Patricia A. Zrelak

Evaluation of the predictive value of ICD-9-CM coded administrative data for venous thromboembolism in the United States

OBJECTIVE To determine the positive predictive value of International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) discharge codes for acute deep vein thrombosis or pulmonary embolism. MATERIALS AND METHODS Retrospective review of 3456 cases hospitalized between 2005 and 2007 that had a discharge code for venous thromboembolism, using 3 sample populations: a single academic hospital, 33 University HealthSystem Consortium hospitals, and 35 community hospitals in a national Joint Commission study. Analysis was stratified by position of the code in the principal versus a secondary position. RESULTS Among 1096 cases that had a thromboembolism code in the principal position the positive predictive value for any acute venous thrombosis was 95% (95%CI:93-97), whereas among 2360 cases that had a thromboembolism code in a secondary position the predictive value was lower, 75% (95%CI:71-80). The corresponding positive predictive values for lower extremity deep-vein thrombosis or pulmonary embolism were 91% (95%CI:86-95) and 50% (95%CI:41-58), respectively. More highly defined codes had higher predictive value. Among codes in a secondary position that were false positive, 22% (95%CI:16-27) had chronic/prior venous thrombosis, 15% (95%CI:10-19) had an upper extremity thrombosis, 6% (95%CI:4-8) had a superficial vein thrombosis, and 7% (95%CI:4-13) had no mention of any thrombosis. CONCLUSIONS ICD-9-CM codes for venous thromboembolism had high predictive value when present in the principal position, and lower predictive value when in a secondary position. New thromboembolism codes that were added in 2009 that specify chronic thrombosis, upper extremity thrombosis and superficial venous thrombosis should reduce the frequency of false-positive thromboembolism codes.

Brain structure and cognition in a community sample of elderly Latinos

BackgroundPrevious studies have found that hippocampal atrophy and white matter hyperintensities (WMH) on MRI are linked to cognitive impairment and dementia. The authors measured these variables in a population-based cohort of older Mexican Americans with a wide spectrum of cognitive ability, ranging from normal cognition to dementia. ObjectiveTo investigate whether these structural brain changes were seen in individuals prior to the development of dementia and how these changes were related to the presence of dementia. MethodsA sample of 122 subjects was selected from the Sacramento Area Latino Study on Aging, and subjects were categorized into four groups of increasing levels of cognitive impairment: normal, memory impaired (MI), cognitively impaired but not demented (CIND), and demented. Hippocampal volume was quantified using a region of interest approach. WMH was rated on a semiquantitative scale as the percent of total volume of white matter. ResultsHippocampal volume was significantly reduced in CIND and demented individuals, and WMH were significantly increased in demented subjects. MI subjects did not have any significant changes in hippocampal volume or WMH. The risk for developing dementia was significantly and comparably increased in subjects with either hippocampal atrophy or high WMH. However, the risk for dementia increased dramatically in subjects with both hippocampal atrophy and a high degree of WMH. ConclusionReductions in hippocampal volume may be present before dementia but not until cognitive impairment is relatively severe. Because there is a synergistic effect between high WMH and hippocampal atrophy, interactions between vascular and degenerative processes may be important determinants of dementia.

How valid is the ICD-9-CM based AHRQ patient safety indicator for postoperative venous thromboembolism?

Background:Hospital administrative data are being used to identify patients with postoperative venous thromboembolism (VTE), either pulmonary embolism (PE) or deep-vein thrombosis (DVT). However, few studies have evaluated the accuracy of these ICD-9-CM codes across multiple hospitals. Methods and Materials:The Agency for Healthcare Research and Quality (AHRQ) Patient Safety Indicator (PSI)-12 was used to identify cases with postoperative VTE in 80 hospitals that volunteered for either an AHRQ or University HealthSystem Consortium (UHC) validation project. Trained abstractors using a standardized tool and guidelines retrospectively verified all coded VTE events. Results:In the combined samples, the positive predictive value of the set of prespecified VTE codes for any acute VTE at any time during the hospitalization was 451 of 573 = 79% (95% CI: 75%–82%). However, the positive predictive value for acute lower extremity DVT or PE diagnosed after an operation was 209 of 452 = 44% (95% CI: 37%–51%) in the UHC sample and 58 of 121 = 48% (95% CI: 42–67%) in the AHRQ sample. Fourteen percent of all cases had an acute upper extremity DVT, 6% had superficial vein thrombosis and 21% had no acute VTE, however, 61% of the latter had a documented prior/chronic VTE. In the UHC cohort, the sensitivity for any acute VTE was 95.5% (95% CI: 86.4%–100%); the specificity was 99.5% (95% CI: 99.4%–99.7%). Conclusion:Current PSI 12 criteria do not accurately identify patients with acute postoperative lower extremity DVT or PE. Modification of the ICD-9-CM codes and implementation of “present on admission” flags should improve the predictive value for clinically important VTE events.

