A Proposal for an Out-of-Range Glycemic Population Health Safety Measure for Older Adults With Diabetes

OBJECTIVE

To evaluate patient-level glycemic control and facility variation of a proposed out-of-range (OOR) measure (overtreatment [OT] [HbA_1c <7% (53 mmol/mol)] or undertreatment [UT] [>9% (75 mmol/mol)]) compared with the standard measure (SM) (HbA_1c <8% [64 mmol/mol]) in high-risk older adults.

RESEARCH DESIGN AND METHODS

Veterans Health Administration patients ≥65 years of age in 2012 who were taking antihyperglycemic agents in 2013 were identified. Patient-level rates and facility-level rates/rankings were calculated by age and comorbid illness burden.

RESULTS

We identified 303,097 patients who were taking antiglycemic agents other than metformin only. The study population comprised 193,689 patients with at least one significant medical, neurological, or mental health condition; 98.2% were taking a sulfonylurea and/or insulin; 55.2% were aged 65-75 years; and 44.8% were aged >75 years. The 47.4% of patients 65-75 years met the OOR measure (33.4% OT, 14% UT), and 65.7% met the SM. For patients aged >75 years, rates were 48.1% for OOR (39.2% OT; 8.9% UT) and 73.2% for SM. Facility-level rates for OOR for patients aged 65-75 years ranged from 33.7 to 60.4% (median 47.4%), with a strong inverse correlation (ρ = -0.41) between SM and OOR performance rankings. Among the best-performing 20% facilities on the SM, 14 of 28 ranked in the worst-performing 20% on the OOR measure; 12 of 27 of the worst-performing 20% facilities on the SM ranked in the best-performing 20% on the OOR measure.

CONCLUSIONS

Facility rankings that are based on an SM (potential benefits) and OOR measure (potential risks) differ substantially. An OOR for high-risk populations can focus quality improvement on individual patient evaluation to reduce the risk for short-term harms.

Chronic stress and Rosiglitazone increase indices of vascular stiffness in male rats

Prolonged and/or frequent exposure to psychological stress responses may lead to deterioration of organs and tissues, predisposing to disease. In agreement with this, chronic psychosocial stress is linked to greater cardiovascular risk, including increased incidence of atherosclerosis, myocardial ischemia, coronary heart disease, and death. Thus the association between stress and cardiovascular dysfunction represents an important node for therapeutic intervention in cardiovascular disease. Here we report that 2weeks of chronic variable stress (CVS) increased indices of vascular stiffness, including increased collagen deposition in the aortic adventitia and increased resting pulse pressure, in male rats. Thus CVS may represent a useful rodent model for stress-associated CVD, especially for aging populations for which widening pulse pressure is a well-known risk factor. Additionally, we report that the thiazolidinedione Rosiglitazone (RSG) blunts chronic stress-associated increases in circulating corticosterone. Despite this, RSG was not protective against adverse cardiovascular outcomes associated with chronic stress. Rather RSG itself is associated with increased pulse pressure, and this is exacerbated by chronic stress-highlighting that chronic stress may represent an additional contributor to RSG-associated cardiovascular risk.

Variability in estimated glomerular filtration rate values is a risk factor in chronic kidney disease progression among patients with diabetes

Background

It is unknown whether variability of estimated Glomerular Filtration Rate (eGFR) is a risk factor for dialysis or death in patients with chronic kidney disease (CKD). This study aimed to evaluate variability of estimated Glomerular Filtration Rate (eGFR) as a risk factor for dialysis or death to facilitate optimum care among high risk patients.

Methods

A longitudinal retrospective cohort study of 70,598 Veterans Health Administration veteran patients with diabetes and CKD (stage 3–4) in 2000 with up to 5 years of follow-up. VHA and Medicare files were linked to derive study variables. We used Cox proportional hazards models to evaluate association between time to initial dialysis/death and key independent variables: time-varying eGFR variability (measured by standard deviation (SD)) and eGFR means and slopes while adjusting for prior hospitalizations, and comorbidities.

