Clinical performance measures: the changing status of peritoneal dialysis

BACKGROUND

The Peritoneal Dialysis-Clinical Performance Measures Project (PD-CPM) characterizes peritoneal dialysis within the U.S. Current survey results are reported and compared to those of previous years.

METHODS

Prevalence data from random national samples of adult peritoneal dialysis (PD) patients participating in the United States End-Stage Renal Disease (ESRD) program have been collected annually since 1995.

RESULTS

In 1995, 79% of the respondents used continuous ambulatory peritoneal dialysis (CAPD) rather than automated peritoneal dialysis (APD). The mean hematocrit (Hct) of PD patients was 32% and only 66% of individuals had a measurement of dialysis adequacy reported. The mean weekly Kt/Vurea (wKt/V) and weekly creatinine clearance (wCCr) reported for CAPD patients in 1995 were 1.9 and 67 L/1.73 m2/week, respectively. In 2000 the median age of PD patients was 55 years and 63% were white. The leading cause of ESRD was diabetes mellitus (34%) and 54% of adult PD patients performed some form of APD rather than CAPD. Age, sex, size, hematocrit, peritoneal permeability, dialysis adequacy, residual renal function and nutritional indices did not differ between APD and CAPD patients. The mean hemoglobin (Hb) for the 2000 PD-CPM population was 11.6 +/- 1.4 g/dL (mean +/- 1 SD) and 11% of patients had an average Hb below 10 g/dL. The average serum albumin was 3.5 +/- 0.5 g/dL by the bromcresol green method and 56% of subjects had an average serum albumin equal to or above 3.5 g/dL (or 3.2 g/dL by bromcresol purple). In 2000 85% of patients had a dialysis adequacy measurement reported and the mean calculated wKt/V and wCCr were 2.3 +/- 0.6 and 72.7 +/- 24.9 liters/1.73 m2/week for CAPD patients and 2.3 +/- 0.6 and 71.6 +/- 25.1 L/1.73 m2/week for APD patients. PD subjects had a mean body weight of 76 +/- 19 kg and body mass index (BMI) of 27.5 +/- 6.4 kg/m2. The protein equivalent of nitrogen appearance (nPNA) of these patients was 0.95 +/- 0.31 g/kg/day, their normalized creatinine appearance rate (nCAR) equaled 17 +/- 6.5 mg/kg/day, resulting in a percent lean body mass (%LBM) of 64 +/- 17% of actual body weight. Serum albumin correlated in a positive fashion with BMI, nPNA, nCAR and %LBM, but not with wCCr.

CONCLUSIONS

The majority of indicator variables monitored by the PD-CPM have improved since 1995. PD patients have higher hemoglobins and a greater proportion of patients meet the criteria for adequate dialysis. Serum albumin values, however, remain marginal and unchanged over the five-year project. Furthermore, serum albumin values fail to correlate with the intensity of renal replacement therapy and are not strongly correlated with alternative estimates of nutritional status.

Nutritional markers during peritoneal dialysis: data from the 1998 Peritoneal Dialysis Core Indicators Study

OBJECTIVE

This analysis explores the nutritional status of adult U.S. peritoneal dialysis (PD) patients.

DESIGN

The Peritoneal Dialysis Core Indicators Study is a prospective cross-sectional prevalence survey describing the care provided to a random sample of adult U.S. PD patients.

METHODS AND POPULATION

Prevalence data were collected from a national random sample of 1381 adult PD patients participating in the United States End Stage Renal Disease (ESRD) program.

RESULTS

The median age of these patients was 55 years, 61% were Caucasian; the leading cause of ESRD was diabetes mellitus. Age, sex, size, peritoneal permeability, dialysis adequacy, and nutritional indices did not differ between patients on continuous ambulatory PD and patients on automated PD. The dialysis prescriptions employed achieved mean weekly Kt/V urea (wKt/V) and creatinine clearance (wCCr) values of 2.22 +/- 0.57 and 67.8 +/- 22.5 L/1.73 m2/week, respectively. The PD patients were large, with a mean body weight of 77 +/- 21 kg and body mass index (BMI) of 27 +/- 8.6 kg/m2. The mean serum albumin of these patients was 3.5 +/- 0.51 g/dL, and 43% of values fell below the National Kidney Foundation Dialysis Outcomes Quality Initiative's desired range. The PD patients had a normalized protein equivalent of nitrogen appearance (nPNA) of 1.0 +/- 0.57 g/kg/day, a normalized creatinine appearance rate (nCAR) of 17 +/- 7.3 mg/kg/day, and an estimated lean body mass (%LBM) of 62% +/- 18% of body weight. Serum albumin correlated positively with patient size, nCAR, and nPNA, but negatively with age, the presence of diabetes mellitus, female gender, erythropoietin dose, the creatinine dialysate-to-plasma ratio results of peritoneal equilibration testing, and the dialysis portion of the wCCr. The duration of ESRD experience correlated negatively with both serum albumin and patient size, although these relationships were complex.

