Table 3.

Evidence synthesis

Factor		Relationship
		Indication/therapy	Effect direction	Evidence for effect
Social and economic	Education	Parkinson disease	↑	O
		Chronic pain	?	O
		Hepatitis C	↑	O
		HIV	↓	–
		Oral anti-cancer agents	↑	O
			?	O
		Cardiovascular conditions	↑	+
			↓	O
			?	O
	Employed	Hepatitis C	↓	O
		Inflammatory arthritis	?	O
		HIV	↑	+
		Cardiovascular conditions	↑	O
			↓	O
			?	O
	Ethnic status	Hepatitis C	?	O
			Others > African American	O
		Inflammatory arthritis	White > others	+
		HIV	White > Black	+
		Oral anti-cancer agents	White > Black	O
			White > Asian	–
			White > Hispanic	–
			White > non-White	O
			African American > others	O
			Non-White > others	O
		Cardiovascular conditions	White > others	++
			Non-Asian > Asian	O
			Major ethnic groups > ethnic minorities	+
	Financial status/income	Parkinson disease	↑	O
		Hepatitis C	↓	O
		Chronic conditions	↑	+
		Oral anti-cancer agents	↑	+
		Cardiovascular conditions	↑	O
			?	O
	Socioeconomic status	Inflammatory arthritis	↓	O
		Oral anti-cancer agents	?	O
			↑	O
		Cardiovascular conditions	↑	+
	Married/not living alone	Parkinson disease	↑	O
		Inflammatory arthritis	↑	O
		Chronic conditions	?	O
		HIV	↓	O
		Oral anti-cancer agents	↓	O
			↑	O
			?	–
		Cardiovascular conditions	↑	O
			?	O
	Social support	Inflammatory arthritis	↑	O
		Oral anti-cancer agents	?	O
			↑	O
		Cardiovascular conditions	↑	O
			↕	O
Therapy related	Duration of therapy	Oral anti-cancer agents	↓	–
			?	O
			1 year > 3 or 5 years	–
			More than 2 years > 0–2 years	–
	Frequency of intake	Parkinson disease	↑	O
		Inflammatory arthritis	?	O
		Cardiovascular conditions	?	O
	Number of pills taken per day	Cardiovascular conditions	?	O
	Number of tablets	Oral anti-cancer agents	?	O
			2 > 1	O
	Different medications	Parkinson disease	↓	O
		Chronic pain	↓	O
			↑	O
		Inflammatory arthritis	↑	O
		Oral anti-cancer agents	↑	O
			↓	O
			?	O
		Cardiovascular conditions	↓	+
			?	O
	Taking medication at meals	Oral anti-cancer agents	↓	O
Disease related	Duration of disease	Chronic pain	?	O
		Hepatitis C	↑	O
		Inflammatory arthritis	↓	–
		Oral anti-cancer agents	↓	–
			↑	O
			?	–
		Cardiovascular conditions	↑	O
			↓	O
			?	–
Patient related	Age (years)	Parkinson disease	↑	+
		Chronic pain	↑	O
		Hepatitis C	?	O
		Inflammatory arthritis	↑	O
			55–64 > others	O
		Chronic conditions	↑	O
			↓	O
			65 and older > younger than 65	O
		HIV	18–40 < age more than 41	O
			Age less than 45 vs. more than 45	+
		Oral anti-cancer agents	Middle age > very old (≥ 75) > young (≤ 45)	+
			Middle age (41–60) > others	O
			Less than 45 < others	O
			Less than 46 or more than 85 > others	O
			↑
			↓	O
			?	O
				O
		Cardiovascular conditions	↓	O
			↑	+
			?	O
			≤ 55 < others	O
			≤ 55: NR	O
			> 60 > others	O
			35–56 > others
				O
	Comorbidity	Inflammatory arthritis	↑	O
		Oral anti-cancer agents	Charlson comorbidity index: ↑	O
			↓
				O
	Comorbidity (physical)	Hepatitis C	↓	O
			?	O
		Chronic conditions	↓	O
		Cardiovascular conditions	↓	O
			↑	O
			↕	O
	Comorbidity (mental)	Parkinson disease	↓	O
		Hepatitis C	↓	+
			↕	O
			↑	O
			?	O
		Chronic conditions	↓	O
		Cardiovascular conditions	↓	+
			↕	O
			?	O
	Comorbidity (depression)	Oral anti-cancer agents	↓	+
		HIV	↓	+
		Cardiovascular conditions	↓	++
	Gender (female)	Chronic pain	↑	O
		Hepatitis C	↓	O
			↑	O
			?	O
		Inflammatory arthritis	↓	O
			↑	O
		Chronic conditions	↓	O
			?	O
		Oral anti-cancer agents	↓	O
			↑	O
			?	O
		Cardiovascular conditions	↑	+
			?	O
			↓	O
Health care system related	Co-payments	Inflammatory arthritis	↓	+
		Chronic conditions	↓	+
			↑	–
		Not restricted	↓	++
		Oral anti-cancer agents	Less than US$10 > more than US$10	O
			↑	O
			↓	O
		Cardiovascular conditions	↓	+
			No > yes	+
			Yes > no	O
			US$0 > US$1 to US$9	+
			US$0 > US$10 to US$29	+
	Medication costs	Inflammatory arthritis	↓	O
		Oral anti-cancer agents	↓	O
	Health insurance	Chronic conditions	↑	O
		Cardiovascular conditions	↑	O
			?	O

Effect direction. ↑ positive effect on adherence, ↓ negative effect on adherence, ↕ inconsistent effect direction, ? effect direction not or unclearly reported, ++ robust evidence for an impact, + some evidence for an impact, − probably no impact, O uncertain impact