Results

There were 76.7% older than 65 years, 97.5% men, and 81.9% Whites. Patients were largely in early stage 3 (61.2%), followed by late stage 3 (28.9%), and stage 4 (9.9%); 29.1%, 46.8%, and 73.3%, respectively, died or had dialysis during the follow-up. eGFR SDs (median: 5.8, 5.1, and 4.0 ml/min/1.73 m² ) and means (median: 54.1, 41.0, 27.2 ml/min/1.73 m²) from all two-year moving intervals decreased as CKD advanced; eGFR variability (relative to the mean) increased when CKD progressed (median coefficient of variation: 10.9, 12.8, and 15.4). Cox regressions revealed that one unit increase in a patient’s standard deviation of eGFRs from prior two years was significantly associated with about 7% increase in risk of dialysis/death in the current year, similarly in all three CKD stages. This was after adjusting for concurrent means and slopes of eGFRs, demographics, prior hospitalization, and comorbidities. For example, the hazard of dialysis/death increased by 7.2% (hazard ratio:1.072; 95% CI = 1.067, 1.080) in early stage 3.

Conclusion

eGFR variability was independently associated with elevated risk of dialysis/death even after controlling for eGFR means and slopes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0025-5) contains supplementary material, which is available to authorized users.

Assessing potential glycemic overtreatment in persons at hypoglycemic risk

IMPORTANCE

Although serious hypoglycemia is a common adverse drug event in ambulatory care, current performance measures do not assess potential overtreatment.

OBJECTIVE

To identify high-risk patients who had evidence of intensive glycemic management and thus were at risk for serious hypoglycemia.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of patients in the Veterans Health Administration receiving insulin and/or sulfonylureas in 2009.

MAIN OUTCOMES AND MEASURES

Intensive control was defined as the last hemoglobin A1c (HbA1c) measured in 2009 that was less than 6.0%, less than 6.5%, or less than 7.0%. The primary outcome measure was an HbA1c less than 7.0% in patients who were aged 75 years or older who had a serum creatinine value greater than 2.0 mg/dL or had a diagnosis of cognitive impairment or dementia. We also assessed the rates in patients with other significant medical, neurologic, or mental comorbid illness. Variation in rates of possible glycemic overtreatment was evaluated among 139 Veterans Health Administration facilities grouped within 21 Veteran Integrated Service Networks.

RESULTS

There were 652,378 patients who received insulin and/or a sulfonylurea with an HbA1c test result. Fifty percent received sulfonylurea therapy without insulin; the remainder received insulin therapy. We identified 205,857 patients (31.5%) as the denominator for the primary outcome measure; 11.3% had a last HbA1c value less than 6.0%, 28.6% less than 6.5%, and 50.0% less than 7.0%. Variation in rates by Veterans Integrated Service Network facility ranged 8.5% to 14.3%, 24.7% to 32.7%, and 46.2% to 53.4% for HbA1c less than 6.0%, less than 6.5%, and less than 7.0%, respectively. The magnitude of variation by facility was larger, with overtreatment rates ranging from 6.1% to 23.0%, 20.4% to 45.9%, and 39.7% to 65.0% for HbA1c less than 6.0%, less than 6.5%, and less than 7.0%, respectively. The maximum rate was nearly 4-fold compared with the minimum rates for HbA1c less than 6.0%, followed by 2.25-fold for HbA1c less than 6.5% and less than 2-fold for HbA1c less than 7.0%. When comorbid conditions were included, 430,178 patients (65.9%) were identified as high risk. Rates of overtreatment were 10.1% for HbA1c less than 6.0%, 25.2% for less than 6.5%, and 44.3% for less than 7.0%.

CONCLUSIONS AND RELEVANCE

Patients with risk factors for serious hypoglycemia represent a large subset of individuals receiving hypoglycemic agents; approximately one-half had evidence of intensive treatment. A patient safety indicator derived from administrative data can identify high-risk patients for whom reevaluation of glycemic management may be appropriate, consistent with meaningful use criteria for electronic medical records.

