Evaluation of Complication Rates after Coronary Artery Bypass Surgery using Administrative Data

The predictability of claim-data-based comorbidity-adjusted models could be improved by using medication data

Background

Recently, claim-data-based comorbidity-adjusted methods such as the Charlson index and the Elixhauser comorbidity measures have been widely used among researchers. At the same time, there have been an increasing number of attempts to improve the predictability of comorbidity-adjusted models. We tried to improve the predictability of models using the Charlson and Elixhauser indices by using medication data; specifically, we used medication data to estimate omitted comorbidities in the claim data.

Methods

We selected twelve major diseases (other than malignancies) that caused large numbers of in-hospital mortalities during 2008 in hospitals with 700 or more beds in South Korea. Then, we constructed prediction models for in-hospital mortality using the Charlson index and Elixhauser comorbidity measures, respectively. Inferring missed comorbidities using medication data, we built enhanced Charlson and Elixhauser comorbidity-measures-based prediction models, which included comorbidities inferred from medication data. We then compared the c-statistics of each model.

Results

247,712 admission cases were enrolled. 55 generic drugs were used to infer 8 out of 17 Charlson comorbidities, and 106 generic drugs were used to infer 14 out of 31 Elixhauser comorbidities. Before the inclusion of comorbidities inferred from medication data, the c-statistics of models using the Charlson index were 0.633-0.882 and those of the Elixhauser index were 0.699-0.917. After the inclusion of comorbidities inferred from medication data, 9 of 12 models using the Charlson index and all of the models using the Elixhauser comorbidity measures were improved in predictability but, the differences were relatively small.

Conclusion

Prediction models using Charlson index or Elixhauser comorbidity measures might be improved by including comorbidities inferred from medication data.

Gender differences in clinical outcomes among diabetic patients hospitalized for cardiovascular disease

BACKGROUND

The risk of incident cardiovascular disease (CVD) has been shown to be greater among diabetic women than men, but gender differences in clinical outcomes among diabetic patients hospitalized with CVD are not established. We aimed to determine if hemoglobin A1c (HbA1c) was associated with 30-day and 1-year CVD rehospitalization and total mortality among diabetic patients hospitalized for CVD, overall and by gender.

METHODS

This was a prospective analysis of diabetic patients hospitalized for CVD, enrolled in an National Heart, Lung and Blood Institute-sponsored observational clinical outcomes study (N = 902, 39% female, 53% racial/ethnic minority, mean age 67 ± 12 years). Laboratory, rehospitalization, and mortality data were determined by hospital-based electronic medical record. Poor glycemic control was defined as HbA1c ≥7%. The association between HbA1c and clinical outcomes was evaluated using logistic regression; gender modification was evaluated by interaction terms and stratified models.

RESULTS

Hemoglobin A1c ≥7% prevalence was 63% (n = 566) and was similar by gender. Hemoglobin A1c ≥7% vs <7% was associated with increased 30-day CVD rehospitalization in univariate (odds ratio [OR] = 1.63, 95% CI 1.05-2.54) and multivariable-adjusted models (OR 1.74, 95% CI 1.06-2.84). There was an interaction between glycemic control and gender for 30-day CVD rehospitalization risk (P = .005). In stratified univariate models, the association was significant among women (OR 4.83, 95% CI 1.84-12.71) but not among men (OR 1.02, 95% CI 0.60-1.71). The multivariate-adjusted risk for HbA1c ≥7% versus <7% among women was 8.50 (95% CI 2.31-31.27) and 1.02 (95% CI 0.57-1.80) for men. A trend toward increased 30-day/1-year mortality risk was observed for HbA1c <6% vs ≥6% for men and women.

CONCLUSIONS

Risk of 30-day CVD rehospitalization was 8.5-fold higher among diabetic women hospitalized for CVD with HbA1c ≥7% vs <7%; no association was observed among men. A trend for increased 30-day/1-year mortality risk with HbA1c <6% deserves further study.