Positive predictive value of the AHRQ accidental puncture or laceration patient safety indicator.

Objective:Patient Safety Indicator (PSI) 15, or “Accidental Puncture or Laceration” (APL), of the US Agency for Healthcare Research and Quality was recently endorsed as a consensus standard for quality of care by the National Quality Forum. We sought to determine the positive predictive value (PPV) of this indicator. Methods:We conducted a retrospective cross-sectional study of hospitalization records that met PSI 15 criteria. We sampled cases from 32 geographically diverse hospitals, including both teaching and nonteaching hospitals, between October 1, 2005 and March 31, 2007. Trained abstractors from each center reviewed randomly sampled medical records, using a standard instrument. We determined the PPV of the indicator and conducted descriptive analyses of the cases. Results:Of the 249 cases that met PSI 15 criteria, 226 (91%; 95% CI: 88%–94%) represented true APL. Fifty-six of the true APL cases (24%) represented injuries that generally would be expected to heal without repair, yielding, from the standpoint of clinical relevance, a PPV of 68% (95% CI: 62%–74%). True positive cases that would typically warrant repair (n=170) were most likely to involve the gastrointestinal tract (30%), bladder (25%), dura (19%), or an important blood vessel (16%). In 97 of the true APL cases (43%), adhesions or other scar tissue were thought to have contributed to the complication. The 23 false-positive cases involved no apparent event other than normal operative conduct (n=7), a complication other than APL (bleeding, infection, dislodgement of a gastrostomy tube, or fracture) (7), an APL present on admission (5), or a disease-related lesion (4). Conclusions:Although PSI 15 is highly predictive of APL from a coding perspective, the indicator is less predictive of APL that could be considered clinically important. A significant proportion of cases represent relatively inconsequential injuries or injuries for which the risk may have been acceptable relative to the goals of the procedure.

Detection of postoperative respiratory failure: How predictive is the agency for healthcare research and quality's patient safety indicator?

BACKGROUND Patient Safety Indicator (PSI) 11, or postoperative respiratory failure, was developed by the US Agency for Healthcare Research and Quality to detect incident cases of respiratory failure after elective operations through use of ICD-9-CM diagnosis and procedure codes. We sought to determine the positive predictive value (PPV) of this indicator. STUDY DESIGN We conducted a retrospective cross-sectional study, sampling consecutive cases that met PSI 11 criteria from 18 geographically diverse academic medical centers on or before June 30, 2007. Trained abstractors from each center reviewed medical records using a standard instrument. We assessed the PPV of the indicator (with 95% CI adjusted for clustering within centers) and conducted descriptive analyses of the cases. RESULTS Of 609 cases that met PSI 11 criteria, 551 (90.5%; 95% CI, 86.5-94.4%) satisfied the technical criteria of the indicator and 507 (83.2%; 95% CI, 77.2-89.3%) represented true cases of postoperative respiratory failure from a clinical standpoint. The most frequent reasons for being falsely positive were nonelective hospitalization, prolonged intubation for airway protection, and insufficient evidence to support a diagnosis of acute respiratory failure. Fifty percent of true-positive cases involved substantial baseline comorbidities, and 23% resulted in death. CONCLUSIONS Although PSI 11 predicts true postoperative respiratory failure with relatively high frequency, the indicator does not limit detection to preventable cases. The PPV of PSI 11 might be increased by excluding cases with a principal diagnosis suggestive of a nonelective hospitalization and those with head or neck procedures. Removing the diagnosis code criterion from the indicator might also increase PPV, but would decrease the number of true positive cases detected by 20%.

Positive predictive value of the Agency for Healthcare Research and Quality Patient Safety Indicator for central line-related bloodstream infection ("selected infections due to medical care").

&NA; As part of the Agency for Healthcare Research and Quality Patient Safety Indicator (PSI) Validation Pilot Project, we evaluated the criterion validity of PSI 7. At the time of this study, PSI 7 was entitled “Selected Infections Due to Medical Care” and targeted catheter–related infections and inflammatory reactions. We conducted a retrospective cross–sectional study of 23 volunteer U.S. hospitals, where trained abstractors reviewed a sample of records that met PSI 7 criteria from October 1, 2005 to March 31, 2007. Of the 191 cases that met PSI 7 criteria, 104 (positive predictive value = 54%, 95% confidence interval: 40–69%) represented true infections. Of these cases, 77 (74%) were associated with central venous catheters, 15 (15%) were associated with peripheral intravenous (n=13) and or or arterial catheters (n=6), and 12 (11%) were associated with unknown catheters. Of the 87 (46%) false–positive cases, 41 (47%) did not have a qualifying infection identified by the abstractor, 38 (44%) had an infection present on admission, and 8 (9%) had an exclusionary diagnosis. PSI 7 has a low positive predictive value compared with other PSIs recently studied. Present on admission diagnoses and improved coding for infections related to central venous catheters (implemented October 2007) may improve validity.

