Pneumonia Hospitalization Coding Changes Associated With Transition From the 9th to 10th Revision of International Classification of Diseases

Objectives: To evaluate the impact ofInternational Classification of Disease, 10th revision, Clinical Modification (ICD-10-CM) implementation on pneumonia hospitalizations rates, which had declined following pneumococcal conjugate vaccine introduction for infants in 2000. Methods: We randomly selected records from a single hospital 1 year before (n = 500) and after (n = 500) October 2015 implementation ofICD-10-CMcoding. We used a validatedICD-9-CMalgorithm and translation of that algorithm toICD-10-CMto identify pneumonia hospitalizations pre- and post-implementation, respectively. We recodedICD-10-CMrecords toICD-9-CMand vice versa. We calculated sensitivity and positive predictive value (PPV) of theICD-10-CMalgorithm usingICD-9-CMcoding as the reference. We used sensitivity and PPV values to calculate an adjustment factor to apply toICD-10era rates to enable comparison withICD-9-CMrates. We reviewed primary diagnoses of charts not meeting the pneumonia definition when recoded. Results: Sensitivity and PPV of theICD-10-CMalgorithm were 94% and 92%, respectively, for young children and 74% and 79% for older adults. The estimated adjustment factor forICD-10-CMperiod rates was -2.09% (95% credible region [CR], -7.71% to +3.0%) for children and +6.76% (95% CR, -3.06% to +16.7%) for older adults. We identified a change in coding adult charts that met theICD-9-CMpneumonia definition that led to recoding inICD-10-CMas chronic obstructive pulmonary disease (COPD) exacerbation. Conclusions: TheICD-10-CMalgorithm derived from a validatedICD-9-CMalgorithm should not introduce substantial bias for evaluating pneumonia trends in children. However, changes in coding of pneumonia associated with COPD in adults warrant further study.