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Open Access Highly Accessed Research article

The disease burden of pertussis in adults 50 years old and older in the United States: a retrospective study

Catherine Balderston McGuiness1*, Jerrold Hill1, Eileen Fonseca1, Gregory Hess12, William Hitchcock3 and Girishanthy Krishnarajah4

Author Affiliations

1 IMS Health, One IMS Drive, Plymouth Meeting, Pennsylvania, PA, 19462, USA

2 Leonard Davis Institute for Health Economics and Policy, University of Pennsylvania, 3641 Locust Walk, Pennsylvania, PA, 19104, USA

3 La Jolla Pediatrics, 4520 Executive Drive, Suite 350, San Diego, CA, 92121, USA

4 GlaxoSmithKline, One Franklin Plaza, Pennsylvania, PA, 19104, USA

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BMC Infectious Diseases 2013, 13:32  doi:10.1186/1471-2334-13-32

Published: 23 January 2013

Abstract

Background

While the incidence of pertussis has increased in adolescents and adults in recent years in the U.S., little is known about the incidence and economic burden of pertussis in older adults. This study provides evidence of the incidence of pertussis and direct medical charges associated with pertussis episodes of care (PEOCs) in adults aged 50 years and older in the U.S.

Methods

PEOCs were divided into periods before and after the initial pertussis diagnosis was made (i.e., the index date) to capture any conditions immediately preceding the pertussis diagnosis that may have represented misdiagnoses and subsequent conditions that may have represented sequelae. Data were extracted from IMS's recently acquired SDI databases of longitudinal, patient-level practitioner claims and hospital operational billing records collected from private practitioners and hospitals, respectively, across the U.S. Patients 50 years and older with one or more ICD-9-CM diagnoses for pertussis/whooping cough and/or a laboratory test positive for Bordetella pertussis between 1/1/2006 and 10/31/2010 were eligible for study inclusion. Resource utilization and charges (i.e., unadjudicated claims) associated with the patient's physician and hospital care were analyzed. The nationally projected incidence of pertussis was estimated using a subsample of patients with the required data necessary for projection.

Results

Estimated incidence of diagnosed pertussis ranged from 2.1-4.6 cases per 100,000 people across the two age groups (50–64 and [greater than or equal to] 65) during the years 2006 to 2010. The analysis of charges included 5,748 patients [greater than or equal to] 50 years of age with pertussis. Average charges across the entire episode of care were $1,835 and $14,428 per patient in the outpatient and inpatient settings, respectively. The average number of outpatient (i.e., private practitioner) visits was 2 per patient in both the pre-index and post-index periods.

Conclusions

In the U.S., the incidence of diagnosed pertussis in adults 50 years and older has increased between 2006 and 2010. Healthcare utilization and charges associated with pertussis are substantial, suggesting the need for additional prevention and control strategies and a higher degree of clinical awareness on the part of health care providers. Additional research regarding pertussis in older populations is needed to substantiate these findings.

Keywords:
Pertussis; Whooping cough; Health economics; Adults; Elderly