The impact of the ICD-9-CM to ICD-10-CM transition on the prevalence of birth defects among infant hospitalizations in the United States

Prevalence and Outcomes of Gastrointestinal Anomalies in Down Syndrome

OBJECTIVES

 Our objective was to investigate the prevalence of small intestinal atresia and Hirschsprung's disease (HD) in infants with Down syndrome (DS) and its impact on outcomes.

STUDY DESIGN

 We analyzed the National Inpatient Sample dataset. We included infants with DS, small intestinal atresia, HD, and the concomitant occurrence of both conditions. Regression analysis was used to control clinical and demographic variables.

RESULTS

 A total of 66,213,034 infants were included, of whom, 99,861 (0.15%) had DS. The concomitant occurrence of small intestinal atresia and HD was more frequent in infants with DS compared with the general population, adjusted odds ratio (aOR): 122, 95% confidence interval (CI): 96-154, (p < 0.001). Infants with DS and concomitant small intestinal atresia and HD had higher mortality compared with those without these conditions, aOR: 8.59, 95% CI: 1.95-37.8.

CONCLUSION

 Infants with DS are at increased risk of concomitant small intestinal atresia and HD, and this condition is associated with increased mortality.

KEY POINTS

· Infants with Down syndrome are at increased risk of congenital GI anomalies.. · Infants with Down syndrome are at increased risk of necrotizing enterocolitis.. · Increased mortality in Down syndrome infants with concomitant small intestinal atresia and Hirschsprung's disease..

Short report: Transition to International Classification of Diseases, 10th Revision and the prevalence of autism in a cohort of healthcare systems

LAY ABSTRACT

Currently, the prevalence of autism spectrum disorder (henceforth "autism") is 1 in 36, an increasing trend from previous estimates. In 2015, the United States adopted a new version (International Classification of Diseases, 10th Revision) of the World Health Organization coding system, a standard for classifying medical conditions. Our goal was to examine how the transition to this new coding system impacted autism diagnoses in 10 healthcare systems. We obtained information from electronic medical records and insurance claims data from July 2014 through December 2016 for each healthcare system. We used member enrollment data for 30 consecutive months to observe changes 15 months before and after adoption of the new coding system. Overall, the rates of autism per 1000 enrolled members was increasing for 0- to 5-year-olds before transition to International Classification of Diseases, 10th Revision and did not substantively change after the new coding was in place. There was variation observed in autism diagnoses before and after transition to International Classification of Diseases, 10th Revision for other age groups. The change to the new coding system did not meaningfully affect autism rates at the participating healthcare systems. The increase observed among 0- to 5-year-olds is likely indicative of an ongoing trend related to increases in screening for autism rather than a shift associated with the new coding.

National population-based estimates for major birth defects, 2016-2020

BACKGROUND

We provide updated crude and adjusted prevalence estimates of major birth defects in the United States for the period 2016-2020.

METHODS

Data were collected from 13 US population-based surveillance programs that used active or a combination of active and passive case ascertainment methods to collect all birth outcomes. These data were used to calculate pooled prevalence estimates and national prevalence estimates adjusted for maternal race/ethnicity for all conditions, and maternal age for trisomies and gastroschisis. Prevalence was compared to previously published national estimates from 1999 to 2014.

RESULTS

Adjusted national prevalence estimates per 10,000 live births ranged from 0.63 for common truncus to 18.65 for clubfoot. Temporal changes were observed for several birth defects, including increases in the prevalence of atrioventricular septal defect, tetralogy of Fallot, omphalocele, trisomy 18, and trisomy 21 (Down syndrome) and decreases in the prevalence of anencephaly, common truncus, transposition of the great arteries, and cleft lip with and without cleft palate.

CONCLUSION

This study provides updated national estimates of selected major birth defects in the United States. These data can be used for continued temporal monitoring of birth defects prevalence. Increases and decreases in prevalence since 1999 observed in this study warrant further investigation.

