Dialysis decision-making process by Chinese American patients at an urban, academic medical center: a retrospective chart review.

BACKGROUND: Clinical practice guidelines emphasize shared decision-making for kidney replacement treatment, yet little is known about the influence of cultural differences on that process. We undertook a retrospective chart review to explore the process and timing of dialysis decision making and initiation in Chinese American patients to provide quality kidney care for this population. DESIGN: Participants received outpatient care at Tufts Medical Center and dialysis at Dialysis Clinic, Inc. Boston or Somerville, MA from 2001-2021. Clinic chart review sourced demographic, clinical, and end-of-life care information from 180 participants (82 Chinese American, 98 other) from stage 4 chronic kidney disease (CKD) and dialysis initiation. RESULTS: Chinese American participants were older (mean 70 vs. 59, p < 0.0001), less likely to speak English (12% vs. 87%, p < 0.0001), and used interpreter services more (80% vs. 11%, p < 0.0001). Chinese American participants had more visits (median 14 vs. 10, p = 0.005); were more often accompanied by family members (75% vs. 40%, p < 0.001); and had significantly lower rates of healthcare proxy documentation (35% vs. 55%, p = 0.006). There was no statistical difference in months between first CKD 4 visit and first dialysis. Both groups started dialysis at the same average eGFR and with similar rates of permanent dialysis access. Chinese American participants had significantly lower serum albumin at dialysis initiation (mean 3.3 g/dL vs 3.7 g/dL, p = 0.0003). Documentation reflected a low number of conversations about non-dialytic care, end-of-life planning, or palliative care in both groups across all visits. CONCLUSION: The time between CKD 4 and dialysis initiation was the same in both groups, suggesting a similar overall outcome of care. Chart documentation suggests that Chinese American participants had a significantly higher number of visits with nephrologists where discussion about dialysis was noted and were more likely to have a family member present at the visit. Fewer Chinese American participants completed healthcare proxies. Among all study participants, healthcare proxy, code status, and palliative care discussions were reported less frequently than expected. These findings highlight opportunities for collaboration between palliative care clinicians and nephrologists.

Conceptual Framework for Patient-Reported Outcome Measures in Clinical Trials of Skeletal Muscle Cramping Experienced in Dialysis: A Kidney Health Initiative Workgroup Report.

Skeletal muscle cramping is a common and bothersome symptom for patients on maintenance dialysis therapy, regardless of modality, and it has not been prioritized for innovative assessments or treatments. Research to prevent or treat skeletal muscle cramping in patients receiving dialysis is hindered by poorly understood pathophysiology, lack of an accepted definition, and the absence of a standardized measurement method. The Kidney Health Initiative, a public-private partnership between the American Society of Nephrology and US Food and Drug Administration, convened a multidisciplinary workgroup to define a set of patient-reported outcome measures for use in clinical trials to test the effect of new dialysis devices, new KRTs, lifestyle/behavioral modifications, and medications on skeletal muscle cramping. Upon determining that foundational work was necessary, the workgroup undertook a multistep process to elicit concepts central to developing the basis for demonstrating content validity of candidate patient-reported outcome measures for skeletal muscle cramping in patients on dialysis. The workgroup sought to (1) create an accepted, patient-endorsed definition for skeletal muscle cramping that applies to all dialysis modalities, (2) construct a conceptual model for developing and evaluating a skeletal muscle cramping-specific patient-reported outcome measure, and (3) identify potential questions from existing patient-reported outcome measures that could be modified or adapted and subsequently tested in the dialysis population. We report the results of the workgroup's efforts, provide our recommendations, and issue a call to action to address the gaps in knowledge and research needs we identified. These action steps are urgently needed to quantify skeletal muscle cramping burden, assess the effect, and measure meaningful changes of new interventions to improve the experience of patients receiving dialysis and suffering from skeletal muscle cramping.

Randomized Controlled Trials 3: Measurement and Analysis of Patient-Reported Outcomes.

