Table 1.
Summary of findings on potential positive and negative factors influencing adherence rates.
| Author [year] | Study design | Patient population | Key potential negative factors | Key potential positive factors |
|---|---|---|---|---|
| Acosta et al. [2009] | Prospective | Schizophrenia, N=74 | Poor insight (p = 0.04), higher scores for conceptual disorganization in the PANSS items (p = 0.068) | NR |
| Ascher-Svanumet al. [2006] | Prospective | Schizophrenia, N = 1,579 | Prior poor adherence (p < 0.001), prior illicit drug use (p = 0.025), prior alcohol use (p = 0.015), prior treatment with antidepressants, and greater patient-reported, medication-related cognitive impairment (p < 0.001) | NR |
| Hudson et al. [2004] | Prospective | Schizophrenia, N = 153 | Barriers including stigma of taking medications, adverse drug reactions, forgetfulness, lack of social support (significance level NR), higher PANSS total score (p = 0.05), lower education level (p = 0.02), substance abuse (p = 0.01) | NR |
| Janssen et al. [2006] | Prospective | Schizophrenia, n = 500 (74.6%) Schizoaffective disorder, n = 110 (16.4%) Other, n = 60 (9.0%) |
Involuntary admission (p < 0.005), history of aggressive behaviour (p < 0.005), no school graduation (p < 0.005), substance disorder comorbidity (p < 0.005), not having competitive work (p < 0.005) | Switching to atypical antipsychotics (p < 0.001) |
| Linden et al. [2001] | Prospective | Schizophrenia, N = 122 | Physician’s judgment on lack of willingness of the patient to cooperate (p < 0.001), idiosyncratic assumptions (p < 0.05) | Older age (p < 0.05), longer duration of illness (p < 0.01), trust in the effectiveness of medication (significance NR), less tendency to feel responsible for their illness (significance NR) |
| Loffler et al. [2003] | Prospective | Schizophrenia, N = 307 | Subjective reasons for noncompliance include: side effects (50%), lack of acceptance of the necessity of pharmacological treatment (40%), lack of insight (27%) | Subjective reasons for compliance include: relapse prevention (88%), perceived benefit from medication (79%), positive relationship with a therapist (41%) |
| Novick et al. [2010] | Prospective | Schizophrenia, N = 6,731 | Alcohol dependence (p = 0.013) or substance abuse (p = 0.043) in a previous month, hospitalization in the last 6 months (p < 0.001) | Good prior adherence (p < 0.001), greater social activities (p < 0.001) |
| Aldebot and de Mamani [2009] | Cross-sectional (interview) | Schizophrenia/schizoaffective, N = 40 | Denial coping (p = 0.008) | NR |
| Borras et al. [2007] | Cross-sectional (interview) | Schizophrenia/other nonaffective disorders, N = 103 | Negatively influenced by spiritual belief (26%) | Positively influenced by spiritual belief (31%) |
| McCann et al. [2009] | Cross-sectional (interview) | Schizophrenia, N = 81 | Adverse events not associated with medication omission | |
| Olfson et al. [2006] | Cross-sectional (Postal survey) | 534 psychiatrists responded to the survey | Lack of awareness of mental illness (p = 0.021) | NR |
| Rettenbacher et al. [2004] | Cross-sectional (interview) | Schizophrenia, N = 61 | NR | Subjectively experienced positive effect on illness (p = 0.093) and everyday life (p = 0.072), psychiatrist inquiring medication intake (p = 0.074), more negative symptoms (p = 0.044), psychological side effects (p = 0.004) |
| Weiden et al. [2004] | Cross-sectional (postal survey) | Schizophrenia, N = 304 | Obesity (OR = 2.5; 95% CI 1.1–5.5) and subjective distress from weight gain (significance level NR) | NR |
| Valenstein et al. [2004] | Retrospective database analysis | Schizophrenia or schizoaffective disorder, N = 63,214 | Ethnicity (African-American) (OR 2.38; 95% CI 2.28–2.49), younger age < 45 (OR 1.31; 95% CI 1.25–1.37) | Atypical agent (clozapine) (p < 0.0001), switching from conventional to atypical therapy (p < 0.001) |
| Velligan et al. [2009] | Qualitative review and survey of experts | The survey involved 48 leading experts on adherence problems | Rating by experts on scale from 1 to 10: poor insight (7.2), distress associated with side effects (7.2), lack of/partial efficacy with continued symptoms (6.9), belief that the medications are no longer needed (6.7), ongoing substance use problems (6.6) | Results from literature review on positive factors include: positive therapeutic relationship, family and social support |
95% CI, 95% confidence interval; NR, not reported; OR, odds ratio; PANSS, Positive and Negative Syndrome Scale.