Correlates of memory function in community-dwelling elderly: The importance of white matter hyperintensities

We sought to identify magnetic resonance- (MR)-imaged structures associated with declarative memory in a community-dwelling sample of elderly Mexican-American individuals with a spectrum of cognitive decline. Measured structures were the hemispheric volumes of the hippocampus (HC), parahippocampal gyrus, and remaining temporal lobes, as well as severity of white matter signal hyperintensities (WMH). Participants were an imaged subsample from the Sacramento Area Latino Study of Aging (SALSA), N = 122. Individuals were categorized as normal, memory impaired (MI), cognitively impaired non-demented (CIND), or demented. We show that WMH was the strongest structural predictor for performance on a delayed free-recall task (episodic memory) in the entire sample. The association of WMH with delayed recall was most prominent in elderly normals and mildly cognitively impaired individuals with no dementia or impairment of daily function. However, the left HC was associated with verbal delayed recall only in people with dementia. The right HC volume predicted nonverbal semantic-memory performance. We conclude that WMH are an important pathological substrate that affects certain memory functions in normal individuals and those with mild memory loss and discuss how tasks associated with WMH may rely upon frontal lobe function.

Improved coding of postoperative deep vein thrombosis and pulmonary embolism in administrative data (AHRQ patient safety indicator 12) after introduction of new ICD-9-CM diagnosis codes

Background:Symptomatic venous thromboembolism is a common postoperative complication. The Agency for Healthcare Research and Quality (AHRQ) has developed a Patient Safety Indicator 12 to assist hospitals, payers, and other stakeholders to identify patients who experienced this complication. Objectives:To determine whether newly created and recently redefined ICD-9-CM codes improved the criterion validity of Patient Safety Indicator 12, based on new samples of records dated after October 2009. Research Design, Subjects, Measures:Two sources of data were used: (1) UHC retrospective case-control study of risk factors for acute symptomatic venous thromboembolism occurring within 90 days after total knee arthroplasty in teaching hospitals; (2) chart abstraction data by volunteer hospitals participating in the Validation Pilot Project of the AHRQ. Results:In the UHC sample, the positive predictive value (PPV) was 99% (125/126) and the negative predictive value was 99.4% (460/463). In the AHRQ sample, the overall PPV was 81% (126/156). Conclusions:The PPV based on both samples shows substantial improvement compared with the previously reported PPVs of 43%–48%, suggesting that changes in ICD-9-CM code architecture and better coding guidance can improve the usefulness of coded data.

Using the Agency for Healthcare Research and Quality patient safety indicators for targeting nursing quality improvement.

Quantifying the critical impact nurses have on the prevention and early recognition of potential complications and adverse events, such as those identified by the Agency for Healthcare Research and Quality (AHRQ) patient safety indicators (PSI), is becoming increasingly important. In this paper, we describe how the AHRQ PSI may be used to identify nursing-specific opportunities to improve care based on data from the national AHRQ PSI validation pilot project.

Designing an Abstraction Instrument: Lessons from Efforts to Validate the AHRQ Patient Safety Indicators

BACKGROUND The U.S. Agency for Healthcare Research and Quality (AHRQ) and other organizations have developed quality indicators based on hospital administrative data. Characteristics of effective abstraction instruments were identified for determining both the positive predictive value (PPV) of Patient Safety Indicators (PSIs) and the extent to which hospitals and clinicians could have prevented adverse events. METHODS Through an iterative process involving nurse abstractors, physicians, and nurses with quality improvement experience, and health services researchers, 25 abstraction instruments were designed for 12 AHRQ provider-level morbidity PSIs. Data were analyzed from 13 of these instruments, and data are being collected using several more. FINDINGS Common problems in designing the instruments included avoiding uninformative questions and premature termination of the abstraction process, anticipating misinterpretation of questions, allowing an appropriate range of response options; using clear terminology, optimizing the flow of the abstraction process, balancing the utility of data against abstractor burden, and recognizing the needs of end users, such as hospitals and quality improvement professionals and researchers, for the abstracted information. CONCLUSIONS Designing medical record abstraction instruments for quality improvement research involves several potential pitfalls. Understanding how we addressed these challenges might help both investigators and users of outcome indicators to appreciate the strengths and limitations of outcome-based quality indicators and tools designed to validate or investigate such indicators within provider organizations.