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 Table of Contents  
Year : 2022  |  Volume : 18  |  Issue : 4  |  Page : 172-176

Patterns and outcomes of empirical antimicrobial use in elderly outpatients: A pilot observational study from North India

1 Department of Pharmacology, Lady Hardinge Medical College, New Delhi, India
2 Department of Pharmacology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
3 Department of Geriatric Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Date of Submission30-Sep-2022
Date of Decision01-Dec-2022
Date of Acceptance06-Dec-2022
Date of Web Publication27-Dec-2022

Correspondence Address:
Dr. Upinder Kaur
Department of Pharmacology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiag.jiag_55_22

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Introduction: Despite the rampant use of antimicrobials in health-care settings, the safety and clinical outcome data of antimicrobials are scarce in the elderly population. The main aim of this study is to assess the prescription pattern, therapeutic gains, and adverse reactions resulting out of antimicrobial use in elderly outpatients. Subjects and Methods: This was a prospective observational study conducted for 7 months from June 2019 to December 2019 in elderly patients visiting the geriatric outpatient department of a tertiary hospital of North India. Primary outcomes included clinical improvement as well as the incidence and type of adverse drug reactions (ADRs) observed with antimicrobial use. Results: Of 110 participants recruited, 107 were assessed for clinical outcomes. The common indications of antimicrobial use were lower respiratory tract infection (48.6%), urinary tract infection (18.7%), and worm infestations (14%). Macrolides (57%) and beta-lactams (43%) were the commonly prescribed individual antimicrobials. Outcome-wise, clinical improvement was seen in 91.3%, 88.5%, and 14.3% of patients receiving beta-lactams, macrolides, and antiprotozoals, respectively. ADRs occurred in 17.7% of participants and gastrointestinal disturbance was the commonly reported ADR. Beta-lactams and macrolides were responsible for the majority of ADRs, in 19.6% and 13.1% of participants, respectively. No association of antimicrobial-associated clinical responses or ADRs was observed with demographics and underlying comorbidities. Conclusions: Elderly patients with respiratory tract infections showed improvement with empirical extended-spectrum beta-lactams and azithromycin therapy. The response was suboptimal to empirically selected antiprotozoal therapy. Elderly patients are at increased risk of ADRs. Close to one out of every five elderly prescribed beta-lactams may develop ADR to the antimicrobial agent. Larger clinical studies are required to predict the risk factors of ADRs and poor responsiveness to antimicrobials.

Keywords: Adverse drug reactions, antimicrobials, beta-lactams, geriatric, pharmacovigilance, prescription patterns

How to cite this article:
Ojha B, Singh A, Chakrabarti SS, Kaur U. Patterns and outcomes of empirical antimicrobial use in elderly outpatients: A pilot observational study from North India. J Indian Acad Geriatr 2022;18:172-6

How to cite this URL:
Ojha B, Singh A, Chakrabarti SS, Kaur U. Patterns and outcomes of empirical antimicrobial use in elderly outpatients: A pilot observational study from North India. J Indian Acad Geriatr [serial online] 2022 [cited 2023 Jan 29];18:172-6. Available from: http://www.jiag.com/text.asp?2022/18/4/172/365779

  Introduction Top

Elderly 60 years of age and above constitute more than 12% of the global population. The percentage is expected to increase to more than 22% with a major contribution from low-and middle-income countries.[1] A major cause of morbidity and mortality in the elderly stems from infectious diseases which are nearly two times more common in the elderly compared to adults.[2] The increased vulnerability of the elderly to infections translates to a considerably high rate of antibiotic prescription in aged patients.[3] Pharmacotherapy in the elderly is complex because of aging-related physiological and pharmacological changes, presence of multiple chronic diseases and polypharmacy. Elderly patients are also at increased risk of developing adverse drug reactions (ADRs) which apart from causing morbidity, lead to premature discontinuation of medicines, and failure to achieve successful outcomes. Despite the rampant use of antimicrobials in the geriatric population and the existing complexities of geriatric pharmacotherapy, studies assessing the patterns and outcomes of antimicrobial use in elderly patients are scarce. Scanty also is the evidence on antimicrobial-associated ADRs specific to the elderly. Knowledge of antibiotic patterns and outcomes of antibiotic use is critical in formulating age group-specific guidelines on antibiotic prescription. The main aim of this prospective study is to assess the patterns, clinical responses, and adverse reactions of antibiotic use in elderly patients visiting the geriatric outpatient department.

  Subjects and Methods Top

Study design

This was a prospective observational study conducted over a period of 7 months from June 2019 to December 2019. The study was undertaken in the outpatient clinic of the department of geriatric medicine of a major teaching and research university hospital of northern India.

