Medication Appropriateness, Polypharmacy, and Drug-Drug Interactions in Ambulatory Elderly Patients with Cardiovascular Diseases at Tikur Anbessa Specialized Hospital, Ethiopia

Figures & data

Table 1 Demographic and Clinical Characteristics of the Study Participants (N=384)

Variables	Description	Frequency (%)
Gender	Male	182 (47.4)
	Female	202 (52.6)
Age (years)	60–74 (young-old)	317 (82.6)
	75–83 (middle old)	59 (15.4)
	≥ 84 (oldest-old)	8 (2.1)
	Mean age ±SD	68.09 ±6.5
Presence of comorbidity	Yes	361 (93.7)
Number of comorbidities	< 5	364 (94.8)
	≥ 5	20 (4.2)
CCI	< 5	163 (42.4)
	≥ 5	221 (57.6)
Duration of the disease	< 5 yrs	159 (41.2)
	≥ 5 yrs	225 (58.6)

Abbreviations: CCI, Charlson comorbidity index; SD, standard deviation.

Table 2 The Most Frequent CVD Medications Prescribed Among Study Participants

	Top Ten Medications	Frequency (%)
1	Atorvastatin	250 (65)
2	Enalapril	225 (58.6)
3	Aspirin	180 (46.9)
4	Furosemide	170 (44.3)
5	Amlodipine	143 (37.2)
6	Metoprolol	119 (31.6)
7	Spironolactone	79 (20.6)
8	Hydrochlorothiazide	63 (16.4)
9	Warfarin	43 (11.2)
10	Digoxin	23 (6)

Figure 1 Inappropriate drug classes based on the AGS Beers criteria.

Table 3 Distribution of Inappropriate Prescriptions Using MAI Criteria

	MAI Criteria	Sum (Range)	Mean (SD)
1	Is there an indication for the drug?	703 (0–12)	1.83 ±2.5
2	Is the medication effective for the condition?	2285 (0–24)	6 ±3.6
3	Is the dosage correct?	1215 (0–10)	3.2 ±2.2
4	Are the directions correct?	491 (0–6)	1.3 ±1.3
5	Are there clinically significant drug-drug interactions	408 (1–16)	1.1 ±2.0
6	Are there clinically significant drug-disease/condition interactions?	635 (0–10)	1.7 ±1.65
7	Are the directions practical?	415 (0–5)	1.1 ±0.9
8	Is there unnecessary duplication with another drug (s)?	732 (0–7)	2 ± 1.3
9	Is the duration of therapy acceptable?	111 (0–3)	0.3 ±0.6
	The average weight of MAI	Frequency (%)
	0–30 points	324 (84.4%)
	31–60 points	57 (14.8%)
	61 and above points	3 (0.8%)

Table 4 Polypharmacy and Drug-Drug Interaction in the Study Participants

Variables		Frequency (%)
Number of drugs prescribed	1–4 medications	180 (46.9)
	≥ 5 medications	204 (53.1)
Presence of drug-drug interaction	Yes	346 (90.1)
Type of drug-drug interaction	Severe	58 (15.1)
	Moderate	288 (75)
	Mild	320 (83.3)

Table 5 List of Severe DDI, Their Prevalence, and Expected Negative Effects

List of Severe DDI	Prevalence of the DDI	Clinical Presentation
Enalapril and spironolactone	46 (73%)	Hyperkalemia
Amlodipine and carbamazepine	7 (11.1%)	Significantly reduce the blood levels of amlodipine
Enalapril and allopurinol	2 (3.2%)	Increased hypersensitivity to allopurinol
Amiodarone and furosemide	1 (1.6%)	Increase the risk of an irregular heart rhythm that may be serious.
Amiodarone and verapamil	1 (1.6%)	The additive effect, blood pressure may need to be checked more frequently
Amiodarone and warfarin	1 (1.6%)	Cause bleed more easily
Aspirin and rivaroxaban	1 (1.6%)	Increase the risk of bleeding, including severe and sometimes fatal hemorrhage.
Candesartan and spironolactone	1 (1.6%)	Increase potassium level in the blood.
Clopidogrel and omeprazole	1 (1.6%)	Reduce the effectiveness of clopidogrel in preventing heart attack or stroke.
Enalapril and losartan	1 (1.6%)	Increase the risk of side effects such as low blood pressure, kidney function impairment, and hyperkalemia
Verapamil and metoprolol	1 (1.6%)	Bradycardia or complete AV block

Abbreviation: AV, atrioventricular.

Table 6 Factors Associated with Inappropriate Medication Use

Variables	Description	COR (95% CI)	P-value	AOR (95% CI)	P-value
Age	Young old	1	0.27	1	0.53
	Middle old	0.613 (0.317,1.186)	0.152	0.362 (0.373,1.734)	0.761
	Oldest-old	1.302 (0.305,5.555)	0.721	3.873 (0.390,12.143)	0.234
Gender	Male	1	1	1	1
	Female	0.602 (0.814,2.414)	0.583
Presence of comorbidity	No	1	1	1	1
	Yes	5.587 (1.985,11.734)	0.004	0.425 (0.296,1.594)	0.066
CCI	<5	1	1	1	1
	≥ 5	0.437 (0.280,0.681)	0.00	0.694 (0.411,1.174)	0.154
Number of comorbidities	<	1876 (0.283,3.281)	0.012	1.340 (0.642,2.785)	0.745
	≥ 5	1	1	1	1
Number of medications	< 5 medications	1	1	1	1
	≥ 5 medications	0.123 (0.14,0.3)	0.00	5.1 (0.110,0.386)	0.00

Note: P=0.00 is when p <0.0001.

Abbreviation: CCI, Charlson comorbidity index.