CONCLUSION

Peritoneal dialysis patients generally have marginal serum albumin levels, a finding incongruent with alternative measures of nutritional status, such as weight, BMI, and creatinine generation. Serum albumin is reduced in patients with high peritoneal permeability (i.e., rapid transporters) and, because these patients generally have higher than average wCCr values, serum albumin is inversely correlated with the dialysis component of the wCCr. The presumptive nutritional indicators (BMI, %LBM, nPNA, and serum albumin) provide disparate estimates, varying from 10% to 50% for the prevalence of nutritionally stressed PD patients.

Quantifying the characteristics of unambiguous chest radiography reports in the context of pneumonia

RATIONALE AND OBJECTIVES

The purpose of this study was to statistically identify some characteristics of unambiguous (ie, clear) chest radiography reports in the context of acute bacterial pneumonia.

MATERIALS AND METHODS

Seven physicians individually read 292 chest radiography reports to determine if they contained radiologic evidence of pneumonia. Unambiguous reports were defined as those that physicians unanimously classified as supporting or not supporting the diagnosis of pneumonia. Ambiguous reports were assigned degrees of ambiguity on the basis of how much disagreement they caused among the physicians. Characteristics of unambiguous reports as described in the literature were manually quantified and assigned to every report. To identify characteristics that statistically distinguished unambiguous from ambiguous reports, the authors performed an ordinal logistic regression analysis for which the dependent variable was the number of dissenting votes the report received and the independent variables were the quantified characteristics of the report.

RESULTS

Six independent variables were statistically significantly associated with unambiguous reports (P < .05). Three were positively associated: an interpretation of whether findings supported the diagnosis of pneumonia in reports with pneumonia-related observations, short sentences, and redundancy of pneumonia-related observations. Three were negatively associated: high use of uncertainty modifiers for pneumonia-related observations, use of only descriptive terms to describe pneumonia-related observations, and insufficient amount of pneumonia-related information.

CONCLUSION

The most influential characteristic of an unambiguous chest radiography report was an interpretation of whether the radiograph supported the diagnosis of pneumonia when findings could be indicative.

Intermediate outcomes by race and ethnicity in peritoneal dialysis patients: results from the 1997 ESRD Core Indicators Project. National ESRD Core Indicators Workgroup

BACKGROUND

Hispanics are the fastest growing minority group in the United States, and approximately 10% of all end-stage renal disease (ESRD) patients are Hispanic. Few data are available, however, regarding dialysis adequacy and anemia management in Hispanic patients receiving peritoneal dialysis in the U.S.

METHODS

Data from the Health Care Financing Administration (HCFA) ESRD Core Indicators Project were used to assess racial and ethnic differences in selected intermediate outcomes for peritoneal dialysis patients.

RESULTS

Of the 1219 patients for whom data were available from the 1997 sample, 9% were Hispanic, 24% were non-Hispanic blacks, and 59% were non-Hispanic whites. Hispanics were more likely to have diabetes mellitus as a cause of ESRD compared to blacks or whites, and both Hispanics and blacks were younger than white patients (both p < 0.001). Although whites had higher weekly Kt/V and creatinine clearance values compared to blacks or Hispanics (p < 0.05), blacks had been dialyzing longer (p < 0.01) and were more likely to be anuric compared to the other two groups (p < 0.001). Blacks had significantly lower mean hematocrit values (p < 0.001) and a greater proportion of patients who had a hematocrit level less than 28% (p < 0.05) compared to Hispanics or whites, despite receiving significantly larger weekly mean epoetin alfa doses (p < 0.05) and having significantly higher mean serum ferritin concentrations (p < 0.01). Multivariate logistic regression analysis revealed significant differences by race/ethnicity for experiencing a weekly Kt/V urea < 2.0 and hypertension, but not for other intermediate outcomes examined (weekly creatinine clearance < 60 L/week/1.73 m2, Hct < 30%, and serum albumin < 3.5/3.2 g/dL).

CONCLUSION

Hispanics had adequacy values similar to blacks and anemia parameters similar to whites. Additional studies are needed to determine the etiologies of the differences in intermediate outcomes by racial and ethnic groupings in peritoneal dialysis patients.

