Donna McClish

Analyzing a Portion of the ROC Curve

The area under the ROC curve is a common index summarizing the information contained in the curve. When comparing two ROC curves, though, problems arise when interest does not lie in the entire range of false-positive rates (and hence the entire area). Numerical integration is suggested for evaluating the area under a portion of the ROC curve. Variance estimates are derived. The method is applicable for either continuous or rating scale binormal data, from independent or dependent samples. An example is presented which looks at rating scale data of computed tomographic scans of the head with and without concomitant use of clinical history. The areas under the two ROC curves over an a priori range of false- positive rates are examined, as well as the areas under the two curves at a specific point.

Meta-analysis of estrogen therapy in the management of urogenital atrophy in postmenopausal women : Second report of the hormones and urogenital therapy committee

Objective To evaluate the efficacy of estrogen therapy in the treatment of postmenopausal women with symptoms and signs associated with urogenital atrophy, by meta-analysis of available data. Methods We searched the literature (Excerpta Medica, Biosis, MEDLINE, and hand search) for studies published between January 1969 and April 1995. Criteria for inclusion were English-language articles, peer-reviewed original publications, and urogenital atrophy assessed by at least one of the following outcomes: patient symptoms, physician report, pH, or cytologic change. Data had to allow comparison between treated and control groups in controlled trials or an estimated change from baseline in uncontrolled series. Meta-analytic methods were applied separately to controlled clinical trials and uncontrolled studies. Results Of the 77 relevant articles reviewed, nine contained ten randomized controlled trials. Meta-analysis of these using the Stouffer method revealed a statistically significant benefit of estrogen therapy for all outcomes studied. In 54 uncontrolled case series, the patient symptoms were treated by 24 different treatment modalities. All routes of administration appeared to be effective and maximum benefit was obtained between 1 and 3 months after the start of treatment. As expected, the least systemic absorption of estrogen was seen with estriol (administered orally or vaginally), then vaginal estradiol as measured by pretherapy and posttherapy serum estradiol and estrone. Conclusion Estrogen is efficacious in the treatment of urogenital atrophy and low-dose vaginal estradiol preparations are as effective as systemic estrogen therapy in the treatment of urogenital atrophy in postmenopausal women.

Obesity and lower urinary tract function in women: effect of surgically induced weight loss.

OBJECTIVE The subjective and objective effects of massive weight loss on lower urinary tract function in morbidly obese women were examined. STUDY DESIGN Thirteen subjects underwent a comprehensive evaluation of lower urinary tract function before and 1 year after surgically induced weight loss. RESULTS We demonstrated significant improvements in lower urinary tract function after weight loss. Of 12 subjects who complained of incontinence before surgery only three complained of incontinence (p = 0.004) and only one requested treatment after weight loss. Objective and subjective resolution of both stress and urge incontinence was documented. Statistically significant changes were seen in measures of vesical pressure, the magnitude of bladder pressure increases with coughing, bladder-to-urethra pressure transmission with cough, urethral axial mobility, number of incontinence episodes, and the need to use absorptive pads. CONCLUSION Weight reduction is desirable for obese women complaining of urinary incontinence and may obviate the need for further incontinence therapy.

Clinical characteristics and resource utilization of ICU patients: implications for organization of intensive care.

We reviewed the clinical characteristics and resource utilization of 391 medical (M) and 315 surgical (S) ICU patients. In general, MICU patients had more physiologic derangement, as determined by the admission, maximal, and average acute physiology scores (APS). SICU patients had more frequent therapeutic interventions as measured by admission, maximal, and average therapeutic intervention scoring system values. Notably, 40% of MICU and 30% of SICU patients never received any active interventions and were admitted strictly for monitoring purposes.Patients on admission with APS ≤ 10 had markedly shorter ICU stays, with almost 50% less treatment than patients with APS over 10. Fifty-six percent of patients with APS ≤ 10 did not require any active intervention. In contrast, 83% of patients with APS greater than 10 had considerable intensive interventions. These patients required mechanical ventilation, invasive monitoring, and vasoactive drugs more than twice as often as patients with lower APS scores. Consideration should be given, therefore, to the organization of ICUs according to the patients severity of illness.

Combining and comparing area estimates across studies or strata.

