Antimicrobial Drug-Utilisation Evaluation in a Medical ICU Using WHO AWaRe, ATC/DDD and Predefined Criteria

This M.Pharm Pharmacy Practice research work is a six-month prospective drug-utilisation evaluation (DUE) of antimicrobials in the medical intensive care unit of a tertiary-care teaching hospital. ICUs use more antibiotics per patient than any other area of a hospital, and India carries one of the highest burdens of antimicrobial resistance in the world. The Government of India's National Action Plan on AMR and the ICMR Antimicrobial Stewardship Programme both call for hospitals to measure how much and how well antimicrobials are used.

The study measures quantity using the WHO ATC/DDD methodology — defined daily doses per 100 bed-days, overall and by agent — and classifies every antibiotic by the WHO AWaRe (Access, Watch, Reserve) categories. It measures quality by auditing each antimicrobial course against predefined DUE criteria derived from the hospital antibiotic policy and the ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes: documented indication, cultures sent before the first dose, appropriate empirical choice, renal dose adjustment, de-escalation or review at 48–72 hours, and duration.

Data are analysed in SPSS: descriptive statistics, chi-square tests, and binary logistic regression to identify predictors of inappropriate use. The findings are fed back to the hospital's antimicrobial stewardship committee. The plan maps onto the MPP 304P → MPP 402P/403P research-work slots and requires Institutional Ethics Committee approval, which is why the protocol, consent waiver justification and data-protection plan are part of Phase I.

Abstract

A prospective observational drug-utilisation evaluation will be conducted for six months in the medical ICU of a tertiary-care teaching hospital. All adult patients receiving at least one systemic antimicrobial will be included. Antimicrobial consumption will be expressed as DDD/100 bed-days using the WHO ATC/DDD index and classified by WHO AWaRe. Appropriateness will be assessed against predefined criteria. Predictors of inappropriate use will be identified by logistic regression.

Introduction

Drug-utilisation research, as defined by WHO, studies the marketing, distribution, prescription and use of drugs in society, with special emphasis on the resulting medical, social and economic consequences. A drug-utilisation evaluation goes one step further: it compares actual use with explicit criteria and triggers corrective action. Antimicrobials are the most important target for DUE in ICUs because inappropriate use drives resistance, Clostridioides difficile infection, toxicity and cost.

Review and research gap

Indian ICU studies frequently report the percentage of patients receiving antibiotics and the most-used agents. Fewer studies combine standardised consumption metrics (DDD/100 bed-days) with AWaRe classification and a criteria-based appropriateness audit in the same cohort, and fewer still model the predictors of inappropriate use. This study combines all three.

Research questions

1. What is the antimicrobial consumption in DDD/100 bed-days, and what proportion falls in Access, Watch and Reserve groups?
2. What proportion of antimicrobial courses meet predefined appropriateness criteria?
3. Which patient and treatment factors predict inappropriate use?

Feasibility

• Setting: a 20-bed medical ICU admits enough patients to reach the sample in six months.
• Support: the clinical pharmacology department and the stewardship committee act as co-guides.
• Resources: WHO ATC/DDD index and AWaRe list are freely available; SPSS is licensed by the college.
• Ethics: IEC approval, confidentiality and feedback without naming prescribers.

Expected outcome

A baseline consumption and quality profile for the ICU that the stewardship committee can repeat every year, and a clear list of the criteria most often missed.

Critically ill patients frequently receive broad-spectrum antimicrobials empirically, often in combination, and these are not always reviewed once culture results are available. In Indian ICUs this pattern contributes to high rates of carbapenem-resistant Enterobacterales, resistant Acinetobacter and MRSA, avoidable adverse effects and high treatment costs. Many hospitals have an antibiotic policy on paper but no routine measurement of how much of each agent is used, how much of it belongs to the WHO Watch and Reserve groups, or how often use meets basic stewardship criteria such as sending cultures first and de-escalating at 48–72 hours.

Without this data, stewardship committees cannot target their interventions. The problem addressed by this research is therefore the lack of standardised quantitative and qualitative data on antimicrobial use in the medical ICU, and the lack of evidence on which factors predict inappropriate use, which a clinical pharmacist is well placed to generate.

In scope

• Adult patients (≥ 18 years) in the medical ICU receiving at least one systemic antimicrobial (ATC J01, J02, and oral vancomycin/metronidazole for C. difficile) during six months.
• Quantity (DDD/100 bed-days), AWaRe classification, appropriateness audit, predictors and antimicrobial cost.
• Anonymised feedback to the stewardship committee.

Out of scope

• Surgical ICU, paediatric and neonatal units.
• Antivirals, antituberculosis and antimalarial drugs.
• Interventional stewardship (changing therapy) — the study is observational; the clinical team decides all treatment.
• Clinical outcome comparisons requiring a controlled design.

Study design: prospective, observational, hospital-based drug-utilisation evaluation.

Setting and duration: medical ICU of a tertiary-care teaching hospital; six months of data collection within the research-work period.

Sample size: based on the proportion of inappropriate antimicrobial courses. With no reliable local estimate, p = 0.5 was used with Z = 1.96 and absolute precision d = 0.07: n = 1.96² × 0.5 × 0.5 / 0.07² ≈ 196; with 5% allowance for incomplete records, n = 206 patients. All eligible admissions are enrolled consecutively until the sample and the six-month period are both complete; consumption metrics use every patient-day in the period.

Inclusion criteria: age ≥ 18 years; ICU stay ≥ 24 hours; at least one systemic antimicrobial.

Exclusion criteria: patients transferred out within 24 hours, antimicrobials given only as single-dose surgical prophylaxis, and patients enrolled in an interventional drug trial.

Data collection: a structured form captures demographics, diagnosis, APACHE II score, comorbidities, renal function (creatinine clearance by Cockcroft–Gault), cultures and sensitivity, each antimicrobial with dose, route, frequency, start and stop dates, reasons for change, and outcome. Data are taken daily from case sheets, medication charts and the microbiology report system.

Consumption: DDD/100 bed-days = (total grams of each agent ÷ WHO DDD) ÷ total patient-days × 100, calculated in Excel with the current ATC/DDD index.

Appropriateness criteria (finalised with the stewardship committee before data collection): documented indication; culture sent before first dose; empirical choice consistent with policy; correct dose and renal adjustment; review/de-escalation at 48–72 h; duration within guideline. A course is inappropriate if any criterion fails.

Statistical analysis (SPSS): mean ± SD or median (IQR); chi-square or Fisher's exact test for associations; binary logistic regression (inappropriate use yes/no) with age, APACHE II, number of antimicrobials, culture sent, renal impairment and length of stay as candidate predictors; odds ratios with 95% CI; p < 0.05.

Ethics: Institutional Ethics Committee approval (committee registered with CDSCO), consistent with the ICMR National Ethical Guidelines 2017; written informed consent from the patient or legally acceptable representative, or a consent waiver if the IEC grants one for record-based observational data; coded data, no prescriber names in the dissertation.