Validation of ICD-9-CM codes for major genitourinary birth defects in Military Health System administrative data, 2006-2014

BACKGROUND

The Department of Defense Birth and Infant Health Research program is dedicated to birth defects research and surveillance among military families. Here, we assess and refine the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for selected genitourinary birth defects in the Military Health System (MHS). We additionally outline methods for the calculation of positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity using a stratified sampling design.

METHODS

Among military infants born from 2006 through 2014, a random sample of ICD-9-CM screen-positive cases (for six genitourinary birth defects) and screen-negative cases were selected for chart review. PPV, NPV, sensitivity, and specificity were calculated for individual defects and any included defect (i.e., overall); measures were weighted by the inverse probability of being sampled.

RESULTS

Of 461,557 infants, 686 were sampled for chart review. Bladder exstrophy was accurately reported (PPV: >90%), while the accuracy of renal dysplasia, renal agenesis/hypoplasia, and hypospadias was moderate (PPVs: 66%-68%) and congenital hydronephrosis was low (PPV: 20%). Specificity and NPVs always exceeded 98%. The overall PPV was 50%; however, excluding congenital hydronephrosis screen-positive cases and requiring at least two inpatient or outpatient diagnostic codes resulted in a PPV of 85%.

CONCLUSIONS

The validity of major genitourinary birth defect codes varied in MHS administrative data. The accuracy of an overall defect measure improved by omitting congenital hydronephrosis and requiring at least two diagnostic codes. Although PPV is generally useful for research, additional calculation of NPV, sensitivity, and specificity better informs the identification of appropriate selection criteria across surveillance and research settings.

Pediatric Cholelithiasis in the United States: National Hospitalization Trends, 2006 to 2019

OBJECTIVES

Previous studies have shown increasing hospitalizations for pediatric cholelithiasis, but recent trends are unknown. We conducted a national study of pediatric cholelithiasis to characterize recent hospitalization rate trends.

METHODS

Retrospective repeated cross-sectional analysis of pediatric (age < 18 years) cholelithiasis-associated hospitalizations combining data from the 2006 through 2019 Kids' Inpatient Database releases. The primary outcome of interest was the national hospitalization rate (per 100,000 children). We examined rates stratified by age group and sex and characterized hospitalization outcomes and characteristics for pediatric cholelithiasis.

RESULTS

Twenty-nine thousand one hundred two hospital records representing 42,282 gallstone-associated hospitalizations were identified. The hospitalization rate declined from 12.9 [95% confidence interval (CI): 12.6-13.2] in 2006 to 9.1 (95% CI: 8.8-9.3) in 2019. Consistent with the literature, hospitalizations occurred most often among teenagers (71%) and individuals with female sex (72%). The proportion of hospitalizations at freestanding children's hospitals increased significantly (from 18.2% to 35.1%). Finally, the proportion of hospitalizations involving a potentially medical predisposing condition increased significantly.

CONCLUSIONS

The estimated US hospitalization rate for pediatric cholelithiasis declined by 30% between 2006 and 2019. Female patients and teenagers had the largest decline, and hospitalizations increasingly occurred at freestanding children's hospitals. Potential explanations include potential changes in delivery of care as well as changes in population disease burden.

Inefficiency in Delivery of General Surgery to Black Patients: A National Inpatient Sample Study