Can dialysis therapy be improved? A report from the ESRD Core Indicators Project

We assessed the association between quality improvement interventions conducted during the End-Stage Renal Disease (ESRD) Core Indicators Project and changes in the adequacy of hemodialysis between 1993 and 1996. Improvement of hemodialysis adequacy was measured by baseline and annual urea reduction ratios (URRs) in representative samples of ESRD Network patients. Random samples of in-center hemodialysis patients aged 18 years and older who had received hemodialysis during the fourth quarters of 1993, 1994, 1995, and 1996 were used to calculate Network-specific outcomes. A mean URR was calculated for each patient using the first pretreatment and posttreatment blood urea nitrogen for October, November, and December of each study year. Both national and Network-specific interventions were used to provide feedback reports and technical assistance to treatment centers to foster improvement in hemodialysis adequacy. All Networks distributed reports on the patterns of treatment center URR levels and physician and patient educational materials to each center in the Network. Each Network selected an annual 10% sample of treatment centers in 1994 and 1995 and conducted quality improvement activities to assist the selected centers to improve dialysis adequacy. We defined Network-specific interventions by a survey of the 18 Networks conducted during 1995 to determine the characteristics of Network-specific activities used to improve adequacy of hemodialysis. The outcome of interest was the change over time in Network-specific URR value. Sustained improvement in the URR occurred within all 18 Networks between 1993 and 1996. The mean national URR increased from 62.7% in 1993 to 66. 8% in 1996. The proportion of patients with URR >/= 65% increased from 43% in 1993 to 68% in 1996. Networks reported implementing a variety of intervention strategies that included educational activities, continuous quality improvement workshops, on-site assistance, and supervision of selected treatment facilities until care improved. Network-specific interventions independently associated with an increased rate of improvement in URR included prolonged supervision of the selected facilities. We concluded that the sustained improvement in hemodialysis care that occurred after the inception of the ESRD Core Indicators Project was associated with specific ESRD Network interventions.

Racial/ethnic analysis of selected intermediate outcomes for hemodialysis patients: results from the 1997 ESRD Core Indicators Project

Principal goals of the End-Stage Renal Disease (ESRD) Core Indicators Project are to improve the care provided to ESRD patients and to identify categorical variability in intermediate outcomes of dialysis care. The purpose of the current analysis is to extend our observations about the variability of intermediate outcomes of ESRD care among different racial and gender groups to a previously unreported group, Hispanic Americans. This group is a significant and growing minority segment of the ESRD population. A random sample of Medicare-eligible adult, in-center, hemodialysis patients was selected and stratified from an end-of-year ESRD patient census for 1996. Of the 6,858 patients in the final sample, 45% were non-Hispanic whites, 36% were non-Hispanic blacks, and 11% were Hispanic. Whites were older than blacks or Hispanics (P < 0.001). Hispanics were more likely to have diabetes mellitus as a primary diagnosis than either blacks or whites (P < 0.001). Even though they received longer hemodialysis times and were treated with high-flux hemodialyzers, blacks had significantly lower hemodialysis doses than white or Hispanic patients (P < 0.001). The intradialytic weight losses were greater for blacks (P < 0.05). The delivered hemodialysis dose was lower for blacks than for whites or Hispanics whether measured as a urea reduction ratio (URR) or as the Kt/V calculated by the second generation formula of Daugirdas (median 1. 32, 1.36, and 1.37, respectively, P < 0.001). Hispanics and whites had modestly higher hematocrits than blacks (33.2, 33.2, and 33.0%, respectively, P < 0.01). There was no significant difference among groups in the weekly prescribed epoetin alfa dose ( approximately 172 units/kg/week). A significantly greater proportion of Hispanic patients had transferrin saturations >/=20% compared with the other two groups (P < 0.001). Logistic regression modeling revealed that whites were significantly more likely to have serum albumin <3. 5(BCG)/3.2(BCP) gm/dL (OR 1.4, p < 0.01); blacks were significantly more likely to have a delivered Kt/V < 1.2 (OR 1.4, P < 0.001) and hematocrit <30%, (OR 1.2; P < 0.05) and both blacks and Hispanics were significantly more likely to have a delivered URR < 65% (OR 1.5, P < 0.001 and 1.2, P < 0.05, respectively).