The study of patient-reported outcomes, now common in clinical research, had its origins in social and scientific developments during the latter twentieth century. Patient-reported outcomes comprise functional and health status, health-related quality of life, and quality of life. The terms overlap and are used inconsistently, and these terms should be distinguished from expressions of preference regarding health states. Regulatory standards from the USA and European Union provide some guidance regarding reporting of patient-reported outcomes. Determining that patient-reported outcomes measurement is important depends in part on the balance between subjective and objective outcomes of the health problem under study. Instrument selection depends to a large extent on practical considerations. A number of instruments can be identified that are frequently used in particular clinical situations. The domain coverage of commonly used generic short forms varies substantially. Individualized measurement of quality of life is possible, but resource intensive. Focus groups are useful, not only for scale development but also to confirm the appropriateness of existing instruments.Under classical test theory, validity and reliability are the critical characteristics of tests. Under item response theory, validity remains central, but the focus moves from the reliability of scales to the relative levels of traits in individuals and items' relative difficulty. Plans for clinical studies should include an explicit model of the relationship of patient-reported outcomes to other parameters, as well as define the magnitude of difference in patient-reported outcomes that will be considered important. It is particularly important to minimize missing patient-reported outcome data; to a limited extent, a variety of statistical techniques can mitigate the consequences of missing data.

Long-term Clinical Outcomes Among Responders and Nonresponders to the In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) Survey.

RATIONALE & OBJECTIVE: The In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey, introduced into the End-Stage Renal Disease Quality Incentive Program, is the only patient-reported outcome currently used for value-based reimbursement in dialysis. Current response rates are ∼30% and differences in long-term clinical outcomes between survey responders and nonresponders are unknown. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Patients from all Dialysis Clinic Incorporated facilities from across the United States who met survey eligibility (aged ≥18 years and had been treated at their facility for at least 3 months). EXPOSURES: Patient-level demographic, clinical, and treatment-related characteristics. OUTCOMES: Mortality, all-cause hospitalization, and kidney transplantation. ANALYTICAL APPROACH: Time-to-event analyses using competing-risks models. Sensitivity analyses performed after multiple imputation for missing covariate data. RESULTS: Among 10,395 eligible patients, 3,794 (36%) responded to the survey. During a median follow-up of 33 months, 4,588 patients died, 7,638 patients were hospitalized at least once, and 789 patients received a transplant. In multivariable models, survey response was associated with lower mortality (subdistribution hazard ratio [sHR], 0.80; 95% CI, 0.75-0.86) and hospitalization (sHR, 0.94; 95% CI, 0.89-0.99) and higher likelihood for a kidney transplant (sHR, 1.27; 95% CI, 1.10-1.46). Results were consistent across sensitivity analyses after multiple imputation for missing covariates. LIMITATIONS: Small amount of missing covariate data, baseline covariate data assigned at the first month of the 3-month survey administration period, reasons for nonresponse unknown. CONCLUSIONS: Response to the ICH CAHPS survey is associated with lower risk for mortality and hospitalization and higher likelihood for kidney transplantation. These findings suggest that survey responders are healthier than nonresponders, emphasizing the need for caution when interpreting facility-level survey results to inform quality improvement and public policy efforts and the critical need to better capture patient-reported outcomes from more vulnerable patients.

Using Patient Experience Survey Data to Improve In-Center Hemodialysis Care: A Practical Review.

Patient experience is an integral aspect of the care we deliver to our dialysis patients. Standardized evaluation of patient experience with in-center hemodialysis started in the United States in 2012 with the In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey. Over time there have been a few changes to this survey, how it is administered, and how it fits within the Centers for Medicare & Medicaid Services End-Stage Renal Disease Quality Incentive Program. Although the importance of this survey has been growing, knowledge of this survey among nephrologists has lagged. We provide a review of the survey development and how its use has evolved since 2012. We discuss in detail research done on this survey to date, including survey psychometric evaluation. We highlight gaps in our knowledge that need further research and end with general recommendations to improve patient experience within hemodialysis facilities, which we believe is a worthy goal for all members of the dialysis team.

Improving CKD-Specific Patient-Reported Measures of Health-Related Quality of Life.