Background  Racial disparities in outcomes among patients in the United States are widely recognized, but disparities in treatment are less commonly understood. This study is intended to identify treatment disparities in delivery of surgery and time to surgery for diagnoses managed by general surgeons-appendicitis, cholecystitis, gallstone pancreatitis, abdominal wall hernias, intestinal obstructions, and viscus perforations. Methods  The National Inpatient Sample (NIS) was used to estimate and analyze disparities in delivery of surgery, type of surgery received, and timing of surgery. Age-adjusted means were compared by race/ethnicity and trends in treatment disparities were evaluated from 1993 to 2017. Linear modeling was used to measure trends in treatment and outcome disparities over time. Mediation analysis was performed to estimate contributions of all available factors to treatment differences. Relationships between treatment disparities and disparities in mortality and length of stay were similarly evaluated. Results  Black patients were less likely to receive surgery for appendicitis, cholecystitis, pancreatitis, and hernias, and more likely to receive surgery for obstructions and perforations. Black patients experienced longer wait times prior to surgery, by 0.15 to 1.9 days, depending on the diagnosis. Mediation analysis demonstrated that these disparities are not attributable to the patient factors available in the NIS, and provided some insight into potential contributors to the observed disparities, such as hospital factors and socioeconomic factors. Conclusion  Treatment disparities are present even with common indications for surgery, such as appendicitis, cholecystitis, and gallstone pancreatitis. Black patients are less likely to receive surgery with these diagnoses and must wait longer for surgery if it is performed. Surgeons should plan institution-level interventions to measure, explain, and potentially correct treatment disparities.

Accuracy of congenital anomaly coding in live birth children recorded in European health care databases, a EUROlinkCAT study

Electronic health care databases are increasingly being used to investigate the epidemiology of congenital anomalies (CAs) although there are concerns about their accuracy. The EUROlinkCAT project linked data from eleven EUROCAT registries to electronic hospital databases. The coding of CAs in electronic hospital databases was compared to the (gold standard) codes in the EUROCAT registries. For birth years 2010-2014 all linked live birth CA cases and all children identified in the hospital databases with a CA code were analysed. Registries calculated sensitivity and Positive Predictive Value (PPV) for 17 selected CAs. Pooled estimates for sensitivity and PPV were then calculated for each anomaly using random effects meta-analyses. Most registries linked more than 85% of their cases to hospital data. Gastroschisis, cleft lip with or without cleft palate and Down syndrome were recorded in hospital databases with high accuracy (sensitivity and PPV ≥ 85%). Hypoplastic left heart syndrome, spina bifida, Hirschsprung's disease, omphalocele and cleft palate showed high sensitivity (≥ 85%), but low or heterogeneous PPV, indicating that hospital data was complete but may contain false positives. The remaining anomaly subgroups in our study, showed low or heterogeneous sensitivity and PPV, indicating that the information in the hospital database was incomplete and of variable validity. Electronic health care databases cannot replace CA registries, although they can be used as an additional ascertainment source for CA registries. CA registries are still the most appropriate data source to study the epidemiology of CAs.

Investigating Tetanus, Diphtheria, Acellular Pertussis Vaccination During Pregnancy and Risk of Congenital Anomalies

INTRODUCTION

This observational retrospective matched cohort study evaluated the safety of a prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination, Boostrix. We previously reported on the risk of maternal and neonatal outcomes; here we report on the risk of congenital anomalies in infants at birth through 6 months of age.

METHODS

The study included pregnant Kaiser Permanente Southern California members. Women who received the Tdap vaccine on or after the 27th week of pregnancy between January 2018 and January 2019 were matched to women who were pregnant between January 2012 and December 2014 and were not vaccinated with Tdap during pregnancy. Unadjusted and adjusted relative risks (aRRs) with 95% confidence intervals were estimated by Poisson regression. Quantitative secular trend analyses, from 2011 to 2017, were conducted on congenital anomalies with a statistically significant aRR > 1.

RESULTS

The analysis consisted of 16,350 and 16,088 live-born infants in the Tdap-exposed and unexposed cohorts, respectively. Of the 14 congenital anomaly body systems evaluated, 8 (eye, ear/face/neck, respiratory, upper gastrointestinal, genital, renal, musculoskeletal, integument) had statistically significant elevated aRRs, with point estimates ranging from 1.17 to 2.02. The observed elevated aRRs were consistent with their respective secular increases over time.