A method for combining and comparing medical tests across studies or strata is presented. The area under the receiver operating characteristic (ROC) curve is the parameter of interest to be used for comparison. The combined area is a weighted average of the areas under the curve in each study or stratum. A chi-square test for equality of areas across strata can be used to compare the areas. The power of the test is also explored. The methods presented are simple and require only knowledge of estimates of area and their standard errors. Either parametric or nonparametric estimates of the area can be used. Key words: ROC curve; area under the curve; stratification; power. (Med Decis Making 1992;12:274-279)

The Impact of Age on Utilization of Intensive Care Resources

The impact of age on admission practices and pattern of care were examined in 599 admissions to a medical intensive care unit (MICU) and 290 patients on the conventional medical care divisions of the same hospital. Four age groups were compared: under 55, 55 to 64, 65 to 74, and 75 years of age and over. Severity of illness and prior health were assessed using the Acute Physiology Score (APS) and the Chronic Health Evaluation (CHE) instruments. Resource utilization was assessed using the Therapeutic Intervention Scoring System (TISS) and hospital charges.

Implications of DRG payments for medical intensive care.

Patients in the most prevalent DRGs in a Medical Intensive Care Unit (MICU) were compared with their counterparts who received only routine hospital care on adjusted total hospital costs and length of stay. Costs for both groups were compared with estimated DRG payments under an allpayer system. For patients in three DRGs, measures of severity of illness were examined as predictors of costs. Significant differences between MICU and routine care patients were found in 10 of 13 DRGs studied; intensive care costs were substantially above overall payment rates. The severity of illness measures varied widely in their correlation with costs, depending on DRG and whether the patients were MICU or routine care. These apparent differences in accounting costs may result in hospital decisions to restrict the number of MICU beds. Severity of illness adjustments to DRGs might produce more equitable payments. The most useful measure of severity may differ, however, depending on DRG.

Bladder training in older women with urinary incontinence: relationship between outcome and changes in urodynamic observations.

The purpose of this study was to clarify the mechanism by which bladder training affects urinary incontinence. Urodynamic data and specific urodynamic diagnoses of 108 women with urinary incontinence were compared before and 6 months after treatment with bladder training. Before treatment, 76 women had sphincteric incompetence, 11 had detrusor instability, and 16 had both. After treatment, 33 women no longer fulfilled the urodynamic diagnostic criteria for either sphincter or detrusor dysfunction. Controlling for severity before treatment, the number of incontinent episodes post-treatment was not associated with change in urodynamic diagnosis. Only the first sensation to void, voided volume, compliance, functional urethral length, and flow time showed any significant changes between pre- and post-treatment evaluations; however, none were correlated with change in the number of incontinent episodes. Bladder training does not appear to affect lower tract urodynamic variables or specific urodynamic diagnosis, and it is likely that its mechanism of action reflects adaptive behavioral changes. Physiologic changes not detected with techniques and/or criteria used in this study may still occur.

Using Medicare data to estimate the number of cases missed by a cancer registry: a 3-source capture-recapture model.

Background:Cancer surveillance is essential for assessing patterns of cancer occurrence. State cancer registries do not capture all available cases potentially biasing results. Secondary data may be useful in identifying new cases and estimating the number of cases missed. Objective:We sought to create 2 distinct data sources from Medicare claims to use in combination with registry data as 3 sources for a capture-recapture analysis to estimate the capture rate and bias in capture of a statewide cancer registry. Methods:Data from the Virginia cancer registry (Registry) were merged with Medicare inpatient (Part A) as well as Medicare outpatient and physician claims (Part B) to provide 3 sources to estimate missing cases. A 3-source loglinear model was used to estimate the number of missing cancer cases for breast, lung, colorectal, and prostate cancer. Models included main effects and interactions. Additional analysis looked at the effect of demographic and comorbidity variables. Results:Loglinear models demonstrated mostly positive dependence between the 3 sources, implying that 2-source models would underestimate missing cases and overestimate capture rates. Using capture-recapture estimates of total number of cancer cases as the denominator, capture rates for Registry ranged from 59% (colorectal) to 74% (lung). When the aggregate of cases found by either Medicare or Registry were used the capture rates ranged from 74% (prostate) to 89% (breast). Further analysis indicated that capture rates differed by demographic characteristics. Conclusion:We conclude that Medicare claims are useful to supplement a Registry, estimate the number of missing cases, and assess bias in capture.

Effect of a Home-Based Palliative Care Program on Healthcare Use and Costs.

To evaluate the nonclinical outcomes of a proactive palliative care program funded and operated by a health system for Medicare Advantage plan beneficiaries.