Prevalence, Incidence, and Characteristics of Adverse Drug Reactions Among Older Adults Hospitalized at Mbarara Regional Referral Hospital, Uganda: A Prospective Cohort Study

Figures & data

Figure 1 Study recruitment process of hospitalized older patients at MRRH, Uganda.

Table 1 Patient Characteristics of Older Adults 60 Years and Above Admitted at MRRH, Southwestern Uganda from November 2020 to May 2021

Variables	Categories	Frequency (%) (N=523)
Gender	Female	254 (48.6)
	Male	269 (51.4)
Age in years; median (IQR)=67 (62–76)	60–75	356 (68.1)
	≥75	167 (31.9)
Ward	Medical	262 (50.1)
	Surgery	163 (31.2)
	Oncology	98 (18.7)
Type of admission	Not Emergency	197 (37.7)
	Emergency	326 (62.3)
Medication use in previous 3 months	No	49 (9.4)
	Yes	474 (90.6)
Use of an herbal drug in previous 4 weeks	No	251 (48.0)
	Yes	272 (52.0)
Comorbidity	No	185 (35.4)
	Yes	338 (64.6)
Length of Hospital stay (days) Median (IQR): 8 (4–12)	≤5	180 (34.4)
	5–10	186 (35.6)
	≥11	157 (30.0)

Abbreviation: IQR, interquartile range.

Figure 2 Documented medical, surgical, and oncologic conditions among older adults 60 years and above admitted at MRRH, southwestern Uganda from November 2020 to May 2021.

Figure 3 Medications used by older adults 60 years and above admitted at MRRH, Southwestern Uganda from November 2020 to May 2021.

Table 2 The Incidence of Adverse Drug Reactions Among Older Adults 60 Years and Above Admitted at MRRH, Southwestern Uganda from November 2020 to May 2021

S.No.	Parameter	Frequency
1	Total number of ADR incidents	365 ADRs
2	Total person-days	4702 person-days
3	ADRs/person-day×1000	78 ADRs/1000 person-days
4	ADRs/admission	0.7 ADRs/admission

Figure 4 The prevalence of adverse drug reactions among older adults 60 years and above admitted at MRRH, southwestern Uganda from November 2020 to May 2021.

Table 3 The Categories of ADRs Detected Among Older Adults 60 Years and Above Admitted at MRRH, Southwestern Uganda from November 2020 to May 2021

Category of ADR	Frequency (%)	Frequencies of Specific ADRs Detected (N=365)
Gastrointestinal	148 (40.6)	Constipation (42), Nausea (38), Nausea and vomiting (36), Abdominal pain (10), Anorexia (7), Dyspepsia (3), Flatulence (3), Gastric irritation (3), Stomatitis (2), Dysgeusia (2), Diarrhea (2)
Central nervous system	75 (20.5)	Dizziness (29), Drowsiness (16), Headache (10), Malaise (4), Vertigo (5), Insomnia (4), Confusion (2), CNS depression (1), Lethargy (1), CNS toxicity (1), Depression (1), Seizure (1)
Cardiovascular	32 (8.8)	Hypotension (16), Hypertension (5), Arrhythmia (5), Edema (4), Palpitation (1), Syncope (1)
Endocrine & metabolic	31 (8.5)	Hypoglycemia (13), Hyponatremia (4), Hyperglycemia (4), Hypokalemia (6), Hyperkalemia (2), Increased thirst (1), Hypernatremia (1)
Dermatologic	18 (4.9)	Diaphoresis (7), Skin rash (5), Pruritus (5), Urticaria (1)
Peripheral nervous system	11 (3.1)	Extrapyramidal reaction (4), Paresthesia (3), Peripheral neuropathy (2), Restlessness (1), Rigors (1)
Neuromuscular & skeletal	13 (3.6)	Asthenia (9), Muscle spasm (2), Fatigue (1), Back pain (1)
Otic	6 (1.6)	Tinnitus (3), Hearing loss (3)
Miscellaneous	6 (1.6)	Fever (6)
Local	6 (1.6)	Induration at the injection site (4), Skin tightness (2)
Hypersensitivity	5 (1.4)	Hypersensitivity reaction (4), Angioedema (1)
Renal	4 (1.1)	Renal failure (4)
Genitourinary	3 (0.8)	Vaginitis (1), Dysuria (1), Vaginal candidiasis (1)
Hematologic & oncologic	3 (0.8)	Bleeding (2), Leukopenia (1)
Respiratory	3 (0.8)	Bronchospasm (2), Cough (1)
Hepatic	1 (0.3)	Hepatitis (1)

Abbreviation: CNS, central nervous system.