CONCLUSION

Cautious interpretation of these findings is warranted as these increases may have resulted from improved identification and diagnosis. Furthermore, the biological plausibility of an association between maternal vaccine exposure in the third trimester of pregnancy and birth defects is low. The overall study findings support the safety of maternal immunization with Boostrix during the third trimester of pregnancy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03463577.

Systematic estimates of the global, regional and national under-5 mortality burden attributable to birth defects in 2000-2019: a summary of findings from the 2020 WHO estimates

OBJECTIVES

To examine the potential for bias in the estimate of under-5 mortality due to birth defects recently produced by the WHO and the Maternal and Child Epidemiology Estimation research group.

DESIGN

Systematic analysis.

METHODS

We examined the estimated number of under-5 deaths due to birth defects, the birth defect specific under-5 mortality rate, and the per cent of under-5 mortality due to birth defects, by geographic region, national income and under-5 mortality rate for three age groups from 2000 to 2019.

RESULTS

The under-5 deaths per 1000 live births from birth defects fell from 3.4 (95% uncertainty interval (UI) 3.1-3.8) in 2000 to 2.9 (UI 2.6-3.3) in 2019. The per cent of all under-5 mortality attributable to birth defects increased from 4.6% (UI 4.1%-5.1%) in 2000 to 7.6% (UI 6.9%-8.6%) in 2019. There is significant variability in mortality due to birth defects by national income level. In 2019, the under-5 mortality rate due to birth defects was less in high-income countries than in low-income and middle-income countries, 1.3 (UI 1.2-1.3) and 3.0 (UI 2.8-3.4) per 1000 live births, respectively. These mortality rates correspond to 27.7% (UI 26.6%-28.8%) of all under-5 mortality in high-income countries being due to birth defects, and 7.4% (UI 6.7%-8.2%) in low-income and middle-income countries.

CONCLUSIONS

While the under-5 mortality due to birth defects is declining, the per cent of under-5 mortality attributable to birth defects has increased, with significant variability across regions globally. The estimates in low-income and middle-income countries are likely underestimated due to the nature of the WHO estimates, which are based in part on verbal autopsy studies and should be taken as a minimum estimate. Given these limitations, comprehensive and systematic estimates of the mortality burden due to birth defects are needed to estimate the actual burden.

Preconception paternal comorbidities and offspring birth defects: Analysis of a large national data set

BACKGROUND

Despite the fact that the father contributes half the genome to a child, associations between paternal factors and birth defects are poorly understood.

OBJECTIVES

To investigate the association between preconception paternal health and birth defects in the offspring.

MATERIALS AND METHODS

We conducted analysis of a national cohort study utilizing the IBM Marketscan Research Database, which includes data on reimbursed private healthcare claims in the United States from 2007 to 2016. The potential association between paternal comorbidities, as measured by the components of metabolic syndrome (MetS), and any birth defect in the offspring was analyzed.

RESULTS

Of the 712,774 live births identified, 21.2% of children were born to fathers with at least one component of the metabolic syndrome (MetS ≥1) prior to conception. Compared to infants born to fathers with no components of the metabolic syndrome, a modestly higher percentage of infants with cardiac birth defects were born to fathers with more components of MetS (MetS = 1, OR [95% CI]: 1.07 [1.01-1.13]; MetS ≥2, 1.17 [1.08-1.26], in comparison to MetS = 0) after adjusting for maternal and paternal factors. Similarly, a higher percentage of infants with respiratory defects were born to fathers with two or more components of metabolic syndrome (MetS ≥2, OR [95% CI]: 1.45 [1.22-1.71]).

DISCUSSION AND CONCLUSION

In this private insurance claims-based study, we found that fathers with metabolic syndrome-related diseases before conception were at increased risk for having a child affected by birth defects, especially cardiac and respiratory defects, and this association was not influenced by paternal age or assessed maternal factors.