BACKGROUND: Patient-reported outcome measures that are more practical and clinically useful are needed for patients with CKD. We compared a new CKD-specific quality-of-life impact scale (CKD-QOL) with currently used measures. METHODS: Patients (n=485) in different treatment groups (nondialysis stages 3-5, on dialysis, or post-transplant) completed the kidney-specific CKD-QOL and Kidney Disease Quality of Life-36 (KDQOL-36) forms and the generic SF-12 Health Survey at baseline and 3 months. New items summarizing quality of life (QOL) impact attributed to CKD across six QOL domains yielded single impact scores from a six-item static (fixed-length) form and from computerized adaptive tests (CATs) with three to six items. Validity tests compared the CKD-QOL, KDQOL-36 (Burden, Effects, and Symptoms/Problems subscales), and generic SF-12 measures across groups in four tests of clinical status and clinician assessment of change (CKD-specific tests), and number of comorbidities. ANOVA was used to test for group mean differences, variances in each measure explained by groups, and relative validity (RV) in comparison with the referent KDQOL-36 Burden subscale. RESULTS: KDQOL-36 and CKD-QOL measures generally discriminated better than generic SF-12v2 measures. The pattern of variances across CKD-specific tests comparing validity favored CKD-QOL two-fold over KDQOL-36. Two RV test results confirmed CKD-QOL improvements over the referent KDQOL scale. Results for static and CAT CKD-QOL forms were similar. SF-12 Physical and KDQOL-36 Symptoms scores worsened with increasing comorbid condition counts. CONCLUSIONS: Overall, compared with the KDQOL-36, the new approach to summarizing CKD-specific QOL impact performed better across multiple tests of validity. CAT surveys were more efficient than static surveys.

Hemodialysis patient characteristics associated with better experience as measured by the In-center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey.

BACKGROUND: Patient experience in hemodialysis (HD) is measured twice yearly in all in-center HD patients in the United States using the In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey. Survey scores are publically available and incorporated into the dialysis payment system. Despite its importance, little is known about factors associated with better experience scores. We studied the association between patient-level characteristics and experience scores in a large real-world cohort of HD patients. METHODS: This is a cross-sectional analysis of ICH CAHPS administration in 2012. All in-center HD patients in Dialysis Clinic, Incorporated facilities nationally over 18 years old and receiving HD at their facility for at least 3 months were eligible. Predictors include patient demographic, clinical, and treatment-related characteristics. Outcomes include high global rating scores across three domains (Nephrologist, Dialysis Staff, Dialysis Center) and high composite scores across three domains (Nephrologists' Communication and Caring, Quality of Dialysis Center Care and Operations, and Providing Information to Patients). RESULTS: Among 3369 respondents, older age and telephone (vs. mail) administration of the survey were associated with higher global ratings, while shortened HD treatments were associated with lower global ratings. Lower education and telephone administration were associated with higher composite scores, while older age, and shortened HD treatments were associated with lower composite scores. CONCLUSIONS: Several patient characteristics and mode of survey administration are associated with higher experience scores. Future research should assess HD facility characteristics associated with higher scores and interventions that might improve experience accounting for these associations.

Evaluation of non-response to the In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey.

BACKGROUND: The In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) Survey is the first patient reported outcome measure included in the U.S. Medicare End Stage Renal Disease Quality Incentive Program. Administered twice yearly, it assesses in-center dialysis experience and survey responses are tied to dialysis facility payments. Low response rates, currently approximately 35%, raise concern for possible underrepresentation of patient groups. METHODS: Cross-sectional analysis of survey administration in 2012 to all in-center hemodialysis patients in Dialysis Clinic, Inc. (DCI) facilities nationally over 18 years old who received hemodialysis at their facility for at least 3 months. Patient-level covariates included demographic, clinical, laboratory, and functional characteristics. Random effects multivariable logistic regression was used to assess survey non-response. RESULTS: Among 11,055 eligible patients 6541 (59%) were non-responders. Of the remaining 4514 responders, 549 (14%) surveys were not usable due to presence of proxy help or incomplete responses. Non-responders were more likely to be men, non-white, younger, single, dual Medicare/Medicaid eligible, less educated, non-English speaking, and not active on the transplant list; non-responders had longer ESRD vintage, lower body mass index, lower serum albumin, worse functional status, and more hospitalizations, missed treatments, and shortened treatments. Similar associations were found using more parsimonious multivariable analyses and after imputing missing data. CONCLUSIONS: Non-responders to the ICH CAHPS significantly differed from responders, broadly spanning individuals with fewer socioeconomic advantages and greater illness burden, raising limitations in interpreting facility survey results. Future research should assess reasons for non-response to improve ICH CAHPS generalizability and utility.