A clinical action measure to assess glycemic management in the 65-74 year old veteran population

OBJECTIVES

To evaluate the effect of including of clinical actions within 6 months of a glycosylated hemoglobin (HbA1c) level greater than 8% upon measure adherence (pass rates) and to assess the association between patient factors and the likelihood of not passing.

SETTING

Veterans Health Administration.

DESIGN

Retrospective cohort study for FY2002 to FY2004.

PARTICIPANTS

One hundred fifty-three thousand one hundred thirty-two veterans aged 65-74 with diabetes mellitus not taking insulin; 99% were male and 86% white.

MEASUREMENTS

The clinical action measure included three categories: (a) initial pass (index HbA1c < 8%); (b) modified pass (index HbA1c ≥ 8%), and the hierarchical occurrence of one of the following events within 6 months after date of index HbA1c: subsequent HbA1c < 8%, being started on insulin (100% weight), new oral medication (50% weight), care in a diabetes mellitus-related clinic (25% weight); and (c) failure (no category met or HbA1c > 9%). Multinomial logistic regression models were used to evaluate associations between participant factors and the likelihood of not passing initially.

RESULTS

Most (82.6%) or the participants had an index HbA1c of less than 8%, and 10.6% were in the modified pass group. The failure rate (17.4%) fell to 6.8% when actions were weighted equally and to 9.4% using different weights. Veterans who are African American (odds ratios (ORs) = 1.43 and 1.44), unmarried (ORs = 1.19 and 1.24), poor (ORs = 1.36 and 1.17), or taking two or more oral antihyperglycemic agents (ORs = 2.61 and 3.72) were significantly more likely to be in the modified pass and failure groups, respectively.

CONCLUSION

Most veterans with an initial HbA1c of 8% or greater had clinical actions within 6 months. A measure that incorporates multiple treatment options, including education and nutrition, could be of benefit by encouraging dialogue of such options between patients and clinicians.

Hidden complexities in assessment of glycemic outcomes: are quality rankings aligned with treatment?

OBJECTIVE

To evaluate facility rankings in achieving <7% A1C levels based on the complexity of glycemic treatment regimens using threshold and continuous measures.

RESEARCH DESIGN AND METHODS

We conducted a retrospective administrative data analysis of Veterans Health Administration Medical Centers in 2003-2004. Eligible patients were identified using National Committee for Quality Assurance (NCQA) measure specifications. A complex glycemic regimen (CGR) was defined as receipt of insulin or three oral agents. Facilities were ranked using five ordinal categories based up both z score distribution and statistical significance (P < 0.05). Rankings using the NCQA definition were compared with a subset receiving CGRs using both a <7% threshold and a continuous measure awarding proportional credit for values between 7.9 and <7.0%. Ranking correlation was assessed using the Spearman correlation coefficient.

RESULTS

A total of 203,302 patients (mean age 55.2 years) were identified from 127 facilities (range 480-5,411, mean 1,601); 26.7% (17.9-35.2%) were receiving CGRs, including 22.0% receiving insulin. Mean A1C and percent achieving A1C <7% were 7.48 and 48% overall and 8.32 and 24.8% for those receiving CGRs using the threshold measure; proportion achieved was 60.1 and 37.2%, respectively, using the continuous measure. Rank correlation between the overall and CGR subset was 0.61; 8 of 24 of the highest or lowest ranked facilities changed to nonsignificance status; an additional five sites changed rankings.

CONCLUSIONS

Facility rankings in achieving the NCQA <7% measure as specified differ markedly from rankings using the CGR subset. Measurement for public reporting or payment should stratify rankings by CGR. A continuous measure may better align incentives with treatment intensity.

Patient complexity in quality comparisons for glycemic control: an observational study

Background

Patient complexity is not incorporated into quality of care comparisons for glycemic control. We developed a method to adjust hemoglobin A1c levels for patient characteristics that reflect complexity, and examined the effect of using adjusted A1c values on quality comparisons.