A population-based descriptive study of neonatal abstinence syndrome using hospital discharge and birth certificate data

BACKGROUND

Neonatal abstinence syndrome (NAS), largely a consequence of prenatal opioid exposure, results in substantial morbidity. Population-based studies of NAS going beyond Medicaid populations and hospital discharge data (HDD) alone are limited. Using statewide Tennessee (TN) HDD and birth certificate (BC) data, we examined trends and evaluated maternal and infant factors associated with NAS.

METHODS

We conducted a population-based descriptive study during 2013-2017 in TN. NAS infants were identified with International Classification of Diseases (ICD)-9-Clinical Modification (CM) and ICD-10-CM codes in HDD and linked to BC data using iterative deterministic matching algorithms. Descriptive analyses were conducted for infant and maternal factors (exposures) by NAS (outcome). Multivariable logistic regression models were used to estimate adjusted ORs and 95% CIs.

RESULTS

NAS incidence increased from 13.4 to 15.4 per 1,000 live births between 2013-2017 (15% increase; ptrend<0.001), but remained stable in 2017. In adjusted models, maternal factors associated with reduced odds of NAS included breastfeeding (OR:0.55, 95%CI:0.52-0.59) and prenatal care (OR:0.36, 95%CI:0.32-0.41). Smoking, preterm birth and lower birthweight were associated with increased odds of NAS.

CONCLUSIONS

This study highlights the value of utilizing surveillance data to monitor trends and correlates of NAS to inform prevention efforts and targeting of public health resources.

Development and Validation of a Functionally Relevant Comorbid Health Index in Adults Admitted to Inpatient Rehabilitation for Traumatic Brain Injury

Several studies have characterized comorbidities among individuals with traumatic brain injury (TBI); however, there are few validated TBI comorbidity indices. Widely used indices (e.g., Elixhauser Comorbidity Index [ECI]) were developed in other patient populations and anchor to mortality or healthcare utilization, not functioning, and notably exclude conditions known to co-occur with TBI. The objectives of this study were to develop and validate a functionally relevant TBI comorbidity index (Fx-TBI-CI) and to compare prognostication of the Fx-TBI-CI with the ECI. We used data from the eRehabData database to divide the sample randomly into a training sample (N = 21,292) and an internal validation sample (N = 9166). We used data from the TBI Model Systems National Database as an external validation sample (N = 1925). We used least absolute shrinkage and selection operator (LASSO) regression to narrow the list of functionally relevant conditions from 39 to 12. In internal validation, the Fx-TBI-CI explained 14.1% incremental variance over an age and sex model predicting the Functional Independence Measure (FIM) Motor subscale at inpatient rehabilitation discharge, compared with 2.4% explained by the ECI. In external validation, the Fx-TBI-CI explained 4.9% incremental variance over age and sex and 3.8% over age, sex, and Glasgow Coma Scale score,compared with 2.1% and 1.6% incremental variance, respectively, explained by the ECI. An unweighted Sum Condition Score including the same conditions as the Fx-TBI-CI conferred similar prognostication. Although the Fx-TBI-CI had only modest incremental variance over demographics and injury severity in predicting functioning in external validation, the Fx-TBI-CI outperformed the ECI in predicting post-TBI function.

Impact of the ICD-9-CM to ICD-10-CM transition on the incidence of severe maternal morbidity among delivery hospitalizations in the United States

BACKGROUND

Surveillance of maternal mortality and severe maternal morbidity is important to identify temporal trends, evaluate the impact of clinical practice changes or interventions, and monitor quality of care. A common source for severe maternal morbidity surveillance is hospital discharge data. On October 1, 2015, all hospitals in the United States transitioned from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding for diagnoses and procedures.

OBJECTIVE

This study aimed to evaluate the impact of the transition from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding systems on the incidence of severe maternal morbidity in the United States in hospital discharge data.

