Identifying pediatric community-acquired pneumonia hospitalizations: Accuracy of administrative billing codes

Abstract

Importance: Community-acquired pneumonia (CAP) remains one of the most common indications for pediatric hospitalization in the United States, and it is frequently the focus of research and quality studies. Use of administrative data is increasingly common for these purposes, although proper validation is required to ensure valid study conclusions.

Objective: To validate administrative billing data for hospitalizations owing to childhood CAP.

Design and setting: Case-control study of 4 tertiary care, freestanding children’s hospitals in the United States.

Participants: A total of 998 medical records of a 25% random sample of 3646 children discharged in 2010 with at least 1 International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code representing possible pneumonia were reviewed. Discharges (matched on date of admission) without a pneumonia-related discharge code were also examined to identify potential missed pneumonia cases. Two reference standards, based on provider diagnosis alone (provider confirmed) or in combination with consistent clinical and radiographic evidence of pneumonia (definite), were used to identify CAP.

Exposure: Twelve ICD-9-CM–based coding strategies, each using a combination of primary or secondary codes representing pneumonia or pneumonia-related complications. Six algorithms excluded children with complex chronic conditions.

Main outcomes and measures: Sensitivity, specificity, and negative and positive predictive values (NPV and PPV, respectively) of the 12 identification strategies.

Results: For provider-confirmed CAP (n = 680), sensitivity ranged from 60.7% to 99.7%; specificity, 75.7% to 96.4%; PPV, 67.9% to 89.6%; and NPV, 82.6% to 99.8%. For definite CAP (n = 547), sensitivity ranged from 65.6% to 99.6%; specificity, 68.7% to 93.0%; PPV, 54.6% to 77.9%; and NPV, 87.8% to 99.8%. Unrestricted use of the pneumonia-related codes was inaccurate, although several strategies improved specificity to more than 90% with a variable effect on sensitivity. Excluding children with complex chronic conditions demonstrated the most favorable performance characteristics. Performance of the algorithms was similar across institutions.

Conclusions and relevance: Administrative data are valuable for studying pediatric CAP hospitalizations. The strategies presented here will aid in the accurate identification of relevant and comparable patient populations for research and performance improvement studies.

Figure 1

Study population

Figure 2

Sensitivity and specificity of twelve ICD-9-CM code identification algorithms for community-acquired pneumonia (CAP) using two reference standards: (a) Provider-confirmed CAP (n=680); (b) Definite CAP (n=547). Horizontal and vertical bars represent calculated 95% confidence limits. Algorithm definitions, 1: 1° or any 2° diagnosis of pneumonia or effusion/empyema (1b excludes complex chronic conditions [CCCs]—see reference 20); 2: 1° diagnosis of pneumonia or effusion/empyema (2b excludes CCCs); 3: 1° diagnosis of pneumonia or effusion/empyema OR 1° diagnosis of pneumonia-related complication PLUS any 2° diagnosis of pneumonia or effusion/empyema (3b excludes CCCs); 4: 1° or any 2° diagnosis of pneumonia (4b excludes CCCs); 5: 1° diagnosis of pneumonia (5b excludes CCCs); 6: 1° diagnosis of pneumonia OR 1° diagnosis of pneumonia-related complication or effusion/empyema PLUS any 2° diagnosis of pneumonia (6b excludes CCCs); ICD-9-CM codes used in the study are as follows, pneumonia: 480.0-2, 480.8-9, 481, 482.0, 482.30-2, 482.41-2, 482.83, 482.89-90, 483.8, 484.3, 485, 486, 487.0; effusion/empyema: 510.0, 510.9, 511.0-1, 511.8-9, 513; pneumonia-related complication: 38.9, 458.9, 518.81, 790.7, 799.1, 995.91-2, 997.3.

Figure 2

Sensitivity and specificity of twelve ICD-9-CM code identification algorithms for community-acquired pneumonia (CAP) using two reference standards: (a) Provider-confirmed CAP (n=680); (b) Definite CAP (n=547). Horizontal and vertical bars represent calculated 95% confidence limits. Algorithm definitions, 1: 1° or any 2° diagnosis of pneumonia or effusion/empyema (1b excludes complex chronic conditions [CCCs]—see reference 20); 2: 1° diagnosis of pneumonia or effusion/empyema (2b excludes CCCs); 3: 1° diagnosis of pneumonia or effusion/empyema OR 1° diagnosis of pneumonia-related complication PLUS any 2° diagnosis of pneumonia or effusion/empyema (3b excludes CCCs); 4: 1° or any 2° diagnosis of pneumonia (4b excludes CCCs); 5: 1° diagnosis of pneumonia (5b excludes CCCs); 6: 1° diagnosis of pneumonia OR 1° diagnosis of pneumonia-related complication or effusion/empyema PLUS any 2° diagnosis of pneumonia (6b excludes CCCs); ICD-9-CM codes used in the study are as follows, pneumonia: 480.0-2, 480.8-9, 481, 482.0, 482.30-2, 482.41-2, 482.83, 482.89-90, 483.8, 484.3, 485, 486, 487.0; effusion/empyema: 510.0, 510.9, 511.0-1, 511.8-9, 513; pneumonia-related complication: 38.9, 458.9, 518.81, 790.7, 799.1, 995.91-2, 997.3.