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Biomedical subjects

Eric L Knight

Publications and source records attributed to Eric L Knight.

12 recordsLinked to original sources
PubMed2004

Lifetime nonnarcotic analgesic use and decline in renal function in women.

BACKGROUND: Analgesics are commonly used and may impair kidney function. However, limited prospective information is available on the long-term effects of aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen on renal function. METHODS: A total of 1697 women participating in the Nurses' Health Study provided information on a mailed questionnaire in 1999 about lifetime use of acetaminophen, aspirin, and NSAIDs and provided blood samples in 1989 and 2000. The main outcome was change in estimated glomerular filtration rate (GFR) in 11 years. Multivariate logistic regression was used to determine the odds of developing the outcome according to lifetime analgesic intake. RESULTS: The mean +/- SD estimated GFR decreased from 88 +/- 17 to 79 +/- 17 mL/min per 1.73 m(2). There were no substantial differences in the unadjusted or estimated GFR levels among the categories of lifetime intake for the 3 analgesic groups at baseline or after 11 years. Acetaminophen use was associated with an increased risk of a GFR decline of at least 30 mL/min per 1.73 m(2) (P trend =.01) and a GFR decline of 30% or greater (P trend<.001), but aspirin and NSAID use were not. Compared with women consuming less than 100 g of acetaminophen, multivariate-adjusted odds ratio (95% confidence intervals) for a decline in GFR of at least 30 mL/min per 1.73 m(2) for women consuming more than 3000 g was 2.04 (1.28-3.24). CONCLUSIONS: Higher lifetime use of aspirin and NSAIDs is not associated with renal function decline, but high acetaminophen use may increase the risk of loss of renal function. The absolute risk of renal function decline due to even high lifetime analgesic intake seems to be modest.

Acetaminophen↗
PubMed2004

The quality of pharmacologic care for vulnerable older patients.

BACKGROUND: Although pharmacotherapy is critical to the medical care of older patients, medications can have considerable toxicity in this age group. To date, research has focused on inappropriate prescribing and policy efforts have aimed at access, but no comprehensive measurement of the quality of pharmacologic management using explicit criteria has been performed. OBJECTIVE: To evaluate the broad range of pharmacologic care processes for vulnerable older patients. DESIGN: Observational cohort study. SETTING: 2 managed care organizations enrolling older persons. PATIENTS: Community-dwelling high-risk patients 65 years of age or older continuously enrolled in the managed care organizations from 1 July 1998 to 31 July 1999. MEASUREMENTS: Patients' receipt of care as specified in 43 quality indicators covering 4 domains of pharmacologic care: 1) prescribing indicated medications; 2) avoiding inappropriate medications; 3) education, continuity, and documentation; and 4) medication monitoring. RESULTS: Of 475 vulnerable older patients, 372 (78%) consented to participate and had medical records that could be abstracted. The percentage of appropriate pharmacologic management ranged from 10% for documentation of risks of nonsteroidal anti-inflammatory drugs to 100% for avoiding short-acting calcium-channel blockers in patients with heart failure and avoiding beta-blockers in patients with asthma. Pass rates for quality indicators in the "avoiding inappropriate medications" domain (97% [95% CI, 96% to 98%]) were significantly higher than pass rates for "prescribing indicated medications" (50% [CI, 45% to 55%]); "education, continuity, and documentation" (81% [CI, 79% to 84%]); and "medication monitoring" (64% [CI, 60% to 68%]). LIMITATIONS: Fewer than 10 patients were eligible for many of the quality indicators measured, and the generalizability of these findings in 2 managed care organizations to the general geriatric population is uncertain. CONCLUSIONS: Failures to prescribe indicated medications, monitor medications appropriately, document necessary information, educate patients, and maintain continuity are more common prescribing problems than use of inappropriate drugs in older patients.

Aged↗
PubMed2004

Dietary factors and the risk of incident kidney stones in younger women: Nurses' Health Study II.