STUDY DESIGN

Using data from the National Inpatient Sample, obstetrical deliveries between January 1, 2012, and December 31, 2017, were identified using a validated case definition. Severe maternal morbidity was defined using the International Classification of Diseases, Ninth Revision, Clinical Modification (January 1, 2012, to September 30, 2015) and the International Classification of Diseases, Tenth Revision, Clinical Modification (October 1, 2015, to December 31, 2017) codes provided by the Centers for Disease Control and Prevention. An interrupted time series and segmented regression analysis was used to assess the impact of the transition from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding on the incidence of severe maternal morbidity per 1000 obstetrical deliveries.

RESULTS

From 22,751,941 deliveries, the incidence of severe maternal morbidity in the International Classification of Diseases, Ninth Revision, Clinical Modification coding era was 19.04 per 1000 obstetrical deliveries and decreased to 17.39 per 1000 obstetrical deliveries in the International Classification of Diseases, Tenth Revision, Clinical Modification coding era (P<.001). The transition to International Classification of Diseases, Tenth Revision, Clinical Modification coding led to an immediate decrease in the incidence of severe maternal morbidity (-2.26 cases of 1000 obstetrical deliveries) (P<.001). When blood products transfusion was removed from the case definition, the magnitude of the decrease in the incidence of SMM was much smaller (-0.60 cases/1000 obstetric deliveries), but still significant (P<.001).

CONCLUSION

After the transition to the International Classification of Diseases, Tenth Revision, Clinical Modification coding for health diagnoses and procedures in the United States, there was an abrupt statistically significant and clinically meaningful decrease in the incidence of severe maternal morbidity in hospital discharge data. Changes in the underlying health of the obstetrical population are unlikely to explain the sudden change in severe maternal morbidity. Although much work has been done to validate the International Classification of Diseases, Ninth Revision, Clinical Modification codes for severe maternal morbidity, it is critical that validation studies be undertaken to validate the International Classification of Diseases, Tenth Revision, Clinical Modification codes for severe maternal morbidity to permit ongoing surveillance, quality improvement, and research activities that rely on hospital discharge data.

Neonatal Abstinence Syndrome and Maternal Opioid-Related Diagnoses: Analysis of ICD-10-CM Transition, 2013-2017

BACKGROUND AND OBJECTIVES

Hospital discharge records remain a common data source for tracking the opioid crisis among pregnant women and infants. The International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) transition from the International Classification of Diseases, Ninth Revision, Clinical Modification may have affected surveillance. Our aim was to evaluate this transition on rates of neonatal abstinence syndrome (NAS), maternal opioid use disorder (OUD), and opioid-related diagnoses (OUD with ICD-10-CM codes for long-term use of opioid analgesics and unspecified opioid use).

METHODS

Data from the 2013-2017 Healthcare Cost and Utilization Project's National Inpatient Sample were used to conduct, interrupted time series analysis and log-binomial segmented regression to assess whether quarterly rates differed across the transition.

RESULTS

From 2013 to 2017, an estimated 18.8 million birth and delivery hospitalizations were represented. The ICD-10-CM transition was not associated with NAS rates (rate ratio [RR]: 0.99; 95% confidence interval [CI]: 0.90-1.08; P = .79) but was associated with 11% lower OUD rates (RR: 0.89; 95% CI: 0.80-0.98; P = .02) and a decrease in the quarterly trend (RR: 0.98; 95% CI: 0.96-1.00; P = .04). The transition was not associated with maternal OUD plus long-term use rates (RR: 0.98; 95% CI: 0.89-1.09; P = .76) but was associated with a 20% overall increase in opioid-related diagnosis rates including long-term and unspecified use (RR: 1.20; 95% CI: 1.09-1.32; P < .001).

CONCLUSIONS

The ICD-10-CM transition did not appear to affect NAS. However, coding of maternal OUD alone may not capture the same population across the transition, which confounds the interpretation of trend data spanning this time period.