Background frequency of Bacillus species at the Canberra Airport: A 12 month study.

Anthrax, caused by Bacillus anthracis, is a naturally occurring disease in Australia. Whilst mainly limited to livestock in grazing regions of Victoria and New South Wales, movement of people, stock and vehicles means B. anthracis could be present outside this region. Of particular interest is the "background" prevalence of B. anthracis at transport hubs including airports. The aim of this study was to determine the background frequency of B. anthracis and the commonly used hoax agent Bacillus thuringiensis at the Canberra Airport over a 12 month period. Samples were collected daily for seven days each month from August 2011-July 2012 and analyzed using species specific real-time polymerase chain reaction. Fourteen samples (of a total of 575) were positive for the B. anthracis PL3 genomic marker, 24 for the cya (pXO1) plasmid marker and five for the capB (pXO2) plasmid marker. Whilst five samples were positive for both PL3 and cya, no samples were positive for all three markers hence there is no evidence to suggest the presence of pathogenic B. anthracis strains. B. anthracis targets were detected primarily in February 2012 and B. thuringiensis peaked in October and November 2011 and again in April and May 2012. This study provides a rapid method to screen for, and differentiate, Bacillus species. Armed with this information investigators will be able to discriminate a "threat" from "background" frequencies should the need arise.

Satisfaction with Care of Patients on Hemodialysis.

BACKGROUND AND OBJECTIVES: Little is known about patients receiving dialysis who respond to satisfaction and experience of care surveys and those who do not respond, nor is much known about the corollaries of satisfaction. This study examined factors predicting response to Dialysis Clinic, Inc. (DCI)'s patient satisfaction survey and factors associated with higher satisfaction among responders. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENT: A total of 10,628 patients receiving in-center hemodialysis care at 201 DCI facilities between January 1, 2011, and December 31, 2011, aged ≥18 years, treated during the survey administration window, and at the facility for ≥3 months before survey administration. Primary outcome was response to at least one of the nine survey questions; secondary outcome was overall satisfaction with care. RESULTS: Response rate was 77.3%. In adjusted logistic regression (odds ratios with 95% confidence intervals), race other than black (white race, 1.23 [1.10 to 1.37]), missed treatments (1.16 [1.02 to 1.32]) or shortened treatments (≥5 treatments, 1.40 [1.22 to 1.60]), more hospital days (>3 days in the last 3 months, 1.89 [1.66 to 2.15]), and lower serum albumin (albumin level <3.5 g/dl, 1.4 [1.28 to 1.73]) all independently predicted nonresponse. In adjusted linear regression, the following were more satisfied with care: older patients (age ≥63 years, 1.84 [1.78 to 1.90]; age <63 years, 1.91 [1.86 to 1.97]; P<0.001), white patients (1.76 [1.71 to 1.81]) versus black patients (1.93 [1.88 to 1.99]) or those of other race (1.93 [1.83 to 2.03]) (P<0.001), patients with shorter duration of dialysis (≤2.5 years, 1.79 [1.73 to 1.84]; >2.5 years, 1.96 [1.91 to 2.02]; P<0.001), patients who had missed one or fewer treatments (1.83 [1.78 to 1.88]) versus those who had missed more than one treatment (1.92 [1.85 to 1.98]; P=0.002) and those who had shortened treatment (for one treatment or less, 1.84 [1.77 to 1.90]; for two to four treatments, 1.87 [1.81 to 1.93]; for five or more treatments, 1.92 [1.87 to 1.98]; P=0.004). CONCLUSIONS: Survey results represent healthier and more adherent patients on hemodialysis. Shorter survey administration windows were associated with higher response rates. Older, white patients with shorter dialysis vintage were more satisfied.

Randomized controlled trials 3: Measurement and analysis of patient-reported outcomes.

