Infectious Shock and Toxic Shock Syndrome Diagnoses in Hospitals, Colorado, USA

Michael A. Smit, Ann-Christine Nyquist, and James K. Todd

Author affiliations: Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA (M.A. Smit); University of Colorado School of Medicine, Aurora, Colorado, USA (A.-C. Nyquist, J.K. Todd); Colorado School of Public Health, Aurora (A.-C. Nyquist, J.K. Todd); Children’s Hospital Colorado, Aurora (A.-C. Nyquist, J.K. Todd)

Abstract

In Colorado, USA, diagnoses coded as toxic shock syndrome (TSS) constituted 27.3% of infectious shock cases during 1993–2006. The incidence of staphylococcal TSS did not change significantly overall or in female patients 10–49 years of age but increased for streptococcal TSS. TSS may be underrecognized among all ages and both sexes.

First described in 1978, toxic shock syndrome (TSS) is a severe febrile illness now confirmed to be caused by exotoxin-producing strains of Staphyloccocus aureus and Streptococcus pyogenes (1). Investigations based on extensive chart review and/or microbiology laboratory data suggest little or no decrease in overall TSS incidence and an increase in streptococcal TSS (2–4). Given the persistence and severity of TSS and the differences in its treatment from other causes of septic shock, its evolving epidemiology needs to be accurately monitored (5–7). To this end, we assessed International Classification of Diseases, Ninth revision, Clinical Modification (ICD-9-CM)–coded TSS cases in Colorado, USA.

The Study

In 2007, we queried the Colorado Hospital Association database for ICD-9-CM codes that identified diagnoses consistent with infectious shock or TSS unrelated to pregnancy or childbirth (8). The study population comprised Colorado residents 1–65 years of age, selected by ZIP code of residence, who were discharged from Colorado hospitals during 1993–2006. Presumptive cases of “infectious shock” were 1) TSS or meningococcal shock of any diagnostic code (040.82, 040.89, 036.3); 2) principal diagnosis of hypotension or shock (785.50, 785.59, 998.0, 458.0, 796.3) plus any secondary diagnosis of staphyloccocal infection (038.1x, 041.1x, 482.4x); streptococcal infection (041.0x, 482.3x, 034.0, 038.1); scarlet fever (034.1); or bacteremia, septicemia, or other infection (code list available from authors); and 3) principal diagnosis of bacteremia, septicemia, staphyloccocal infection, streptococcal infection, other infection, or scarlet fever, plus any secondary diagnostic code of shock (see above codes). Infectious shock was further grouped into 3 code categories: 1) TSS-specific code: code for TSS (040.82 or 040.89) in any diagnostic field; 2) possible TSS code: infectious shock code without a specific code for TSS but with a code for infection with S. aureus (038.11, 041.11, 042.41) or S. pyogenes(041.01, 482.31) or with scarlet fever (034.1); and 3) infectious shock code, not TSS: infectious shock not otherwise classified. TSS was further designated as “strep” if it was associated with any code for S. pyogenes; all other TSS cases were assumed to be caused by S. aureus and were designated as “staph.” All case definitions were based on ICD-9-CM codes assigned by the discharging hospital.