Cost Burden of Hospital-Onset CDI Higher Than Community-Associated CDI

Costs related to clostridioides difficile infection (CDI) were highest in patients between the ages of 25 and 64 with hospital onset (HO) CDI and lowest in those with community-associated (CA) CDI treated outside a hospital, according to a study published in Open Forum Infectious Diseases.

The researchers explained that CDI is often associated with morbidity, death, and increased healthcare costs in older adults, but not a lot is known regarding the effects of CDI in younger adults, especially economically. Because of this, they calculated CDI-related health care costs in patients aged 25 to 64 years with HO CDI, community onset-health care facility association (HCFA) CDI, and CA CDI compared with control patients. They also calculated attributable costs in patients with HCFA and CA CDI that were treated in a hospital versus those treated outside a hospital to determine treatment site–related costs.

The study used data from the 2010 to 2017 Merative MarketScan Commercial Database, which includes medical claims for US residents covered primarily by employer-sponsored private health insurance. Codes from the International Classification of Diseases 9th Revision (ICD-9) and 10th Revision, Clinical Modification (ICD-10-CM) were used to identify patients with CDI; the researcher used patients’ 1st episodes for analysis.

To create their study population, the researchers explained that they initially matched patients with CDI 1 to 4 with uninfected individuals based on age, the definition of CDI surveillance, and CDI year. They explained that they assigned control patients index dates to match the distribution of CDI case onset dates and classified them into “standard surveillance definitions based on their location on the index date and recent treatment in a health care facility.”

After, the researchers explained that they restricted the population to patients with CDI and controls with available data at least 1 year before and after the CDI index date. They also analyzed costs for HCFA and CA groups based on whether the patients were hospitalized during the CDI episode, which they frequency matched to controls. Lastly, the researchers randomly excluded excess patients to keep a 4-to-1 ratio of controls to patients who experienced CDI.

The study population consisted of 5135 patients with HO CDI and 20,484 respective control patients; 6880 patients with community onset-HCFA CDI and 27,520 respective control patients; and 17,773 patients with CA CDI and 71,093 respective control patients.

The researchers utilized medical claims from the prior year and up to the index date to define patients’ health care exposures, comorbid conditions, and recent infections. These claims were used to compute health care costs, which the researchers calculated as the sum of patient payments and allowable health plan expenditures.

To calculate each patients’ attributable costs, the researchers used a 2-part model. The 1st part involved logistic regression, which estimated the probability of any health care costs during the 1-year follow-up period. The 2nd part consisted of “a generalized linear model with gamma distribution and log link to model total costs among patients.” They noted that age group, sex, year, and CDI case/control indicator were included as covariates in all models to control for any residual imbalance.

The product of the fitted values from the 2-part model was the expected cost. The researchers obtained the costs attributable to CDI by subtracting the average expected costs among case patients from the average expected costs among controls.

Overall, the researchers found that costs were highest for those with HO CDI, lower for those with HCFA CDI, and lowest for those with CA CDI with costs of $48,225, $43,127, and $13,105, respectively. Additionally, they found that patients with CDI treated at a hospital accumulated substantially greater attributable costs over 1 year than those treated outside of a hospital, as their costs were $36,090 and $3063, respectively.

Despite their findings, the researchers acknowledged limitations to their study, one being their use of ICD-9 and ICD-CM-10 diagnosis codes for CDI identification, which resulted “in the potential for misclassification owing to imperfect sensitivity and specificity of administrative coding.” The researchers noted that its limitations did not take away from the study’s calculated attributable costs. Because their findings exemplify the economic burden on younger adults, the researchers emphasized the need for CDI-preventative strategies.

“Given the morbidity and excess health care costs associated with CDI, novel strategies are needed to prevent these infections in younger as well as older adults,” the authors concluded.

Reference

Sahrmann JM, Olsen MA, Keller MR, Yu H, Dubberke ER. Healthcare costs of clostridioides difficile infection in commercially insured younger adults. Open Forum Infect Dis. 2023;10(7):ofad343. doi:10.1093/ofid/ofad343