Background and importance Clinical practice guidelines recommend oseltamivir in hospitalised patients with influenza but its use in clinical practice is limited.

Aim and objectives To determine the criteria for use of oseltamivir in hospitalised patients and to analyse the prescription of concomitant antibiotics.

Material and methods An observational, descriptive, retrospective study was conducted in patients treated with oseltamivir (November 2018–February 2019) in a second level hospital. Electronic medical history was used as the source of information. Variables collected: date of admission/discharge, clinical service, polymerase chain reaction (PCR), age, risk factors, dosing regimen/adjustment, duration of treatment, complications, return to hospital and concomitant antibiotics prescribed. SPSS was used for statistical analysis.

Results Oseltamivir was prescribed in 160 patients, mostly from the internal medicine service (58.1%) and pneumology (22.5%), with an average entry duration of 8 days.

PCR was performed in 111 patients (69.4%) and confirmed the diagnosis in 103 (64.37%), such as flu A. In eight patients with negative PCR, oseltamivir was discontinued. Cases confirmed by age range were: 3 (<18 years), 31 (18–65 years) and 69 (>65 years). The most common pathological history was high blood pressure (HTA) (27.7%), dyslipaemia (19.3%), cardiovascular disease (18.5%), lung disease (14.7%), diabetes (10.1%), immunosuppression (6.3%) and chronic kidney disease (CKD) (7.8%). As risk factors, 21.4% were active smokers, 14.6% were obese and there were no pregnant women. Regarding complications, 8.7% required the intensive care unit, 3.9% died and 11.7% returned to hospital.

The most common oseltamivir dosing regimen was 75 mg/12 hours. In 13 patients with CKD, 75% who had a ClCr 10–30 mL/min had the dose adjusted to 30 mg/24 hours. In contrast, 11.11% of patients with ClCr 30–60 mL/min, the dose was adjusted to 30 mg/12 hours. Duration of treatment in 52% was 5 days. Seventy-three patients received empiric levofloxacin, 67 ceftriaxone, 35 amoxicillin/clavulanic and 11.8% received no antibiotic.

Conclusion and relevance PCR was not performed in all patients suspected of flu virus infection. The population >65 years of age was the most affected by the virus, with HTA and smoking being the main risk factors. Oseltamivir was used at the correct dose, but treatment duration greater than or less than 5 days was not warranted. Adjustment for CKD was not always taken into account. Overuse of antibiotics was confirmed in patients where an antiviral might have been sufficient to treat the influenza.

References and/or acknowledgements No conflict of interest.