HOSPITALIZATIONS FOR VARICELLA IN THE UNITED STATES IN THE PRE-VACCINATION ERA, 1988-1995

Karin Galil (1), Felix Lin (2), Jane Seward (1)
(1) National Immunization Program, Centers for Disease Control and Prevention, Atlanta, GA, (2) University of New Mexico School of Medicine, Albuquerque, NM

Background:
Varicella epidemiology is expected to alter with the widespread use of an effective vaccine.

Objective:
To describe the burden of hospitalizations due to varicella in the United States immediately prior to the widespread use of varicella vaccine.

Methods:
We analyzed data from the National Hospital Discharge Survey (NHDS) from 1988 to 1995. NHDS samples medical records of inpatients discharged from a national sample of non-Federal short-stay hospitals. We searched all diagnostic positions for varicella (052), excluding discharges with coexisting herpes zoster. To eliminate cases for which varicella was incidental to the hospitalization, we included cases only if: varicella or a well-described varicella complication was the principal discharge diagnosis; or varicella pneumonitis or varicella encephalitis was included among the diagnosis in any position; or varicella was diagnosed in an immunocompromised person.

Results:
There were approximately 11,100 hospitalizations annually, 65.9% were among children <15 years. Males (56.1%) were hospitalized more commonly than females. The most common complications recorded were soft tissue infections (20.3%), viral pneumonia (20.0%), fluid/electrolyte disturbances (19.5%) and bacterial pneumonia (9.9%). Encephalitis was rare. Most (61.7%) persons hospitalized for varicella had no diagnoses suggesting underlying medical conditions. 14.4% of persons hospitalized for varicella had diagnoses for immunocompromising conditions. The most common other coexisting diagnoses were cardiac conditions (4.5%), anemia and blood dyscrasias (3.2%), neurologic conditions (2.6%) and pulmonary conditions (2.3%). The mean length of hospitalization was 5.5 days, corresponding to 61,045 days of hospitalization annually.

Conclusion:
Although not commonly recognized, varicella may cause considerable morbidity and results in a greater burden of hospitalization than was reported previously. Future analyses of NHDS data can be used to assess the impact of the varicella vaccination program.

Corresponding Author: Karin Galil, MD, MPH, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop E-61, Atlanta, GA 30333, USA