Table 4 The Characteristics of the Detected ADRs Among Older Adults 60 Years and Above Admitted at MRRH, Southwestern Uganda from November 2020 to May 2021

Variables	Category	Frequency	Percentage (N=365)
Mechanism of ADR	Type A (Dose-dependent reactions)	305	83.6
	Type B (Bizarre reactions)	46	12.6
	Type C (Chronic reactions)	6	1.6
	Type E (Withdrawal reactions)	5	1.4
	Type F (Failure of therapy)	3	0.8
Severity of ADR	Mild	237	64.9
	Moderate	118	32.3
	Severe	10	2.8
Preventability of ADR
Non-preventable		200	54.8
Definitely preventable	There was a previous ADR or allergy to the drug	47	43.9^a
	The drug involved was inappropriate to the patient	39	36.5^a
	Inappropriate dose, route or frequency given	21	19.6^a
	Total	107	29.3
Probably preventable 58 (15.9%)	Monitoring tests were not performed	22	37.9^b
	Drug interaction was involved in ADR	17	29.3^b
	Preventive measures not given	19	32.8^b
	Total	58	15.9

Notes:^aThe denominator is 107. ^bThe denominator is 58.

Table 5 The Drugs Implicated in the Identified ADRs and the Associated Specific ADRs Among Hospitalized Older Adults, MRRH, Uganda