The study of patient-reported outcomes, now common in clinical research, had its origins in social and scientific developments during the latter twentieth century. Patient-reported outcomes comprise functional and health status, health-related quality of life, and quality of life. The terms overlap and are used inconsistently, and these reports of experience should be distinguished from expressions of preference regarding health states. Regulatory standards from the USA and European Union provide some guidance regarding reporting of patient-reported outcomes. The determination that measurement of patient-reported outcomes is important depends in part on the balance between subjective and objective outcomes of the health problem under study. Instrument selection depends to a large extent on practical considerations. A number of instruments can be identified that are frequently used in particular clinical situations. The domain coverage of commonly used generic short forms varies substantially. Individualized measurement of quality of life is possible, but resource intensive. Focus groups are useful, not only for scale development but also to confirm the appropriateness of existing instruments. Under classical test theory, validity and reliability are the critical characteristics of tests. Under item response theory, validity remains central, but the focus moves from the reliability of scales to the relative levels of traits in individuals and items' relative difficulty. Plans for clinical studies should include an explicit model of the relationship of patient-reported outcomes to other parameters, as well as definition of the magnitude of difference in patient-reported outcomes that will be considered important. It is particularly important to minimize missing patient-reported outcome data; to a limited extent, a variety of statistical techniques can mitigate the consequences of missing data.

Recovery and identification of bacterial DNA from illicit drugs.

Bacterial infections, including Bacillus anthracis (anthrax), are a common risk associated with illicit drug use, particularly among injecting drug users. There is, therefore, an urgent need to survey illicit drugs used for injection for the presence of bacteria and provide valuable information to health and forensic authorities. The objectives of this study were to develop a method for the extraction of bacterial DNA from illicit drugs and conduct a metagenomic survey of heroin and methamphetamine seized in the Australian Capital Territory during 2002-2011 for the presence of pathogens. Trends or patterns in drug contamination and their health implications for injecting drug users were also investigated. Methods based on the ChargeSwitch(®)gDNA mini kit (Invitrogen), QIAamp DNA extraction mini kit (QIAGEN) with and without bead-beating, and an organic phenol/chloroform extraction with ethanol precipitation were assessed for the recovery efficiency of both free and cellular bacterial DNA. Bacteria were identified using polymerase chain reaction and electrospray ionization-mass spectrometry (PCR/ESI-MS). An isopropanol pre-wash to remove traces of the drug and diluents, followed by a modified ChargeSwitch(®) method, was found to efficiently lyse cells and extract free and cellular DNA from Gram-positive and Gram-negative bacteria in heroin and methamphetamine which could then be identified by PCR/ESI-MS. Analysis of 12 heroin samples revealed the presence of DNA from species of Comamonas, Weissella, Bacillus, Streptococcus and Arthrobacter. No organisms were detected in the nine methamphetamine samples analysed. This study develops a method to extract and identify Gram-positive and Gram-negative bacteria from illicit drugs and demonstrates the presence of a range of bacterial pathogens in seized drug samples. These results will prove valuable for future work investigating trends or patterns in drug contamination and their health implications for injecting drug users as well as enabling forensic links between seizures to be examined.

Heterogeneity of fibrosis patterns in non-alcoholic fatty liver disease supports the presence of multiple fibrogenic pathways.

BACKGROUND: Adult non-alcoholic fatty liver disease (NAFLD) involves lobular necroinflammatory activity and fibrosis is typically centrilobular, whereas paediatric NAFLD has predominantly portal fibrosis. The reasons for these differences are unclear. We aimed to determine (a) how centrilobular and portal fibrosis in children relate to histological parameters; and (b) whether atypical fibrosis patterns exist in adults that are unexplained by current fibrogenesis models. METHODS: Histological features of paediatric (n = 38) and adult (n = 56) NAFLD were assessed using conventional scoring systems. Keratin-7 immunostaining was used to assess hepatic progenitor cell numbers and the ductular reaction. Centrilobular and portal components of fibrosis were independently scored and fibrosis patterns were classified according to accepted types. Post-treatment (rosiglitazone/gastric banding) biopsies were also examined in adults. RESULTS: Twenty-six children (68.4%) had portal-predominant fibrosis, although the typical "adult" pattern was seen in 11 (28.9%). Portal fibrosis was associated with a ductular reaction (P = 0.021) and hepatic progenitor cell expansion (P < 0.001), whereas centrilobular fibrosis was associated with lobular inflammation (P = 0.026) and ballooning (P = 0.001). Before intervention, six adults (10.7%) had atypical fibrosis including 3 (5.4%) with a previously unrecognized pattern of very fine, non-zonal sinusoidal fibrosis. Despite improvements in steatosis and inflammation, more patients developed this unusual pattern after intervention with most having had surgery (9 of 10 adults; P < 0.001). CONCLUSION: Differing associations with portal and centrilobular fibrosis in children and atypical fibrosis patterns in adults suggest that multiple fibrogenic pathways exist in NAFLD. This has implications for therapy and understanding pathogenesis.