Study participants

Patients over 50 years of age were allowed registration in the geriatric outpatient department (OPD) during the study period and were screened for the study. Patients who were prescribed at least one antimicrobial irrespective of the route and who provided consent to participate in the study were included in the study. Because of feasibility concerns, patients receiving antitubercular drugs were excluded as were the patients who refused to participate.

Ethical permission

The study was conducted after obtaining permission from the institute ethics committee. Written informed consent was obtained from the patients or their legal guardians.

Data collection and outcomes measured

Data was collected in a predesigned case report form and pertained to the patient's demographics, underlying diseases, concomitant medications, specifics related to the prescribed antimicrobial agent, clinical response, and types of ADRs to antimicrobials. Patients were monitored during the next scheduled OPD visit after a minimum period of 7 days of antimicrobials. Clinical response was assessed by the physician depending on the patient's symptoms and physical examination. The response was categorized as “satisfactory” if ≥70% improvement in symptoms was reported by the patients and nonsatisfactory if the response was <50%.


Clinical improvement in symptoms of the underlying infection was the primary outcome measure and incidence and types of ADRs to antimicrobials were the secondary outcome measures.

Sample size

In the absence of similar studies, this pilot study was planned to be conducted in a minimum of 100 patients. The enrollment of patients was stopped after 110 patients were enrolled.

Statistical analysis

Data were recorded as means and medians for nonskewed and skewed quantitative variables, respectively. Antimicrobial use, clinical response, and ADRs were recorded in frequencies and percentages. The Chi-square test was used to measure the association if any between the occurrence of ADRs, clinical response, and baseline characteristics. Depending upon the normality of the data, Student t-test or Mann–Whitney test was applied for the comparison of quantitative variables. P < 0.05 was considered statistically significant. SPSS version 16 (SPSS Inc., Chicago, US) was used for statistical analysis.

  Results Top

A total of 110 patients were initially included out of whom 2 did not receive the prescribed antimicrobial and 1 was lost to follow-up. The remaining 107 were hence included for the analysis. Demographics and baseline characteristics of patients are mentioned in [Table 1].
Table 1: Baseline characteristics of patients enrolled in the study (n=107)

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The median (Q1, Q3) number of diagnoses in the study population was 3 (2, 3). Among the underlying diseases, preexisting lung disease and hypertension were the common comorbidities seen in 53 (49.5%) and 45 (42.1%), respectively. The median (Q1, Q3) number of medications was 6 (5, 8). Acid-lowering drugs were the most common concomitant medication, prescribed in 60 (56.1%) patients, followed by analgesics/anti-inflammatory agents (n = 43, 40.2%). Leukotriene antagonists and antihistaminic agents were each advised in 36 (33.6%). The median (Q1, Q3) number of antimicrobial agents was 1 (1, 2). Common indications for antimicrobial prescriptions are also mentioned in [Table 1]. Lower respiratory tract infections (LRTIs) were the indication for prescription of antimicrobials in 52 (48.6%), followed by urinary tract infections (UTIs) (20, 18.7%) and suspected worm infestation (15, 14%).

Chemical subgroup-wise, the most common prescribed class of antibiotics was macrolides (61, 57%), followed by beta-lactams (46, 43%) [Table 2]. With respect to therapeutic indications, both these classes were largely preferred for respiratory tract infections. Individually, azithromycin was the most common prescribed antimicrobial (61, 57%), followed by amoxycillin–clavulanic acid (38, 35.5%) and nitrofurantoin (13, 12.1%) The latter was the preferred antimicrobial for UTIs.
Table 2: World Health Organisation-Anatomical Therapeutic Chemical classification of prescribed antimicrobials, clinical response rates, and rates of adverse drug reactions to antimicrobials

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Clinical response to antimicrobials and association with baseline characteristics

In patients prescribed beta-lactams and macrolides, clinical response as assessed by the physician was satisfactory in 91.3% and 88.5%, respectively [Table 2]. Nearly 77% of patients prescribed nitrofurantoin for UTIs responded satisfactorily to the drug. Response was modest for fluoroquinolones (54.5%) and for anthelminthic (57.1%) and marginal for antiprotozoals (14.3%), prescribed largely for suspected gastrointestinal infections. No association of clinical response to antimicrobials was observed with baseline characteristics such as age (P = 0.10), sex (P = 0.75), number of drugs (P = 0.65), number of diagnoses (P = 0.14), and comorbidities such as diabetes (P = 0.35) and hypertension (P = 0.42).