ATC Classes of the Drugs Used (Frequency, %)	Specific Drugs (Associated ADRs) N=365 ADRs
C: Cardiovascular system drugs (76, 20.8)	Furosemide (n=38: Dizziness (5), Hyponatremia (5), Hypotension (5), Hypokalemia (4), Vertigo (4), Constipation (3), Muscle spasm (2), Asthenia (2), Hearing loss (2), Drowsiness (1), Restlessness (1), Gastric irritation (1), Nausea (1), Headache (1); Fever (1)); Digoxin (n=7: Arrhythmia (3), Dizziness (2), Asthenia (1), Abdominal pain (1)); Spironolactone (n=4: Nausea (2), Hyperkalemia (2)); Nifedipine (n=4: Dizziness (1), Headache (1), Asthenia (1), Constipation (1)); Carvedilol (n=3: Syncope (1), Hypotension (1), Fatigue (1)); Enalapril (n=3: Hypotension (2), Renal failure (1)); Bisoprolol (n=2: Arrhythmia (1), Hypotension (1)); Methyldopa (n=2: Flatulence (1), Hypertension (1)); ISD (n=2: Hypotension (2)); Captopril (n=2: Cough (1), Renal failure (1)); Amlodipine (n=1: Hypotension), Atenolol (n=1: Arrhythmia); Atorvastatin (n=1: Malaise); Diltiazem (n=1: Asthenia); Losartan (n=1: Hypotension); Nifedipine and Losartan (n=1: Hypotension); Tolvaptan (n=1: Increased thirst); Digoxin and Furosemide (n=1: Dizziness); Hydrochlorothiazide (n=1: Hyperglycemia)
N: Nervous system agents (75, 20.5)	Tramadol (n=38: Constipation (25), Diaphoresis (4), Nausea (2), Nausea and vomiting (2), Insomnia (2), Drowsiness (1), Tinnitus (1), Seizure (1)); Morphine (n=16: Constipation (7), Drowsiness (4), Dizziness (2), Hypotension (2), Insomnia (1)); Diclofenac (n=7: Dyspepsia (3), Constipation (2), Heart burn (1), Pruritus (1)); Phenytoin (n=5: Dizziness (1), Drowsiness (2), Edema (2)); Chlorpromazine (n=2: Extrapyramidal reaction (1), Constipation (1)); Chlorpromazine and Haloperidol (n=2: Extrapyramidal reaction (2)); Haloperidol (n=1: Lethargy); Paracetamol (n=1: Skin rash); Risperidone (n=1: Extrapyramidal reaction); Pethidine (n=1: Constipation); Diazepam (n=1: CNS depression)
J: Anti-infective for systemic use (71, 19.4)	Ceftriaxone (n=51: Dizziness (15), Nausea (14), Nausea and vomiting (5), Induration at injection site (3), Diaphoresis (2), Headache (2), Skin rash (2), Pruritus (2), Skin tightness (2), Dysgeusia (1), Fever (1), Drowsiness (1), Flatulence (1)); Ciprofloxacin (n=5: Nausea (3), Constipation (1), Bronchospasm (1)); Dolutegravir (n=3: Hyperglycemia (2), Depression (1)); Isoniazid (n=2: Peripheral neuropathy (1), Hepatitis (1)); Fluconazole (n=2: Nausea and vomiting (1), Abdominal pain (1)); Clarithromycin (n=1: Abdominal pain); Efavirenz (n=1: CNS toxicity); Piperacillin and tazobactam (n=1: Rigors); Co-trimoxazole (n=1: Abdominal pain); Azithromycin (n=1: Abdominal pain); Clindamycin (n=1: Pruritus); Cloxacillin (n=1: Urticaria); Amoxicillin clavulanate (n=1: Nausea)
L: Antineoplastic and immunomodulating agents (69, 18.9)	Docetaxel (n=12: Nausea and vomiting (7), Edema (2), Anorexia (2), Nausea (1)); Capecitabine (n=6: Anorexia (3), Paresthesia (2), Stomatitis (1)); Cisplatin and Fluorouracil (n=5: Nausea and vomiting (5)); Doxorubicin (n=5: Nausea and vomiting (3), Asthenia (2)); Epirubicin and Cisplatin (n=4: Nausea (1), Nausea and vomiting (3)); Cisplatin (n=4: Tinnitus (2), Nausea and vomiting (1), Renal failure (1)); Fluorouracil (n=4: Confusion (1), Anorexia (1), Nausea (1), Stomatitis (1)); Rituximab (n=3: Asthenia (2), Pruritus (1)); Dacarbazine (n=3: Nausea (1), Paresthesia (1), Anorexia (1)); Paclitaxel (n=3: Peripheral neuropathy (1), Nausea (1), Hypersensitivity reaction (1)); Erlotinib (n=2: Skin rash (2)); Goserelin (n=2: Headache (1), Diaphoresis (1)), Epirubicin (n=2: Hypersensitivity reaction (2)); Vincristine and Rituximab (n=2: Fever (2)); Gemcitabine and Docetaxel (n=2: Nausea and vomiting (1), Fever (1)); Bicalutamide (n=1: Back pain (1)); Carboplatin (n=1: Hearing loss); Docetaxel and Carboplatin (n=1: Nausea and vomiting); Fluorouracil, Doxorubicin and Cyclophosphamide (n=1: Nausea); Gemcitabine and Carboplatin (n=1: Nausea and vomiting); Irinotecan (n=1: Fever); Oxaliplatin (n=2: Nausea and vomiting (1), Leukopenia (1)); Oxaliplatin and Capecitabine (n=1: Nausea and vomiting); Sorafenib (n=1: Renal failure)
A: Alimentary Tract and Metabolism agents (25, 6.8)	Insulin (n=11: Hypoglycemia (11)); Lactulose (n=3: Nausea (1), Diarrhea (1), Flatulence (1)); Metformin (n=3: Diarrhea (1), Hypoglycemia (2)); Ascorbic acid (n=2: Headache (1), Nausea (1)); Bisacodyl (n=2: Abdominal pain (2)); Metoclopramide (n=3: Headache (1), Drowsiness (1), Bronchospasm (1)); Lansoprazole (n=1: Vomiting)
P: Antiparasitic Products, Insecticides and Repellents (23, 6.3)	Metronidazole (n=23: Drowsiness (5), Nausea (4), Headache (3), Nausea and vomiting (2), Confusion (1), Dysuria (1), Vaginitis (1), Vertigo (1), Candidiasis (1), Malaise (1), Dysgeusia (1) Dizziness (1), Insomnia (1))
H: Systemic hormonal preparations, excl. Sex hormones and insulins (10, 2.7)	Dexamethasone (n=5: Malaise (2), Hyperglycemia (1), Hypertension (1), Nausea (1)); Hydrocortisone (n=4: Angioedema (1), Hypernatremia (1), Hypertension (2)); Prednisolone (n=1: Hypertension)
B: Blood and blood forming organs (9, 2.7)	Ferrous sulfate (n=3: Nausea (2), Abdominal pain (1)); Warfarin (n=2: Bleeding (2)); Potassium chloride (n=2: Gastric irritation (1), Abdominal pain); FeFol (n=1: Abdominal pain); Enoxaparin (n=1: Injection site induration)
R: Respiratory system agents (4, 1.1)	Bromhexine (n=1: Gastric irritation); Chlorpheniramine (n=1: Drowsiness); Cyproheptadine (n=1: Hypersensitivity reaction); Salbutamol (n=1: Palpitation)
V: Various (2, 0.5)	Kayexalate (n=2: Constipation (1), Vomiting (1))
G: Genito-urinary (1, 0.3) system and sex hormones	Sildenafil (n=1: Dizziness)

Notes: Bold: Drugs implicated in the ADRs listed.

Abbreviations: CNS, central nervous system; ISD, isosorbide dinitrate; FeFol, ferrous sulfate and folic acid.