherapy or psychoeducation interventions at baseline or during treatment may have potential effect upon attitudes toward drugs. These limitations will be noted and improved upon in future studies.