Methods

This cross-sectional observational study used 1999 national VA (US Department of Veterans Affairs) pharmacy, inpatient and outpatient utilization, and laboratory data on diabetic veterans. We adjusted individual A1c levels for available domains of complexity: age, social support (marital status), comorbid illnesses, and severity of disease (insulin use). We used adjusted A1c values to generate VA medical center level performance measures, and compared medical center ranks using adjusted versus unadjusted A1c levels across several thresholds of A1c (8.0%, 8.5%, 9.0%, and 9.5%).

Results

The adjustment model had R² = 8.3% with stable parameter estimates on thirty random 50% resamples. Adjustment for patient complexity resulted in the greatest rank differences in the best and worst performing deciles, with similar patterns across all tested thresholds.

Conclusion

Adjustment for complexity resulted in large differences in identified best and worst performers at all tested thresholds. Current performance measures of glycemic control may not be reliably identifying quality problems, and tying reimbursements to such measures may compromise the care of complex patients.

Risk of stroke, heart attack, and diabetes complications among veterans with spinal cord injury

OBJECTIVES

To compare the rates of diabetes and macrovascular conditions in veterans with spinal cord injury (SCI) and to examine variations by patient-level demographic, socioeconomic, access, and health status factors.

DESIGN

A retrospective analysis. Diabetes status was classified by merging with diabetes epidemiology cohort using a validated algorithm. Chi-square tests and logistic regressions used to compare rates in macro- and microvascular conditions in veterans with and without diabetes.

SETTING

Veteran Health Administration clinic users in fiscal year (FY) 1999 to FY 2001.

PARTICIPANTS

SCI patients (N=8769) with diabetes (n=1333), in FY 2000, identified through the SCI registry.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Macrovascular and microvascular conditions in the next year (February 2001). Derived from International Statistical Classification of Diseases, 9th Revision, Clinical Modification, codes in the patient treatment files.

RESULTS

Overall, 15% of SCI veterans were identified with diabetes but this was an underestimate due to high mortality (8%). Among SCI veterans with diabetes, 49% had at least one macrovascular condition and 54% had microvascular conditions compared with 24% and 25% of those without diabetes (P<.001).

CONCLUSIONS

Our study highlights the highly significant relationship between diabetes and macro- and microvascular conditions in veterans with SCI. Neurologic deficit combined with increased insulin resistance has a greater macrovascular impact on SCI veterans than on those who do not have diabetes. Increasing age and physical comorbidities compound the problem.

Three-Dimensional Mathematical Model for Deformation of Human Fasciae in Manual Therapy

Context: Although mathematical models have been developed for the bony movement occurring during chiropractic manipulation, such models are not available for soft tissue motion.

Objective: To develop a three-dimensional mathematical model for exploring the relationship between mechanical forces and deformation of human fasciae in manual therapy using a finite deformation theory.

Methods: The predicted stresses required to produce plastic deformation were evaluated for a volunteer subject's fascia lata, plantar fascia, and superficial nasal fascia. These stresses were then compared with previous experimental findings for plastic deformation in dense connective tissues. Using the three-dimensional mathematical model, the authors determined the changing amounts of compression and shear produced in fascial tissue during 20 seconds of manual therapy.

Results: The three-dimensional model's equations revealed that very large forces, outside the normal physiologic range, are required to produce even 1% compression and 1% shear in fascia lata and plantar fascia. Such large forces are not required to produce substantial compression and shear in superficial nasal fascia, however.

Conclusion: The palpable sensations of tissue release that are often reported by osteopathic physicians and other manual therapists cannot be due to deformations produced in the firm tissues of plantar fascia and fascia lata. However, palpable tissue release could result from deformation in softer tissues, such as superficial nasal fascia.

Survival benefit of nephrologic care in patients with diabetes mellitus and chronic kidney disease

BACKGROUND

The association of nephrologic care and survival in patients with diabetes mellitus and chronic kidney disease is unknown.