BACKGROUND: In older women and men, greater intakes of dietary calcium, potassium, and total fluid reduce the risk of kidney stone formation, while supplemental calcium, sodium, animal protein, and sucrose may increase the risk. Recently, phytate has been suggested to play a role in stone formation. To our knowledge, no prospective information on the role of dietary factors and risk of kidney stone formation is available in younger women. METHODS: We prospectively examined, during an 8-year period, the association between dietary factors and the risk of incident symptomatic kidney stones among 96 245 female participants in the Nurses' Health Study II; the participants were aged 27 to 44 years and had no history of kidney stones. Self-administered food frequency questionnaires were used to assess diet in 1991 and 1995. The main outcome measure was an incident symptomatic kidney stone. Cox proportional hazards regression models were used to adjust simultaneously for various risk factors. RESULTS: We documented 1223 incident symptomatic kidney stones during 685 973 person-years of follow-up. After adjusting for relevant risk factors, a higher dietary calcium intake was associated with a reduced risk of kidney stones (P =.007 for trend). The multivariate relative risk among women in the highest quintile of intake of dietary calcium compared with women in the lowest quintile was 0.73 (95% confidence interval, 0.59-0.90). Supplemental calcium intake was not associated with risk of stone formation. Phytate intake was associated with a reduced risk of stone formation. Compared with women in the lowest quintile of phytate intake, the relative risk for those in the highest quintile was 0.63 (95% confidence interval, 0.51-0.78). Other dietary factors showed the following relative risks (95% confidence intervals) among women in the highest quintile of intake compared with those in the lowest quintile: animal protein, 0.84 (0.68-1.04); fluid, 0.68 (0.56-0.83); and sucrose, 1.31 (1.07-1.60). The intakes of sodium, potassium, and magnesium were not independently associated with risk after adjusting for other dietary factors. CONCLUSIONS: A higher intake of dietary calcium decreases the risk of kidney stone formation in younger women, but supplemental calcium is not associated with risk. This study also suggests that some dietary risk factors may differ by age and sex. Finally, dietary phytate may be a new, important, and safe addition to our options for stone prevention.

Adult↗
PubMed2004

Kidney dysfunction, inflammation, and coronary events: a prospective study.

Kidney dysfunction and high C-reactive protein (CRP) levels are independently associated with coronary events. However, it is unclear whether the risk of coronary events associated with decreased kidney function is at least partially mediated by inflammation and whether the association between inflammatory biomarkers and coronary events is influenced by level of kidney function. With the use of a prospective, nested, case-control study design, the association among kidney function, inflammatory biomarker levels, and coronary events was studied. A total of 244 women who were participants in the Nurses' Health Study and had no history of cardiovascular disease received a diagnosis of an incident coronary event (defined as nonfatal myocardial infarction or death as a result of coronary disease) during the follow-up period from 1990 to 1998 and were matched to 486 control subjects. Serum creatinine and inflammatory biomarker levels were measured in blood samples collected in 1989. Creatinine clearance (CrCl) was estimated using creatinine, age, weight, and height. In multivariate analyses, the odds ratio (OR) for a coronary event in women with an estimated CrCl <60 ml/min was 2.33 (95% confidence interval [CI], 1.01 to 5.38) compared with those with a CrCl > or =90 ml/min. When soluble tumor necrosis factor receptor (sTNFR) I and II levels were added into this model individually, the observed OR for women with CrCl <60 ml/min was attenuated. In analyses stratified by estimated CrCl, higher high-sensitivity CRP (hs-CRP), IL-6, and sTNFR I and II levels each were significantly associated with an increased odds of coronary events in women with an estimated CrCl < or =74 ml/min but not in women with an estimated CrCl > or =75 ml/min. The OR per 5-mg/L unit increase in hs-CRP was 1.68 (95% CI, 1.13 to 2.52) for women with an estimated CrCl < or =74 ml/min, compared with 1.23 (95% CI, 0.86 to 1.76) and 0.99 (95% CI, 0.76 to 1.29) for women with an estimated CrCl 75 to 89 and > or =90 ml/min, respectively (P = 0.004 for interaction). In conclusion, kidney dysfunction is associated with an increased odds of coronary events, and inflammation, as assessed by higher sTNFR I and II levels, may mediate some of this risk. Higher inflammatory biomarkers levels, specifically, hs-CRP, IL-6, and sTNFR I and II, were significantly associated with coronary events only in women with reduced kidney function. These findings warrant further investigation in other populations.

Adult↗
PubMed2004

Factors influencing serum cystatin C levels other than renal function and the impact on renal function measurement.