Temporal trends in health-related quality of life among hemodialysis patients in the United States.

BACKGROUND AND OBJECTIVES: Health-related quality of life (HRQOL) is a measure of the well being of hemodialysis patients and an independent prognostic predictor. Our aim was to determine whether HRQOL among hemodialysis patients has changed over time. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We retrospectively analyzed data collected by Dialysis Clinic, Inc. from adult patients starting hemodialysis between January 1, 1997 and May 31, 2006. The primary outcome was HRQOL assessed by Short Form 36, 6 to 18 months after and closest to the 1-year anniversary of starting hemodialysis. Secular trends were analyzed by linear regression for continuous variables and logistic regression for categorical ones. Year of starting dialysis was the predictor. A five-point difference on a 0 to 100 scale was considered clinically significant. RESULTS: Short Form 36 scores were available for 11,079 patients. Role physical, general health, vitality, social functioning, and physical component summary scores were unchanged among patients over the study period. Statistically significant (P < 0.05) but clinically insignificant changes were observed in physical functioning (-0.2 points/yr), bodily pain (+0.2 points/yr), mental health (+0.15 points/yr), and mental component summary scores (+0.13 points/yr). Only role emotional showed clinically significant improvement. Trends were unchanged after adjusting for age, gender, race, diabetes, hemoglobin, phosphorous, Kt/V, and albumin. CONCLUSIONS: Most HRQOL domains showed either no statistically significant change or statistically but not clinically significant change over almost a decade. These results suggest that, despite important developments in hemodialysis care since 1997, little progress was made in improving HRQOL of hemodialysis patients.

Comparison of drug dosing recommendations based on measured GFR and kidney function estimating equations.

BACKGROUND: Kidney disease alters the pharmacokinetic disposition of many medications, requiring dosage adjustment to maintain therapeutic serum concentrations. The Cockcroft-Gault (CG) equation is used for pharmacokinetic studies and drug dosage adjustments, but the Modification of Diet in Renal Disease (MDRD) Study equation is more accurate and more often reported by clinical laboratories than the CG equation. STUDY DESIGN: Diagnostic test study. SETTINGS & PARTICIPANTS: Pooled data set for 5,504 participants from 6 research studies and 4 clinical populations with measured glomerular filtration rate (GFR). INDEX TEST: Estimated kidney function using the MDRD Study and CG equations incorporating actual (CG) or ideal body weight (CG(IBW)) and standardized serum creatinine concentrations. REFERENCE TEST: Measured GFR assessed by using iodine-125-iothalamate urinary clearance. OUTCOME: Concordance of assigned kidney function categories designated by the Food and Drug Administration (FDA) Guidance for Industry for pharmacokinetic studies and recommended dosages of 15 medications cleared by the kidneys. RESULTS: Concordance of kidney function estimates with measured GFR for FDA-assigned kidney function categories was 78% for the MDRD Study equation compared with 73% for the CG equation (P < 0.001) and 66% for the CG(IBW) equation (P < 0.001). Concordance between the MDRD Study equation and CG and CG(IBW) equations was 78% and 75%, respectively (P < 0.001). Concordance of kidney function estimates with measured GFR for recommended drug dosages was 88% for MDRD Study equation compared with 85% for the CG equation (P < 0.001) and 82% for the CG(IBW) equation (P < 0.001), with lower concordance when dosing recommendations for drugs included narrow GFR ranges. Concordance rates between the CG and CG(IBW) equations and MDRD Study equation were 89% and 88%, respectively (P < 0.05). LIMITATIONS: Results based on simulation rather than pharmacokinetic studies. Outcome was drug dosage recommendations, rather than observed drug efficacy and safety. CONCLUSIONS: The MDRD Study equation can also be used for pharmacokinetic studies and drug dosage adjustments. As more accurate GFR-estimating equations are developed, they should be used for these purposes.