METHODS

Using data from 1997 to 2000, we conducted a retrospective cohort study of Veterans Health Administration clinic users having diabetes mellitus and stage 3 or 4 chronic kidney disease. The baseline period was 12 months and median follow-up was 19.3 months. Degree of consistency of visits to a nephrologist, defined as the number of calendar quarters in which there was 1 visit or more (range, 0-4 quarters), and covariates were calculated from the baseline period. The outcome measure was dialysis-free death.

RESULTS

Of 39,031 patients, 70.0%, 22.4%, and 7.6% had early stage 3, late stage 3, and stage 4 chronic kidney disease, respectively, and 3.1%, 9.5%, and 28.2%, respectively, visited a nephrologist. Dialysis-free mortality rates were 9.6, 14.1, and 19.4, respectively, per 100 person-years. More calendar quarters with visits to a nephrologist were associated with lower mortality: adjusted hazard ratios were 0.80 (95% confidence interval, 0.67-0.97), 0.68 (95% confidence interval, 0.55-0.86), and 0.45 (95% confidence interval, 0.32-0.63), respectively, when the groups having 2, 3, and 4 visits were compared with those who had no visits. One visit only was not associated with a difference in mortality when compared with no visits (adjusted hazard ratio,1.02; 95% confidence interval, 0.89-1.16).

CONCLUSIONS

The consistency of outpatient nephrologic care was independently associated in a graded fashion with lower risk of deaths in patients with diabetes and moderately severe to severe chronic kidney disease. However, only a minority of patients had any visits to a nephrologist.

Should mitigating comorbidities be considered in assessing healthcare plan performance in achieving optimal glycemic control?

BACKGROUND

Whether a public reporting measure for glycosylated hemoglobin (A1C) of less than 7% should apply to all persons with diabetes mellitus is a matter of ongoing controversy.

OBJECTIVE

To evaluate the effect of excluding persons with major medical or mental health conditions on assessment of healthcare system performance in achieving an A1C level of less than 7%.

DESIGN AND SETTING

Retrospective longitudinal administrative data analysis from 144 Veterans Health Administration medical centers.

SUBJECTS

Veterans with diabetes mellitus younger than 65 years who were users of Veterans Health Administration healthcare in fiscal years 1999 and 2000. MAJOR OUTCOME VARIABLES: The proportions, 5-year mortality, and glycemic control of individuals with and without major comorbid conditions, as well as changes in league table rankings of facilities achieving an A1C threshold of less than 7% with and without the inclusion of seriously ill individuals.

RESULTS

There were 220 922 subjects identified from 144 facilities. We identified 75 296 individuals (mean +/- SD facility range of excluded individuals, 33.3% +/- 5.3%) with conditions that would decrease the benefits or increase risks of glycemic control. The 5-year unadjusted mortality was 36.0% in 48 001 subjects (21.7%) excluded for major medical or neurological conditions, 14.9% in 17 515 subjects (7.9%) excluded for major mental health conditions, and 16.5% in 9780 subjects (4.4%) excluded for 2 or more other serious comorbid medical or psychological conditions, compared with 8.8% in the remaining subjects. A comparison of industry league table rankings indicated that 20% of the best and worse facilities changed 1 decile when ranking using exclusion criteria.

CONCLUSION

One in 3 veterans has comorbid conditions that would increase the risks or decrease the benefits of intensive glycemic control. We propose that a public reporting measure for A1C of less than 7% be subjected to exclusion criteria rather than be applied to all persons with diabetes mellitus.

Facility variation in utilization of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in patients with diabetes mellitus and chronic kidney disease

OBJECTIVE

To evaluate facility-level variation in prescription rates of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) medications for patients with diabetes mellitus (DM) and chronic kidney disease (CKD).

STUDY DESIGN

Retrospective database analysis from 143 Veterans Health Administration facilities.