Association between having a caregiver and clinical outcomes 1 year after hospitalization for cardiovascular disease

Caregivers might represent an opportunity to improve cardiovascular disease outcomes, but prospective data are limited. We studied 3,188 consecutive patients (41% minority, 39% women) admitted to a university hospital medical cardiovascular service to evaluate the association between having a caregiver and rehospitalization/death at 1 year. The clinical outcomes at 1 year were documented using a hospital-based clinical information system supplemented by a standardized questionnaire. Co-morbidities were documented by hospital electronic record review. At baseline, 13% (n = 417) of the patients had a paid caregiver and 25% (n = 789) had only an informal caregiver. Having a caregiver was associated with rehospitalization or death at 1 year (odds ratio [OR] 1.68, 95% confidence interval [CI] 1.45 to 1.95), which varied by paid (OR 2.46, 95% CI 1.96 to 3.09) and informal (OR 1.40, 95% CI 1.18 to 1.65) caregiver status. Having a caregiver was significantly (p <0.05) associated with age ≥65 years, racial/ethnic minority, lack of health insurance, medical history of diabetes mellitus or hypertension, a Ghali co-morbidity index >1, chronic obstructive pulmonary disease, or taking ≥9 prescriptions medications. The relation between caregiving and rehospitalization/death at 1 year was attenuated but remained significant after adjustment (paid, OR 1.64, 95% CI 1.26 to 2.12; and informal, OR 1.20, 95% CI 1.00 to 1.44). In conclusion, the risk of rehospitalization/death was significantly greater among cardiac patients with caregivers and was not fully explained by the presence of traditional co-morbidities. Systematic determination of having a caregiver might be a simple method to identify patients at a heightened risk of poor clinical outcomes.

Maximising the value of hospital administrative datasets

Mandatory and standardised administrative data collections are prevalent in the largely public-funded acute sector. In these systems the data collections are used for financial, performance monitoring and reporting purposes. This paper comments on the infrastructure and standards that have been established to support data collection activities, audit and feedback. The routine, local and research uses of these datasets are described using examples from Australian and international literature. The advantages of hospital administrative datasets and opportunities for improvement are discussed under the following headings: accessibility, standardisation, coverage, completeness, cost of obtaining clinical data, recorded Diagnostic Related Groups and International Classification of Diseases codes, linkage and connectivity. In an era of diminishing resources better utilisation of these datasets should be encouraged. Increased study and scrutiny will enhance transparency and help identify issues in the collections. As electronic information systems are increasingly embraced, administrative data collections need to be managed as valuable assets and powerful operational and patient management tools.

Impact of surgeon training on outcomes after resective hepatic surgery

BACKGROUND

Higher hospital and surgeon volumes have been associated with improved outcomes after hepatic resection. Subspecialty training has not previously been associated with improved outcomes after hepatic resection. The objective of this study was to determine what effects, if any, surgeon's volume and training had on the outcomes after hepatic resection.

METHODS

Administrative procedure codes were used to identify all adult patients from the fiscal year 1991-1992 to 2003-2004 who underwent a hepatic resection in two large urban health regions in Canada (Calgary and Capital health regions). The primary outcomes were operative mortality and postoperative complications.

RESULTS

There were 1107 hepatic resections in the stated time period performed by a total of 72 surgeons. There were 66 deaths, resulting in an in-hospital mortality rate of 6.0%, and an overall complication rate of 46%. Statistically significant predictors of operative mortality were: urgency of admission, diagnosis of primary hepatic malignancy, extent of resection, and increasing burden of comorbid medical illness. Surgeon training along with patient's sex, the urgency of admission, diagnosis of primary hepatic malignancy, extent of resection, and increasing comorbidity were predictive of postoperative complications.

CONCLUSIONS

This study found surgeon training to be highly predictive of postoperative complications after hepatic resection.

Limitations of Hospital Volume as a Measure of Quality of Care for Coronary Artery Bypass Graft Surgery

BACKGROUND

While prior research has found an inverse relationship between hospital volume and mortality after coronary artery bypass graft surgery (CABG), the use of volume as a proxy for quality and a means for selecting hospitals is controversial. The objective of this study is to quantify the relationship between hospital volume alone and CABG mortality.

METHODS

A retrospective cohort of 948,093 Medicare patients undergoing CABG in 870 US hospitals from 1996 to 2001 was categorized into quintiles, based on hospital CABG volume. Hospitals were also classified by volume criterion proposed by the Leapfrog Group. Logistic regression was used to adjust hospital mortality rates (in-hospital or within 30 days after CABG) for patient characteristics; discrimination of the volume categories was assessed by the c statistic.

RESULTS

The range in risk-adjusted mortality for hospitals within the quintiles was substantial: 1% to 17% at very low, 2% to 12% at low, 2% to 10% at medium, 2% to 9% at high, and 3% to 11% at very high volume hospitals. Moreover, volume alone was a poor discriminator of mortality (c statistic = 0.52). Similar variation in adjusted mortality was seen within the Leapfrog low-volume (1% to 17%) and high-volume groups (2% to 11%), and the Leapfrog criterion was a poor discriminator of mortality (c statistic = 0.51). Of the 660 low-volume Leapfrog hospitals, 253 (38%) had risk-adjusted mortality rates that were similar to or lower than the overall risk-adjusted mortality of high-volume hospitals (5.2%).