Trends in clinical indicators of care for adult peritoneal dialysis patients in the United States from 1995 to 1997. ESRD Core Indicators Workgroup

BACKGROUND

This article describes the changes in four core indicator variables: dialysis adequacy, hematocrit, serum albumin, and blood pressure in peritoneal dialysis CAPD and cycler patients over a three-year period.

METHODS

A national random sample of adult peritoneal dialysis patients in the United States was drawn each study period. Clinical data abstraction forms were completed by facility staff for patients selected for the sample, returned to the respective network, then forwarded to the Health Care Financing Administration for analysis.

RESULTS

The mean weekly Kt/V urea for CAPD patients increased from 1.91 in 1995 to 2.12 in 1997 (P < 0.001) and for cycler patients, from 2.12 in 1996 to 2.24 in 1997 (P < 0.05). The mean weekly creatinine clearance for CAPD patients increased from 61.48 liter/week/1.73 m2 in 1995 to 65.84 liter/week/1.73 m2 in 1997 (P < 0.05). For cycler patients, it increased from 63.37 liter/week/1.73 m2 in 1996 to 67.45 liter/week/1.73 m2 in 1997 (P < 0.05). Despite this increase in adequacy values, less than 40% of peritoneal dialysis patients in 1997 had weekly Kt/V urea or creatinine clearance values that met subsequently published National Kidney Foundation's Dialysis Outcomes Quality Initiative (DOQI) guidelines. These data suggest that the dialysis prescription may not be adequately modified to compensate for increased body weight and for decreased residual renal function as years on dialysis increase. The average hematocrit value increased modestly in both CAPD and cycler patients from 1995 to 1997, and the number of patients with a hematocrit of less than 25% decreased from 6% in 1995 to 1.4% in 1997 (P < 0.001). Both serum albumin values and systolic and diastolic blood pressure values were essentially unchanged during the three-year period of observation.

CONCLUSIONS

Despite improvements in dialysis adequacy and hematocrit values, there remains much room for improvement in these core indicator values.

Changes in dialysis units' quality improvement practices from 1994 to 1996

In 1994, the Health Care Financing Administration initiated a nationwide effort to improve care to Medicare's end stage renal disease (ESRD) beneficiaries by reshaping the manner in which the ESRD Network Organizations measure and assess the quality of dialysis services. The new approach was named the ESRD Health Care Quality Improvement Program (HCQIP). It embodies themes such as the development of quality indicators and support for continuous improvement. Projects such as the ESRD Core Indicators Project and the National Anemia Cooperative Project are geared toward assisting dialysis providers to improve patient care. In an effort to document changes in dialysis quality practices associated with the ESRD HCQIP, surveys were sent by Network staff to the head nurses of all dialysis units in 1994, and a random sample of units in 1996. Analysis of the survey responses was performed identifying self-reported changes in dialysis units' quality improvement activities. Results indicate that practice changes are taking place, that they are generalizable to all dialysis units in the country, and that they are associated with improvement in patient outcomes. Trends in quality improvement activities are identified and conclusions are drawn about what impact these activities have on patient care.

1996 Peritoneal Dialysis Core Indicators Study: report on nutritional indicators

OBJECTIVE

The 1996 Peritoneal Dialysis Core Indicators Study illustrates the conduct of peritoneal dialysis in the United States during 1996. DESIGN AND PATIENT POPULATION: The survey is a medical records audit of 1317 randomly selected adult U.S.A. Medicare patients using peritoneal dialysis during 1996.

OUTCOME MEASURES

Abstracted data included basic demographic characteristics, dialysis prescription, delivered dialysis dose, residual renal function, serum albumin, hematocrit, anemia management, and patient status.

RESULTS

The survey included 785 patients using continuous ambulatory peritoneal dialysis (CAPD) and 423 using automated peritoneal dialysis (APD) primarily in the form of continuous cycling peritoneal dialysis (CCPD). Except for the prescription mechanics and a greater likelihood that African-Americans would use CAPD, the groups did not differ substantially from one another. Evaluation of patient weight (W), body mass index (BMI), residual renal function, average serum albumin, protein equivalent of nitrogen appearance (nPNA), and dialysis efficiency as weekly fractional urea nitrogen removal (wKt/Vurea) and weekly creatinine clearance (wCrCl) revealed a picture of reasonable dialysis delivery and marginal protein nutrition. Additionally, there was little evidence that "dialysis efficiency," over the range assessed, had a major influence on nutritional status. Despite a tendency toward obesity (body weight = 76.6+/-20.0 kg and BMI = 27+/-7), 47% of patients had an average serum albumin below"normal" (3.5 g/dL by bromcresol green) and 70% had a nPNA below 1.0 g/kg/day.