BACKGROUND: It is well known that serum creatinine may be used as a marker of renal function only if taking into account factors that influence creatinine production, such as age, gender, and weight. Serum cystatin C has been proposed as a potentially superior marker than serum creatinine, because serum cystatin C level is believed to be produced at a constant rate and not to be affected by such factors. However, there are limited data on factors that may influence serum cystatin C levels, and there are limited data comparing cystatin C-based estimates of renal function with creatinine-based estimates that adjust for such factors, especially in individuals with normal, or mildly reduced, renal function. METHODS: This was a cross-sectional study of 8058 inhabitants of the city of Groningen, The Netherlands, 28 to 75 years of age. Serum cystatin C and serum creatinine levels were measured, and creatinine clearance was determined from the average of two separate 24-hour urine collections. We performed multivariate analyses to identify factors independently associated with serum cystatin C levels after adjusting for creatinine clearance. Then, partial Spearman correlations were obtained after adjusting for factors that may influence serum cystatin C and creatinine levels. We also compared the goodness-of-fit (R(2)) of different multivariate linear regression models including serum cystatin C level and serum creatinine level for the outcome of creatinine clearance. RESULTS: Older age, male gender, greater weight, greater height, current cigarette smoking, and higher serum C-reactive protein (CRP) levels were independently associated with higher serum cystatin C levels after adjusting for creatinine clearance. After adjusting for age, weight, and gender, the partial Spearman correlations between creatinine and, respectively, serum cystatin C level and serum creatinine level were -0.29 (P < 0.001) and -0.42 (P < 0.001), respectively. The R(2) values for serum cystatin C level and serum creatinine level adjusted for age, weight, and gender were 0.38 and 0.42, respectively. The addition of cigarette smoking and serum CRP levels did not improve the R(2) value for the multivariate serum cystatin C-based model. CONCLUSION: Serum cystatin C appears to be influenced by factors other than renal function alone. In addition, we found no evidence that multivariate serum cystatin C-based estimates of renal function are superior to multivariate serum creatinine-based estimates.

Adult↗
PubMed2003

The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency.

BACKGROUND: In individuals with moderate to severe renal insufficiency, low protein intake may slow renal function decline. However, the long-term impact of protein intake on renal function in persons with normal renal function or mild renal insufficiency is unknown. OBJECTIVE: To determine whether protein intake influences the rate of renal function change in women over an 11-year period. DESIGN: Prospective cohort study. SETTING: Nurses' Health Study. PARTICIPANTS: 1624 women enrolled in the Nurses' Health Study who were 42 to 68 years of age in 1989 and gave blood samples in 1989 and 2000. Ninety-eight percent of women were white, and 1% were African American. MEASUREMENTS: Protein intake was measured in 1990 and 1994 by using a semi-quantitative food-frequency questionnaire. Creatinine concentration was used to estimate glomerular filtration rate (GFR) and creatinine clearance. RESULTS: In multivariate linear regression analyses, high protein intake was not significantly associated with change in estimated GFR in women with normal renal function (defined as an estimated GFR > or = 80 mL/min per 1.73 m2). Change in estimated GFR in this subgroup over the 11-year period was 0.25 mL/min per 1.73 m2 (95% CI, -0.78 to 1.28 mL/min per 1.73 m2) per 10-g increase in protein intake; the change in estimated GFR was 1.14 mL/min per 1.73 m2 (CI, -3.63 to 5.92 mL/min per 1.73 m2) after measurement-error adjustment for protein intake. In women with mild renal insufficiency (defined as an estimated GFR > 55 mL/min per 1.73 m2 but <80 mL/min per 1.73 m2), protein intake was significantly associated with a change in estimated GFR of -1.69 mL/min per 1.73 m2 (CI, -2.93 to -0.45 mL/min per 1.73 m2) per 10-g increase in protein intake. After measurement-error adjustment, the change in estimated GFR was -7.72 mL/min per 1.73 m2 (CI, -15.52 to 0.08 mL/min per 1.73 m2) per 10-g increase in protein intake, an association of borderline statistical significance. High intake of nondairy animal protein in women with mild renal insufficiency was associated with a significantly greater change in estimated GFR (-1.21 mL/min per 1.73 m2 [CI, -2.34 to -0.33 mL/min per 1.73 m2] per 10-g increase in nondairy animal protein intake). CONCLUSIONS: High protein intake was not associated with renal function decline in women with normal renal function. However, high total protein intake, particularly high intake of nondairy animal protein, may accelerate renal function decline in women with mild renal insufficiency.

Adult↗
PubMed2003

The association between mental health, physical function, and hemodialysis mortality.