CONCLUSIONS

Volume alone, as a discriminator of mortality, is only slightly better than a coin flip (c statistic of 0.50).

Can administrative data be used to compare postoperative complication rates across hospitals?

BACKGROUND

Several quality assessment systems use administrative data to identify postoperative complications, with uncertain validity.

OBJECTIVES

To determine how accurately postoperative complications are reported in administrative data, whether accuracy varies systematically across hospitals, and whether serious complications are more consistently reported.

DESIGN

Retrospective cohort.

SUBJECTS

Nine hundred ninety-one randomly sampled adults who underwent elective lumbar diskectomies at 30 nonfederal acute care hospitals in California in 1990 to 1991. Hospitals with especially low or high risk-adjusted complication rates, and patients who experienced complications, were over sampled.

MEASURES

Postoperative complications were specified by reviewing medical literature and consulting clinical experts; each complication was mapped to ICD-9-CM. Hospital-reported complications were compared with our independent recoding of the same records.

RESULTS

The weighted sensitivity, specificity, and positive and negative predictive values for reported complications were 35%, 98%, 82%, and 84%, respectively. The weighted sensitivity was 30% for serious, 40% for minor, and 10% for questionable complications. It varied from 21% among hospitals with fewer complications than expected to 45% among hospitals with more complications than expected. Only reoperation, bacteremia/sepsis, postoperative infection, and deep vein thrombosis were reported with at least 60% sensitivity. Half of the difference in risk-adjusted complication rates between low and high outlier hospitals was attributable to reporting variation.

CONCLUSIONS

ICD-9-CM complications were underreported among diskectomy patients, especially at hospitals with low risk-adjusted complication rates. The validity of using coded complications to compare provider performance is questionable, even with careful efforts to identify serious events, although these results must be confirmed using more recent data.

Can administrative data be used to ascertain clinically significant postoperative complications?

The purpose of this study is to assess whether postoperative complications can be ascertained using administrative data. We randomly sampled 991 adults who underwent elective open diskectomies at 30 nonfederal acute care hospitals in California. Postoperative complications were specified by reviewing medical literature and by consulting clinical experts. We compared hospital-reported ICD-9-CM data and independently recoded ICD-9-CM data with complications abstracted by clinicians using detailed criteria. Recoded ICD-9-CM data were more likely than hospital-reported ICD-9-CM data to capture true complications, when they occurred, but they also mislabeled more patients who never experienced clinically significant complications. This finding was most evident for mild or ambiguous complications, such as atelectasis, posthemorrhagic anemia, and hypotension. Overall, recoded ICD-9-CM data captured 47% and 56% of all mild and severe complications, respectively, whereas hospital-reported ICD-9-CM data captured only 37% and 44%, respectively, of all mild and severe complications. These findings raise questions about the validity of using administrative data to ascertain postoperative complications, even if coders are carefully hired, trained, and supervised. ICD-9-CM complication codes are more promising as a tool to help providers identify their own adverse outcomes than as a tool for comparing performance.

Trends in utilization of coronary artery bypass surgery and associated outcomes: Alberta, Manitoba, and Nova Scotia

The primary objective of this study was to examine trends in rates and outcomes of coronary artery bypass graft (CABG) surgery across the 3 Canadian provinces of Alberta, Manitoba, and Nova Scotia, during fiscal years 1991-1995. Annual age-standardized CABG surgery rates were calculated by sex for each province. Province-specific average length of stay (ALOS) and postsurgical complication rates were calculated using ICD-9 codes. Rates of CABG were higher among men compared with women in all 3 provinces. Whereas ALOS, complications rates, and mortality rates decreased in all provinces over the study period, there was considerable variation in province-specific rates.

Identifying patient preoperative risk factors and postoperative adverse events in administrative databases: results from the Department of Veterans Affairs National Surgical Quality Improvement Program

BACKGROUND

The Department of Veterans Affairs (DVA) National Surgical Quality Improvement Program (NSQIP) employs trained nurse data collectors to prospectively gather preoperative patient characteristics and 30-day postoperative outcomes for most major operations in 123 DVA hospitals to provide risk-adjusted outcomes to centers as quality indicators. It has been suggested that routine hospital discharge abstracts contain the same information and would provide accurate and complete data at much lower cost.

STUDY DESIGN

With preoperative risks and 30-day outcomes recorded by trained data collectors as criteria standards, ICD-9-CM hospital discharge diagnosis codes in the Patient Treatment File (PTF) were tested for sensitivity and positive predictive value. ICD-9-CM codes for 61 preoperative patient characteristics and 21 postoperative adverse events were identified.