CONCLUSIONS

Peritoneal dialysis patients appear to have marginal protein reserves despite surfeit energy stores.

1996 peritoneal dialysis--core indicators report

The 1996 Peritoneal Dialysis-Core Indicators Study (PD-CIS) retrospectively reviews a random sample of peritoneal dialysis patients from the United States End-Stage Renal Disease (ESRD) program. Peritoneal dialysis (PD) patients are more likely to have a primary diagnosis of glomerulonephritis, less likely to be of African-American heritage, and are younger than hemodialysis patients. One third of PD patients now perform some form of automated peritoneal dialysis (APD) rather than continuous ambulatory peritoneal dialysis (CAPD). The dialysis prescriptions currently employed do not appear to be based on kinetic principles, and the intensity of dialysis achieved is below the proposed minimal guidelines for 30% of patients. In 1996, the mean dialysis index or wKt/Vurea for CAPD patients was 2.0 +/- 0.5 and was not significantly altered from the 1995 value of 2.1. Eighty-four percent of CAPD patients perform four or fewer exchanges daily, and only 27% of patients have prescriptions using infusion volumes greater than 2 L. Although hematocrits have improved since 1995, 30% of PD patients have a hematocrit below 30%. The mean serum albumin for PD patients is 3.5 g/dL, and 25% of patients have a 6-month average serum albumin value below 3.2 g/dL. In general, the indices monitored as predictive of health and well-being of PD patients afford significant opportunity for improvement.

Automatic extraction of PIOPED interpretations from ventilation/perfusion lung scan reports

Free-text documents are the main type of data produced by a radiology department in a hospital information system. While this type of data is readily accessible for clinical data review it can not be accessed by other applications to perform medical decision support, quality assurance, and outcome studies. In an attempt to solve this problem, natural language processing systems have been developed and tested against chest x-rays reports to extract relevant clinical information and make it accessible to other computer applications. We have used a natural language processing tool called SymText to extract relevant clinical information from a different type of radiology report, the Ventilation/Perfusion lung scan report. Results of this effort can be analyzed in terms of precision and recall. The overall precision was 0.88 and recall was 0.92. In addition, the natural language processing system functions differently in reports with and without an impression section. If this type of information can be successfully extracted from radiology reports, one can develop quality monitors for the diagnostic performance of the radiologist by correlating the impressions with gold standard data present in a hospital information system. Avoiding the manual effort previously necessary to create quality assurance data, can lead to a higher frequency of quality review in a radiology department.

Developing a radiology data base for quality assurance

Radiology Information Systems (RIS) are designed to capture and manage the data associated with ordering, executing, reporting, and billing x-ray procedures. The HELP Hospital Information System contains a radiology subsystem that supports these functions. In an effort to enhance quality assurance initiatives, we have created a supplemental data base. This data base contains not only the data traditionally generated by RISs but also data from the hospital system that is relevant to quality assurance. One of the goals associated with this data base is to use techniques from the discipline of Continuous Quality Improvement (CQI) in the radiology department. A focus of our initial efforts has been the time necessary to provide x-ray reports to ordering physicians once the imaging examination has been performed. Efforts to manage the portion of this time interval caused by transcription have resulted in a substantial decrease in the time required for this function. A second goal of this project is to evaluate the quality of x-ray ordering. This objective requires a computerized record of the outcome of the x-ray procedure. Initial analysis of data derived from this data base indicates significant differences in the ordering behavior for computed tomography (CT) examinations among a test group of physicians. A third goal is to do quality assurance on x-ray reports. Experience with pilot systems has shown promising results using a mathematical model of report quality. We hope to leverage these techniques and this quality assurance data base to define a COI process for medical reports in general and for x-ray reports in particular.

Improvement in adequacy of delivered dialysis for adult in-center hemodialysis patients in the United States, 1993 to 1995