Adverse drug reactions to antimicrobials and association with baseline characteristics

Among the 107 participants taking the prescribed antimicrobials, 19 ADRs were observed in 16 participants (17.7%) [Table 3]. Gastrointestinal tract (GIT) abnormalities were the predominant ADRs, and diarrhea was the most common individual ADR [Table 3]. Close to 9.3% of patients taking antimicrobials reported GIT disturbances. Class-wise, beta-lactams and macrolides were responsible for the majority of ADRs (10/19, 52.6%). Incidence-wise, beta-lactams caused ADRs in 19.6%, followed by azithromycin which caused ADRs in 13.1% [Table 2]. ADRs caused premature discontinuation of the antimicrobial in 4 (3.7%) patients. No association of ADRs was observed with baseline characteristics such as age (P = 0.09), sex (P = 0.84), comorbidities such as diabetes (P = 0.91), hypertension (P = 0.34), number of drugs (P = 0.26), and number of diagnoses (P = 0.69).
Table 3: Frequency and patterns of adverse drug reactions with antimicrobials

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  Discussion Top

Elderly are more prone to infections due to aging-related immunosenescence and the presence of multiple comorbidities. Compared to adults, they are more likely to receive antibiotics early as well as for a prolonged duration.[4] Prescription rates of 1364.3 antibiotics/1000 persons translating to >1 antibiotic/person/year have been documented for elderly outpatients in the United States.[3],[5] Despite the common encounters of antimicrobials in routine prescriptions, studies assessing the patterns and outcomes of antibiotic use in elderly patients visiting the OPDs are scarce, more so from developing countries. Only a few have evaluated the antimicrobial patterns in hospitalized elderly.[6] Unexplored also are the characteristics and outcomes of ADRs associated with antibiotic use in the elderly. In the present pilot study, LRTIs accounted for the majority of antimicrobial use (48.6%), followed by UTIs (18.7%), indicating the distribution of common infections in the elderly in the North Indian geriatric practice. Satisfactory response was achieved in the majority of elderly receiving extended-spectrum beta-lactams, macrolides, and nitrofuran derivatives for underlying infections as decided by clinical judgment. Azithromycin and amoxicillin–clavulanic acid, thus, may serve as good empirical options for common respiratory tract infections in the elderly, and nitrofurantoin as a wise option for outpatient treatment of UTIs. In resource-limited settings where intensive investigations are not feasible due to patients coming from far away and also issues of laboratory support, these antimicrobials can be selected as first-line therapy. Around 19% of patients showed suboptimal response with empirical antimicrobial treatment. Only 57% of patients responded symptomatically to anthelmintics prescribed for suspected worm infections. The implications of this are unclear as it may be prudent to perform occasional deworming in regions of India where hygiene standards may be poor. Most such prescriptions were empirical and without laboratory support, hence a low response may be as expected. Response rate was further lower (14%), in patients receiving antiprotozoals for suspected gastrointestinal infections. Most of these cases were treated empirically with a combination of norfloxacin–tinidazole. Although the number of patients with suspected gastrointestinal infections was few (n = 7), irritable bowel syndrome (IBS) was suspected concurrently in more than half of them. Future studies focused on the elderly with gastrointestinal infections are needed to support the decision and choice of empirical antimicrobial use in such cases. Stool culture sensitivity tests can be performed in nonrespondent patients to guide the selection of proper therapy. The question of whether suspected cases of IBS should be prescribed a course of antibiotics in a developing country where bacterial and protozoal infections are rampant also needs further exploration.

Around 15% of elderly receiving antimicrobials developed ADRs in the present study. Premature discontinuation because of adverse effects was observed in close to 4%. These rates are higher than the ADR rate because of antibiotics in the adult population. Studies evaluating the ADR profile of antibiotics have been conducted largely in the hospitalized adult population.[7],[8] A lower rate (1.1%) of ADRs has been reported with antimicrobials in adults. Class-wise, beta-lactams and fluoroquinolones are the common culprits, and system-wise, the dermatological system is the most common system affected by ADRs in adults.[7],[8],[9] Exanthems and renal insults are the common manifestations of antimicrobial-related ADRs in hospitalized adults. Another retrospective study involving a relatively older hospitalized population (median age: 59 years) showed a relatively high rate (20%) of ADRs due to antimicrobials. Gastrointestinal manifestations and renal insults were the commonly noted adverse effects in this study.[10] The incidence as well as patterns of antimicrobial-related ADRs thus differ in adults and the elderly. The GIT was the commonly affected organ system and diarrhea was the most common adverse effect noticed in the present study, occurring in around 5% of patients. Lower rates of cutaneous reactions with antibiotics in the elderly can be related to aging-related immunosenescence. Class-wise, beta-lactams were responsible for the majority of the adverse effects, similar to the findings of other studies assessing antimicrobials in adults.[7],[8] Neither clinical response nor the occurrence of ADRs with antibiotics shared any significant association with age, gender, comorbidities, and the number of drugs.