RESULTS

Moderately good ICD-9-CM matches of descriptions were found for 37 NSQIP preoperative patient characteristics (61%); good data were available from other automated sources for another 15 (25%). ICD-9-CM coding was available for only 13 (45%) of the top 29 predictor variables. In only three (23%) was sensitivity and in only four (31%) was positive predictive value greater than 0.500. There were ICD-9-CM matches for all 21 NSQIP postoperative adverse events; multiple matches were appropriate for most. Postoperative occurrence was implied in only 41%; same breadth of clinical description in only 23%. In only four (7%) was sensitivity and only two (4%) was positive predictive value greater than 0.500.

CONCLUSION

Sensitivity and positive predictive value of administrative data in comparison to NSQIP data were poor. We cannot recommend substitution of administrative data for NSQIP data methods.

Computerized assessment of complications after colorectal surgery: is it valid?

PURPOSE

Historically, complication rates after colorectal surgery have been stratified by disease process, type of operation, or anesthesia risk derived after an intensive review of the medical record. Newer computer applications purport to shorten this process and predict the probability of postoperative complications by distinguishing them from comorbidities that are commingled on uniform discharge codes. We analyzed CaduCIS software, which uses discharge codes, to determine whether its predictions of comorbidity and complications were comparable to what was interpreted on the medical record.

METHODS

Two-hundred seventy patients were analyzed according to the principal and secondary diagnoses coded on discharge. Coding inaccuracies of clinical occurrences were identified by physician review of each medical record. The actual incidences of 17 common preoperative comorbidities and 11 postoperative complications were compared with those predicted by CaduCIS.

RESULTS

The CaduCIS-predicted distribution of comorbidities was similar to the actual occurrences in 15 of 17 categories. The overall incidence of complications obtained by physician (actual) review was 47 percent, compared with 46 percent predicted by CaduCIS. However, there was a statistical difference between the CaduCIS-predicted and the actual complication rates in 5 of the 11 categories. The most common preoperative comorbidity and complication was cardiopulmonary (47 percent and 28 percent, respectively).

CONCLUSION

The overall complication rate interpreted from the medical record (47 percent) was accurately predicted by CaduCIS (46 percent). Predictions of 5 of 11 individual complications were underestimated because of charting and coding inaccuracies, not because of computerized errors. Because uniform discharge coding of commingled comorbidity and complications is increasingly used to rapidly compute surgical outcomes, colon and rectal surgeons need to ensure compatibility of the actual and coded medical records.

Coronary artery bypass graft surgery: socioeconomic inequalities in access and in 30 day mortality. A population-based study in Rome, Italy

OBJECTIVES

To evaluate whether coronary artery bypass graft (CABG) surgery is equally provided among different socioeconomic status (SES) groups in accordance with need. To estimate the association between SES and mortality occurring 30 days after CABG surgery.

DESIGN

Individual socioeconomic index assigned with respect to the characteristics of the census tract of residence (level I = highest SES; level IV = lowest SES). Comparison of age adjusted hospital admission rates of ischaemic heart disease (IHD) and CABG surgery among four SES groups. Retrospective cohort study of all patients who underwent CABG surgery during 1996-97.

SETTING

Rome (2 685 890 inhabitants) and the seven cardiac surgery units in the city.

PARTICIPANTS

All residents in Rome aged 35 years or more. A cohort of 1875 CABG patients aged 35 years or more.

MAIN OUTCOME MEASURES

Age adjusted hospitalisation rates for CABG and IHD and rate of CABG per 100 IHD hospitalisations by SES group, taking level I as the reference group. Odds ratios of 30 day mortality after CABG surgery, adjusted for age, gender, illness severity at admission, and type of hospital where CABG was performed.

RESULTS

People in the lowest SES level experienced an excess in the age adjusted IHD hospitalisation rates compared with the highest SES level (an excess of 57% among men, and of 94% among women), but the rate of CABG per 100 IHD hospitalisations was lower, among men, in the most socially disadvantaged level (8.9 CABG procedures per 100 IHD hospital admissions in level IV versus 14.1 in level I rate ratio= 0.63; 95% CI 0.44, 0.89). The most socially disadvantaged SES group experienced a higher risk of 30 day mortality after CABG surgery (8. 1%) than those in the highest SES group (4.8%); this excess in mortality was confirmed even when initial illness severity was taken into account (odds ratio= 2.89; 95% CI 1.44, 5.80).

CONCLUSIONS

The universal coverage of the National Health Service in Italy does not guarantee equitable access to CABG surgery for IHD patients. Factors related to SES are likely to influence poor prognosis after CABG surgery.