The objective of this review is to describe the adequacy of delivered dialysis provided to in-center hemodialysis patients in the United States and to compare the findings with published guidelines. The medical records of random samples of 6,138, 6,919, and 6,861 patients in hemodialysis facilities were studied from all Medicare-eligible adult in-center hemodialysis patients alive on December 31, 1993, 1994, and 1995, respectively. The main clinical measure used was the urea reduction ratio (URR), the mean of which was 0.63 in 1993, 0.64 in 1994, and 0.66 in 1995. The proportion of patients with URR > or = 0.65, as recommended by the Renal Physicians Association and a National Institutes of Health Consensus Development Conference Statement, increased from 43% in 1993 to 49% in 1994 and 59% in 1995. In each of these 3 years, women were more likely than men to have a URR > or = 0.65 (1993: 54% v 31%, odds ratio 2.6; 1994: 61% v 38%, odds ratio 2.5; and 1995: 70% v 50%, odds ratio 24), as were older patients (65+ years) compared with younger patients (18 to 44 years) (1993: 47% v 37%, odds ratio 1.4; 1994: 54% v 45%, odds ratio 1.5; and 1995: 65% v 53%, odds ratio 1.6) and white patients compared with black patients (1993: 46% v 36%, odds ratio 1.5; 1994: 53% v 43%, odds ratio 1.5; and 1995: 63% v 54%, odds ratio 1.4). There was also substantial geographic variation in the proportion of patients receiving hemodialysis with a URR > or = 0.65. In conclusion, marked differences existed in 1993, 1994, and 1995 between observed practice and consensus guidelines for the delivery of adequate dialysis. Nevertheless, notable improvement occurred during this time period. A system to monitor further improvements in hemodialysis care in the United States is in place.

Implementing the Health Care Quality Improvement Program in the Medicare ESRD Program: a new era of quality improvement in ESRD

Improving the quality of health care is a central challenge for America's health care system. The mission of the End-Stage Renal Disease (ESRD) program is to promote the quality, effectiveness, and efficiency of ESRD patient care and program administration. The program provides an ideal opportunity to demonstrate the use of information to help clinicians analyze and improve the care they deliver to patients in an ambulatory setting. This is possible because the program has established regional surveillance systems, called ESRD Networks, that gather information on the occurrence and outcomes of treatment of Medicare beneficiaries with ESRD. The Health Care Financing Administration, which is responsible for the administration of the program, and the renal community have worked together since 1990 to identify ways of incorporating new methods of quality improvement into the program. These methods include statistical evaluation of the processes and outcomes of care in dialysis populations; communicating recommended practices with clinical guidelines and algorithms; regional peer review and feedback (ie, technical assistance and/or collaborations for quality improvement); interventions that focus on the provision of assistance for quality improvement efforts; continuing collection and active feedback of data to providers; and a commitment to continue to evaluate and revise quality improvement activities to reflect lessons learned and newly identified needs. These ideas have been included in the 1994-1997 scope of work for the ESRD Networks and is called the ESRD Health Care Quality Improvement Program (HCQIP). This article describes the background for the ESRD HCQIP and the program's elements.

A data-driven approach to improving the care of in-center hemodialysis patients

Health care providers, patients, the end stage renal disease (ESRD) networks, and HCFA have developed the ESRD Health Care Quality Improvement Program (HCQIP) in an effort to assess and improve care provided to ESRD patients. Currently, the ESRD HCQIP focuses on collecting information on quality indicators (QIs) for treatment of anemia, delivery of adequate dialysis, nutritional status, and blood pressure control for adult in-center hemodialysis patients. QIs were measured in a national probability sample of ESRD patients, and interventions and evaluations of the interventions are beginning. The ESRD HCQIP illustrates a way to mobilize the strengths of the public and private sectors to achieve improved care for special populations.

Integrating Radiology and Hospital Information Systems: the advantage of shared data

Information management is central to modern patient care. Computerization of information management has resulted in both departmental systems which serve information needs in locations such as the Radiology Department and in hospital-wide information systems which seek to integrate management of clinical data from many departments. For each of these systems to achieve the goal of maximizing both the effectiveness of health care workers and the quality of patient care, they need to share the data that they capture. Below we discuss a variety of applications, both currently available and in the realm of research protocols, that depend on a high level of communication between Radiology Information Systems and Hospital Information Systems. These examples suggest the benefits of integrating the medically relevant data collected by all of the computer-based information systems in the hospital setting.

Quality control in a medical information system

Quality assurance techniques provide an opportunity to identify sources of error and to provide the feedback necessary to prevent their repetition. The authors outline an effort to define the steps required for effective quality management procedures in a computerized medical information system (MIS). The computerized management of medical information can be used not only to enhance current quality management activities but also to extend the realm of quality assurance to areas that have heretofore resisted management. Quality-management techniques have the potential for measuring and improving medical decision making processes central to patient care.