The Impact of Transitioning From International Classification of Diseases, Ninth Revision to International Classification of Diseases, Tenth Revision on Reported Complication Rates Following Primary Total Knee Arthroplasty

BACKGROUND

In 2015, the healthcare system transitioned from International Classification of Diseases, Ninth Revision (ICD-9) coding to the Tenth Revision (ICD-10). We sought to determine the effect of this change on the reported incidence of complications following total knee arthroplasty (TKA).

METHODS

The Humana administrative claims database was queried from 2 years prior to October 1, 2015 (ICD-9 cohort) and for 1 year after this date (ICD-10 cohort) to identify all TKA procedures. Complications occurring within 6 months of surgery were captured using the respective coding systems. Incidence of each complication was compared between cohorts using risk ratios (RR) and 95% confidence intervals.

RESULTS

There were 19,009 TKAs in the ICD-10 cohort and 38,172 TKAs in the ICD-9 cohort. The incidence of each complication analyzed was significantly higher in the ICD-9 cohort relative to the ICD-10 cohort. Periprosthetic joint infection occurred in 1.9% vs 1.3% (RR 1.5, 1.3-1.9), loosening in 0.3% vs 0.1% (RR 2.7, 1.8-4.9), periprosthetic fracture in 0.3% vs 0.1% (RR 3.0, 1.6-4.5), and other mechanical complications in 0.7% vs 0.4% (RR 2.0, 1.5-2.5) (P < .05 for all).

CONCLUSION

The transition from ICD-9 to ICD-10 coding has altered the reported incidence of complications following TKA. These results are likely due to the added complexity of ICD-10 which is joint and laterality specific. It is important to understand the differences between coding systems as this data is used for quality initiatives, risk adjustment models, and clinical research. Thoughtful methodology will be necessary when ICD-9 and ICD-10 data are being analyzed simultaneously.

Impact of ICD-9-CM to ICD-10-CM coding transition on trauma hospitalization trends among young adults in 12 states

BACKGROUND

We aimed to estimate the impact of the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) coding transition on traumatic injury-related hospitalization trends among young adults across a geographically and demographically diverse group of U.S. states.

METHODS

Interrupted time series analyses were conducted using statewide inpatient databases from 12 states and including traumatic injury-related hospitalizations in adults aged 19-44 years in 2011-2017. Segmented regression models were used to estimate the impact of the October 2015 coding transition on external cause of injury (ECOI) completeness (percentage of hospitalizations with a documented ECOI code) and on population-level rates of injury-related hospitalizations by nature, intent, mechanism, and severity of injury.

RESULTS

The transition to ICD-10-CM was associated with a drop in ECOI completion in the transition month (- 3.7%; P < .0001), but there was no significant change in the positive trend in ECOI completion from the pre- to post-transition periods. There were significant increases post-transition in the measured rates of hospitalization for traumatic brain injury (TBI), unintentional injury, mild injury (injury severity score (ISS) < 9), and injuries caused by drowning, firearms, machinery, other pedestrian, suffocation, and unspecified mechanism. Conversely, there were significant decreases in October 2015 in the rates of hospitalization for assault, injuries of undetermined intent, injuries of moderate severity (ISS 9-15), and injuries caused by fire/burn, other pedal cyclist, other transportation, natural/environmental, and other specified mechanism. A significant increase in the percentage of hospitalizations classified as resulting from severe injury (ISS > 15) was observed when the general equivalence mapping maximum severity method for converting ICD-10-CM codes to ICD-9-CM codes was used. State-specific results for the outcomes of ECOI completion and TBI-related hospitalization rates are provided in an online supplement.

CONCLUSIONS

The U.S. transition from ICD-9-CM to ICD-10-CM coding led to a significant decrease in ECOI completion and several significant changes in measured rates of injury-related hospitalizations by injury intent, mechanism, nature, and severity. The results of this study can inform the design and analysis of future traumatic injury-related health services research studies that use both ICD-9-CM and ICD-10-CM coded data.

LEVEL OF EVIDENCE

II (Interrupted Time Series).