METHODS

Subjects with DM aged 18 to 75 years were identified as having stage 2-4 CKD using estimated glomerular filtration rate (eGFR) based on an index eGFR in 1999 and a subsequent eGFR 90-365 days later. Whether ACEI/ARB medications were prescribed within 1 year after the index eGFR was determined. Variation in facility-level rates was evaluated separately for subjects age <65 years and 65 to 75 years from facilities with more than 50 subjects per age group.

RESULTS

A total of 103 853 subjects had stage 2 CKD; 51 728, stage 3; and 3233, stage 4. However, 25% of facilities had fewer than 50 patients age <65 years with either stage 3 or 4 CKD. The median (range) facility-level prescription rates of ACEI/ARB for stage 2 and combined stage 3-4 CKD were 58.5% (44.3%-71.2%) and 73.3% (51.7%-84.6%), respectively, for subjects age <65 years; and 56.5% (38.1%-71.4%) and 68.4% (51.6%-80.1%), respectively, for subjects aged 65 to 75 years. Spearman rank correlation between facility rankings by age group was 0.72 for stage 2 (139 facilities) and 0.49 for stage 3-4 (111 facilities) (P < .001).

CONCLUSION

Although ascertainment of prescription rates of ACEI/ARB to CKD patients is feasible using electronic health records, small sample size at the healthcare-system level preclude their utility for public reporting.

Impact of self-reported patient characteristics upon assessment of glycemic control in the Veterans Health Administration

OBJECTIVE

The purpose of this article was to evaluate the impact of self-reported patient factors on quality assessment of Veterans Health Administration medical centers in achieving glycemic control.

RESEARCH DESIGN AND METHODS

We linked survey data and administrative records for veterans who self-reported diabetes on a 1999 national weighted survey. Linear regression models were used to adjust A1C levels in fiscal year 2000 for socioeconomic status (education level, employment, and concerns of having enough food), social support (marital status and living alone), health behaviors (smoking, alcohol use, and exercise level), physical and mental health status, BMI, and diabetes duration. Medical centers were ranked by deciles, with and without adjustment for patient characteristics, on proportions of patients achieving A1C <7 or <8%.

RESULTS

There was substantial medical center level variation in patient characteristics of the 56,740 individuals from 105 centers, e.g., grade school education (mean 15.3% [range 2.3-32.7%]), being retired (38.3% [19.9-59.7%]) or married (65.2% [43.7-77.8%]), food insufficiency (13.9% [7.2-24.6%]), and no reported exercise (43.2% [31.1-53.6%]). The final model had an R(2) of 7.8%. The Spearman rank coefficient comparing the thresholds adjusted only for age and sex to the full model was 0.71 for <7% and 0.64 for <8% (P < 0.0001). After risk adjustment, 4 of the 11 best-performing centers changed at least two deciles for the <7% threshold, and 2 of 11 changed two deciles for the <8% threshold.

CONCLUSIONS

Adjustment for patient self-reported socioeconomic status and health impacts medical center rankings for glycemic control, suggesting the need for risk adjustment to assure valid inferences about quality.

Failure of ICD-9-CM codes to identify patients with comorbid chronic kidney disease in diabetes

OBJECTIVE

To determine prevalence of chronic kidney disease (CKD) in patients with diabetes, and accuracy of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes to identify such patients.

DATA SOURCES/STUDY SETTING

Secondary data from 1999 to 2000. We linked all inpatient and outpatient administrative and clinical records of U.S. veterans with diabetes dually enrolled in Medicare and the Veterans Administration (VA) health care systems.

STUDY DESIGN

We used a cross-sectional, observational design to determine the sensitivity and specificity of renal-related ICD-9-CM diagnosis codes in identifying individuals with chronic kidney disease.

DATA COLLECTION/EXTRACTION METHODS

We estimated glomerular filtration rate (eGFR) from serum creatinine and defined CKD as Stage 3, 4, or 5 CKD by eGFR criterion according to the Kidney Disease Outcomes Quality Initiative guidelines. Renal-related ICD-9-CM codes were grouped by algorithm.