Chest radiography: a tool for the audit of report quality

In a radiology department, clinical audit implies multiple readings of selected images to identify those findings that should be recognized and to document any departure from this standard for each radiologist. The authors developed an alternate approach for an audit on the basis of clinical outcomes collected in a medical computing facility. Techniques borrowed from information theory were used to measure the clinical information contributed by radiologists as they interpreted chest radiographs. The reported findings were evaluated in light of the discharge diagnosis. The scores generated quantified the information contributed to the final diagnosis by the radiologist's description. This audit approach was tested in a group of 100 chest radiographs. Significant differences were found in the mean scores for information contributed by five different readers. These differences were similar to differences demonstrated in audits by means of multiple readings of chest radiographs. These results support use of a form of audit that is substantially less expensive and time consuming than that typically used in radiology departments.

Computerized extraction of coded findings from free-text radiologic reports. Work in progress

A computerized data acquisition tool, the special purpose radiology understanding system (SPRUS), has been implemented as a module in the Health Evaluation through Logical Processing Hospital Information System. This tool uses semantic information from a diagnostic expert system to parse free-text radiology reports and to extract and encode both the findings and the radiologists' interpretations. These coded findings and interpretations are then stored in a clinical data base. The system recognizes both radiologic findings and diagnostic interpretations. Initial tests showed a true-positive rate of 87% for radiographic findings and a bad data rate of 5%. Diagnostic interpretations are recognized at a rate of 95% with a bad data rate of 6%. Testing suggests that these rates can be improved through enhancements to the system's thesaurus and the computerized medical knowledge that drives it. This system holds promise as a tool to obtain coded radiologic data for research, medical audit, and patient care.

Efficient biphasic spin-echo magnetic resonance imaging

The concept of temporal echo multiplexing is defined and used to develop rapid biphasic spin-echo sequences for imaging the heart. Three imaging sequences, based on four-echo and two-echo multiplexing and rapid single echo (i.e., conventional spin-echo imaging), are compared. Preliminary results indicate that two-echo multiplexing yields a significantly reduced acquisition time window with image quality that is only slightly inferior to single-echo imaging. Single-echo biphasic imaging results in the most consistent image quality.

Revision of diagnostic logic using a clinical database

Statistical pattern-recognition techniques have been frequently applied to the problem of medical diagnosis. Sequential Bayesian approaches are appealing because of the possibility of generating the underlying sensitivities, specificities, and prevalence statistics from the estimates of medical experts. The accuracy of these estimates and the consequences of inaccuracies carry implications for the future development of this type of system. In an effort to explore these subjects, the authors used statistics derived from a clinical database to revise the diagnostic logic in a Bayesian system for generating a differential diagnostic list. Substantial changes in estimated a priori probabilities, sensitivities, and specificities were made to correct for significant under- and overestimations of these values by a group of medical experts. The system based on the derived values appears to perform better than the original system. It is concluded that the statistics used in a Bayesian diagnostic system should be derived from a database representative of the patient population for which the system is designed.

Coaxial needles for repeated biopsy sampling

A set of coaxial biopsy needles permits repeated tissue samples through an outer, larger needle that remains in place. The tract can be dilated from 23 to 16 gauge with the use of transfer rods, without loss of the initial position. The technique has been used successfully in six patients.

Gibbs artifact removal in magnetic resonance imaging

Gibbs artifact in magnetic resonance imaging results when band-limited interpolation is used. This is typically done when there are more reconstructed pixels in the phase encoding direction of the image than corresponding phase encoding measurements. Such sampling is effectively an ideal (in a noise sense) low-pass filter which provides a maximal improvement in contrast resolution at the expense of a decrease in spatial resolution. In this paper we demonstrate that an alternate low-pass filter can be used to improve contrast resolution with a loss in spatial resolution and yet not result in Gibbs artifact. We show that the noise performance of this filter can be made to approach that of an ideal filter by properly specifying the number of samples averaged for each phase encoding index.

A decision-driven system to collect the patient history

We have developed a computer-administered history designed to directly interview hospitalized patients with pulmonary disease. A frame-based decision system is used to direct the history and to generate a one- to five-member differential diagnostic list based on this history. This system incorporates a cognitive model of question selection and a Bayesian scoring algorithm. Structures to control the choice of questions are embedded in the diagnostic frames and in a QUERY program that makes the final choice of questions. We have compared the behavior of this decision-driven approach with a history taken using a paper questionnaire. The paper-based history presents 182 questions to every patient and captured 75% of 85 pulmonary diseases in its differential lists. The decision-driven system asks 50.7 +/- 31.0 (mean +/- standard deviation) and captured 74% of 61 pulmonary diseases. Our experience suggests that the use of a computerized diagnostic knowledge base to direct the selection of pertinent questions can substantially reduce the number of questions necessary to collect a diagnostically useful patient history.

