| Factor | Influence on adherence | Reference |
| Medication | ||
| Regimen | ↓ ↓ | Farmer 1999,21 Sacket 1976,36 Rand 2005,35 Rapoff 200616 |
| Lengthier and more complicated | ||
| Polypharmacy* | ||
| Duration | ↓ | |
| Long term | ||
| Type | ↓ | |
| Not have medication direct effect | ||
| Administration | ↓ | Garcia-Aymerich 2000,40 James 1985,38 Tashkin 199534 |
| Inhaler | ||
| Cost | ↓ | Hughes 2004,19 Soumerai 199143 |
| Inability to pay or reduce access | ||
| Adverse effects | ↓ | Col 199042 |
| Patient | ||
| Old age | ↑ | Rand 199528 |
| Comorbidity including anxiety and depression | ↓ | Cully 2006,46 Hughes 2004,19 Morris 199286 |
| Cognitive defect | ↓ | Incalzi 199744 |
| Difficulty reading | ↓ | Zuccollo 198545 |
| Perception of the disease | ↓ ↑ | DiMatteo,12 Rapoff 200616 |
| Lack of regular symptom | ||
| Affect daily activities and anticipate problem | ||
| Perception or social support | ↑ | Tashkin 199534 |
| Stable family life and caregiver | ||
| Health care provider | ||
| Type of physician | ↑ | Lau 199648 |
| Specialist | ||
| Type of care and service | ↑ ↑ | Tashkin 199534 |
| Continuity of care follow-up and written supervision | ||
| Written instruction | ||
| Self-management with positive reinforcement | ↑ | Turner 1995,15 Dunbar 197952 |
*Polypharmacy has not always proven to be associated with decreased adherence.
†Older age may be associated with greater number of comorbid conditions, cognitive defect and difficulty reading, which reduces adherence.