Health services utilization, work absenteeism and costs of pandemic influenza A (H1N1) 2009 in Spain: a multicenter-longitudinal study

Abstract

Background: The aim of this study was to estimate healthcare resource utilization, work absenteeism and cost per patient with pandemic influenza (H1N1)2009, from its beginning to March 2010, in Spain. We also estimated the economic impact on healthcare services.

Methods and findings: Longitudinal, descriptive, multicenter study of in- and outpatients with confirmed diagnosis of influenza A (H1N1) in Spain. Temporal distribution of cases was comparable to that in Spain. Information of healthcare and social resources used from one week before admission (inpatient) or index-medical visit (outpatient) until recovery was gathered. Unit cost was imputed to utilization frequency for the monetary valuation of use. Mean cost per patient was calculated. A sensitivity analysis was conducted, and variables correlated with cost per patient were identified. Economic impact on the healthcare system was estimated using healthcare costs per patient and both, the reported number of confirmed and clinical cases in Spain. 172 inpatients and 224 outpatients were included. Less than 10% were over 65 years old and more than 50% had previous comorbidities. 12.8% of inpatients were admitted to the Intensive Care Unit. Mean length of hospital stay of patients not requiring critical care was 5 days (SD = 4.4). All working-inpatients and 91.7% working-outpatients went on sick leave. On average, work absenteeism was 30.5 days (SD = 20.7) for the first ones and 9 days (SD = 6.3) for the latest. Caregivers of 21.7% of inpatients and 8.5% of outpatients also had work absenteeism during 10.7 and 4.1 days on average respectively. Mean cost was €6,236/inpatient (CI95% = 1,384-14,623) and €940/outpatient (CI95% = 66-3,064). The healthcare economic burden of patients with confirmed influenza was €144,773,577 (IC95% 13,753,043-383,467,535). More than 86% of expenditures were a result of outpatients' utilization.

Conclusion: Cost per H1N1-patient did not defer much from seasonal influenza estimates. Hospitalizations and work absenteeism represented the highest cost per patient.

Figure 1. Sample selection flow chart.

Figure 2. Direct healthcare and indirect¹ costs' distribution according to patient's group.

¹Indirect cost is derived from work absenteeism of patient and caregiver and paid caregiver. A. Inpatients admitted to the intensive care unit at any time of the hospitalization. (n = 20). B. Inpatients hospitalized exclusively at the general ward. (n = 136). C. Outpatients. (n = 224).

Figure 3. Mean cost per patient and its 95%CI based on the sensitivity analysis.

Figure 4. Correlation of cost per patient and the main input variables (Spearman's rank).

A. Inpatients. B. Outpatient. Abbreviations: GW: General Ward, ICU: Intensive Care Unit, GP: General Practitioner, ED: Emergency Department.