A light-guidance system to be used for CT-guided biopsy

We describe a light-guidance system that uses intersecting helium-neon laser beams to provide precise guidance for biopsy approaches from any direction (including compound angles) during CT-guided biopsy of the chest and abdomen. Interactive software provides visualization of the proposed path, indicates the segment of that path that will pass through each section, and displays the settings for the apparatus.

CT detection of occult pneumothorax in head trauma

A prospective evaluation for occult pneumothorax was performed in 25 consecutive patients with serious head trauma by combining a limited chest CT examination with the emergency head CT examination. Of 21 pneumothoraces present in 15 patients, 11 (52%) were found only by chest CT and were not identified clinically or by supine chest radiograph. Because of pending therapeutic measures, chest tubes were placed in nine of the 11 occult pneumothoraces, regardless of the volume. Chest CT proved itself as the most sensitive method for detection of occult pneumothorax, permitting early chest tube placement to prevent transition to a tension pneumothorax during subsequent mechanical ventilation or emergency surgery under general anesthesia.

Lumbar spine: pretest predictability of CT findings

Demographic and symptomatic data gathered from 460 patients referred for lumbosacral CT examinations were analyzed to determine if the prescan probability of normal or abnormal findings could be predicted accurately. We were unable to predict the presence of herniated disk on the basis of patient-supplied data alone. Age was the single most significant predictor of an abnormality and was sharply related to degenerative disease and spinal stenosis.

A randomized trial of intracoronary streptokinase in the treatment of acute myocardial infarction

Fifty patients with acute myocardial infarction were randomly assigned to receive either intracoronary streptokinase or standard (control) therapy within about three hours after the onset of pain. Coronary perfusion was reestablished in 19 of 24 patients receiving streptokinase. Streptokinase alleviated pain (as indicated by differences in subsequent morphine use). The Killip class was significantly improved after therapy with streptokinase, as were changes in radionuclide ejection fraction between Days 1 and 10 in surviving patients (+3.9 vs. -3.0 per cent, P less than 0.01). The echocardiographic wall-motion index also showed greater improvement after streptokinase treatment (P less than 0.01). Streptokinase therapy was associated with rapid evolution of electrocardiographic changes, which were essentially complete within three hours after therapy, but loss of R waves, ST elevation, and development of Q waves in the convalescent period were greater in the control group (P less than 0.01). The time required to reach peak plasma enzyme concentrations was significantly shorter after streptokinase. The incidence of early and late ventricular arrhythmias was not affected by treatment. We conclude that intracoronary streptokinase appears to have a beneficial effect on the early course of acute myocardial infarction.

Percutaneous catheter drainage in intraabdominal fluid collections including infected biliary ducts and gallbladders

Sixty-five abscesses, including 6 infected biliary systems and 15 sterile fluid collections, were treated by percutaneous catheter drainage in 77 febrile patients who were evaluated by computerized tomography or ultrasonography of intraabdominal infection. Percutaneous catheter drainage and systemic antibiotic administration without surgery provided satisfactory control of infection in 52 of 65 abscesses (80 percent). Catheter drainage followed by surgical exploration for abscess control was performed in an additional 5 of 65 abscesses (7 percent). Nine death (14 percent) occurred in the abscess group of 64 patients. In 15 patients, aspirations, Gram stain, and culture of the abnormal fluid collection revealed sterile fluid. Drainage with a single catheter allowed complete resolution in 14 of 15 sterile collections. Surgery was performed electively in one patient with a fistula from a pancreatic pseudocyst in the small bowel. No deaths occurred in the noninfected group of 15 patients, 2 of whom underwent drainage of coexisting abscesses.

Preexamination prediction of radiographic findings

Computerized medical logic has been developed to calculate the patient-specific pretest likelihood of pleural fluid for radiographic examinations. This medical logic was determined by searching the computerized data base for clinical indicants which are found to differ between groups of patients with and without pleural fluid. By using a priori probabilities of pleural fluid and sequential application of Bayes' equation to revise the likelihood according to the presence of significant indicants, patient-specific likelihood were calculated. This medical logic was tested on a group of 591 patients with and without pleural fluid by radiographic evidence. The results indicated a sensitivity of 95% and a specificity of 81%.

Longitudinal angulation in coronary arteriography: apparatus and evaluation

When good visualization of the left coronary artery and proximal branches is difficult, the longitudinally angulated projection has proved useful. An accessory for achieving this angulation with a conventional angiographic table and without sacrificing the advantages of video monitoring and the protection of lead vinyl shielding is described.