PRINCIPAL FINDINGS

Prevalence of CKD was 31.6 percent in the veteran sample with diabetes. Depending on the detail of the algorithm, only 20.2 to 42.4 percent of individuals with CKD received a renal-related diagnosis code in either VA or Medicare records over 1 year. Specificity of renal codes for CKD ranged from 93.2 to 99.4 percent. Patients hospitalized in VA facilities were slightly more likely to be correctly coded for CKD than patients hospitalized in facilities reimbursed by Medicare (OR 5.4 versus 4.1, p=.0330)

CONCLUSIONS

CKD is a common comorbidity for patients with diabetes in the VA system. Diagnosis codes in administrative records from Medicare and VA systems are insensitive, but specific markers for patients with CKD.

Diabetes healthcare quality report cards: how accurate are the grades?

OBJECTIVE

To evaluate the accuracy and precision of random sampling in identifying healthcare system outliers in diabetes performance measures.

STUDY DESIGN

Cross-sectional analysis of 79 Veterans Health Administration facilities serving 250 317 patients with diabetes mellitus between October 1, 1999, and September 30, 2000.

METHODS

Primary outcome measures were poor glycosylated hemoglobin (A1C) control and good low-density lipoprotein cholesterol (LDL-C) and blood pressure (BP) control. Facility performance for each measure was calculated using 150 separate random samples and was compared with results using the bootstrap method as the criterion standard for determining outlier status (defined as a >/=5% difference from the mean, within the 10th or 90th percentile, or >/=2 SDs from the mean).

RESULTS

The study population was largely male (97.4%), with 54.0% of subjects being 65 years or older. The facility-level mean performances were 22.8% for poor A1C control, 53.1% for good LDL-C control, and 55.3% for good BP control. Comparing the random sampling method with the bootstrap method, the sensitivity ranged between 0.64 and 0.83 for the 3 outcome measures, positive predictive values ranged between 0.55 and 0.88, and specificity and negative predictive values ranged between 0.88 and 0.99.

CONCLUSIONS

The specificity and negative predictive value of the random sampling method in identifying nonoutliers in performance were generally high, while its sensitivity and positive predictive value were moderate. The use of random sampling to determine performance for individual outcome measures may be most appropriate for internal quality improvement rather than for public reporting.

Postural stability index is a more valid measure of stability than equilibrium score

Researchers, therapists, and physicians often use equilibrium score (ES) from the Sensory Organization Test, a key test in the NeuroCom EquiTest System (a dynamic posturography system) to assess stability. ES reflects the overall coordination of the visual, proprioceptive, and vestibular systems for maintaining standing posture. In our earlier article, we proposed a new measure of anterior-posterior (A-P) postural stability called the Postural Stability Index (PSI), which accounts for more biomechanical aspects than ES. This article showed that PSI provides a clinically important adjunct to ES. In the present article, we show that PSI can provide an acceptable index even if a person falls during the trial, whereas ES assigns a zero score for any fall. We also show that PSI decreases as ankle stiffness increases, which is intuitive, while ES exhibits the opposite behavior. Ankle stiffness is generally recognized as an indicator of postural stability. These results suggest that PSI is a more valid measure of A-P stability than ES.

Measures of postural stability

Dynamic posturography has become an important tool for understanding standing balance in clinical settings. A key test in the NeuroCom International (Clackamas, Oregon) dynamic posturography system, the Sensory Organization Test (SOT), provides information about the integration of multiple components of balance. The SOT test leads to an outcome measure called the "equilibrium score" (ES), which reflects the overall coordination of the visual, proprioceptive, and vestibular systems for maintaining standing posture. Researchers, therapists, and physicians often use the ES from the SOT as a clinically relevant measure of standing balance. We discuss here the formula used for evaluating the ES and propose an additional measure of postural stability, called the Postural Stability Index (PSI), that accounts for shear force and individual anthropomorphic measures. We propose that this new measure provides a clinically important adjunct to the current SOT and can be calculated from data already collected by the NeuroCom forceplate during the SOT.