The present study has many limitations. It was conducted in a small number of patients and findings at present have limited implications. Recruitment of patients was affected after OPDs were shut down during the COVID-19 pandemic. Patients on antitubercular drugs were excluded as such patients require longer monitoring which was not feasible. Only one patient in the present study was prescribed a parenteral antimicrobial. Larger studies with adequate representation of oral and parenteral antimicrobials are required in future for better evaluation. A larger sample size will also help in the detection of rare, atypical, and severe ADRs associated with antimicrobials. ADRs recovered spontaneously in the majority and no active investigations such as stool examination for C. difficile and electrocardiogram (ECG) monitoring for QT interval were done. Macrolides and fluoroquinolones are particularly linked with ECG changes. With the study showing macrolides as the most common prescribed class, such investigations can be incorporated in the future for the generation of elderly-specific safety data. Clinical response was assessed subjectively by the treating physician based on patient response and physical examination. Incorporation of blood investigations such as complete blood counts and radiological investigations such as chest radiographs and others can be done in the future for a detailed evaluation of patients.

  Conclusions Top

Majority of the elderly patients with respiratory tract infections showed improvement with empirical treatment based on extended-spectrum beta-lactams and azithromycin, supporting the use of this combination as an empirical therapy in such cases. Likewise, clinical response was favorable with nitrofurantoin prescribed empirically for lower UTIs. Nitrofurantoin may hence still be a useful empirical agent in such cases. A modest improvement was seen with anthelminthic and gastrointestinal infections responded sub-optimally to norfloxacin–tinidazole-based empirical treatment. Future studies with adequate representation of elderly with gastrointestinal infections are required to support the decision as well as the choice of empirical antimicrobial agent. Compared to adults, the ADR rate with antimicrobials was manifold higher in the elderly. Nearly one out of five elderly patients may develop adverse reactions to beta-lactams, largely in the form of gastrointestinal disturbances. This pilot study emphasizes the need for larger studies in developing countries for better evaluation of antimicrobial-related efficacy parameters and for a comprehensive understanding of antimicrobial-specific safety profiles in the elderly population.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Ageing and Health. Available from: https://www.who.int/news-room/fact-sheets/detail/ageing-and-health. [Last accessed on 2022 Sep 10, Last updated on 2022 Sep 16].  Back to cited text no. 1
Paul K, Singh J. Emerging trends and patterns of self-reported morbidity in India: Evidence from three rounds of national sample survey. J Health Popul Nutr 2017;36:32.  Back to cited text no. 2
Olesen SW, Barnett ML, MacFadden DR, Lipsitch M, Grad YH. Trends in outpatient antibiotic use and prescribing practice among US older adults, 2011-15: Observational study. BMJ 2018;362:k3155.  Back to cited text no. 3
Hayward GN, Moore A, Mckelvie S, Lasserson DS, Croxson C. Antibiotic prescribing for the older adult: Beliefs and practices in primary care. J Antimicrob Chemother 2019;74:791-7.  Back to cited text no. 4
Kabbani S, Palms D, Bartoces M, Stone N, Hicks LA. Outpatient antibiotic prescribing for older adults in the United States: 2011 to 2014. J Am Geriatr Soc 2018;66:1998-2002.  Back to cited text no. 5
Bist A, Kulkarni GP, Gumma KM. Study of patterns of prescribing antibiotics in geriatric patients admitted to the medical wards in a tertiary care hospital. Int J Basic Clin Pharmacol 2016;5:155-8.  Back to cited text no. 6
Arulappen AL, Danial M, Sulaiman SA. Evaluation of reported adverse drug reactions in antibiotic usage: A retrospective study from a tertiary care hospital, Malaysia. Front Pharmacol 2018;9:809.  Back to cited text no. 7
Jung IY, Kim JJ, Lee SJ, Kim J, Seong H, Jeong W, et al. Antibiotic-related adverse drug reactions at a tertiary care hospital in South Korea. Biomed Res Int 2017;2017:4304973.  Back to cited text no. 8
Richa, Tandon VR, Sharma S, Khajuria V, Mahajan V, Gillani Z. Adverse drug reactions profile of antimicrobials: A 3-year experience, from a tertiary care teaching hospital of India. Indian J Med Microbiol 2015;33:393-400.  Back to cited text no. 9
Tamma PD, Avdic E, Li DX, Dzintars K, Cosgrove SE. Association of adverse events with antibiotic use in hospitalized patients. JAMA Intern Med 2017;177:1308-15.  Back to cited text no. 10


  [Table 1], [Table 2], [Table 3]


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