BACKGROUND: Mortality rates for individuals on chronic hemodialysis remain very high; therefore, strategies are needed to identify individuals at greatest risk for mortality so preventive strategies can be implemented. One such approach is to stratify individuals by self-reported mental health and physical function. Examining these parameters at baseline, and over time, may help identify individuals at greater risk for mortality. METHODS: We enrolled 14,815 individuals with end-stage renal disease (ESRD) and followed these individuals for up to 2 years. The mean age was 61.0 +/- 15.4 years (range, 20 to 96 years) and 31% were African Americans. The SF-36 Health Survey was administered 1 to 3 months after hemodialysis initiation and 6 months later. We examined the associations between the initial SF-36 Health Survey mental component summary (MCS) and physical component summary (PCS) scores and mortality during the follow-up period, and examined the associations between 6-month decline in PCS and MCS scores and subsequent mortality. We also examined the interactions between age and MCS and PCS scores. The general population-based mean of each of these scores was 50 with a standard deviation of 10. The main outcome measurement was death. RESULTS: Self-reported baseline mental health (MCS score) and physical function (PCS score) were both independently associated with increased mortality, and 6-month decline in these parameters was also associated with increased mortality. The multivariate hazard ratios for 1-year mortality for MCS scores of less than 30, 30 to 39, and 40 to 49 were 1.48 (95% CI, 1.32 to 1.64), 1.23 (95% CI, 1.14 to 1.32) and 1.18 (95% CI, 1.10 to 1.26) compared with a MCS score of 50 or more. The hazard ratios for PCS scores of less than 20, 20 to 29, and 30 to 39 were 1.97 (95% CI, 1.64 to 2.36), 1.62 (95% CI, 1.36 to 1.92), and 1.32 (95% CI, 1.11 to 1.57) compared with a PCS score of 50 or more. Six-month decline in self-reported mental health (hazard ratio, 1.07; 95% CI, 1.02 to 1.12, per 10-point decline in MCS score) and physical function (hazard ratio, 1.25; 95% CI, 1.18 to 1.33, per 10-point decline in PCS score) were also both significantly associated with an additional increase in mortality beyond baseline risk. We also found a significant interaction between age and physical function (P = 0.02). Specifically, there was a graded response between the PCS score category and mortality in most age strata, but this relationship was not observed in the oldest age (85 years old or older). CONCLUSION: In individuals newly initiated on chronic hemodialysis, self-reported baseline mental health and physical function are important, independent predictors of mortality, and there is a graded relationship between these parameters and mortality risk. Following these parameters over time provides additional information on mortality risk. One must also consider age when interpreting the relationship between physical function and mortality.

Adult↗
PubMed2003

High-normal blood pressure and microalbuminuria.

BACKGROUND: High-normal blood pressure (BP) is associated with increased cardiovascular risk compared with optimal BP, but no study has specifically examined the association between high-normal BP and microalbuminuria, an established predictor of future cardiovascular events. METHODS: This was a cross-sectional study of normotensive (systolic BP [SBP] < 140 mm Hg, diastolic BP [DBP] < 90 mm Hg) individuals without diabetes with no hypertension history enrolled in the Third National Health and Nutrition Examination Survey. BP was categorized as high normal (SBP, 130 to 139 mm Hg or DBP, 85 to 89 mm Hg), normal (SBP, 120 to 129 mm Hg or DBP, 80 to 84 mm Hg), and optimal (SBP < 120 mm Hg and DBP < 80 mm Hg). We also separately examined SBP, DBP, mean arterial pressure (MAP), and pulse pressure. Microalbuminuria was defined using sex-specific cutoff values (urine albumin-creatinine ratio > or = 17 and < or = 250 microg/mg [> or =1.0 and < or =28 mg/mmol] for men and > or = 25 and < or = 355 microg/mg for women [> or =3 and < or =40 mg/mmol]). We used multivariate logistic regression to analyze the association between different BP measurements and microalbuminuria. RESULTS: Compared with optimal BP, high-normal BP was significantly associated with increased odds of microalbuminuria (odds ratio [OR], 2.13; 95% confidence interval [CI], 1.51 to 3.01). Similarly, MAP (OR, 1.41; 95% CI, 1.15 to 1.74 per 10-mm Hg increment), SBP (OR, 1.27; 95% CI, 1.09 to 1.48 per 10-mm Hg increment), and DBP (OR, 1.29; 95% CI, 1.06 to 1.57 per 10-mm Hg increment) were significantly associated with microalbuminuria. CONCLUSION: High-normal BP is significantly associated with microalbuminuria compared with optimal BP and may be a biomarker of the increased cardiovascular risk observed in this population.

Adult↗
PubMed2003

Moderate alcohol intake and renal function decline in women: a prospective study.

BACKGROUND: The impact of moderate alcohol consumption on renal function has important public health implications given the high prevalence of alcohol use. Experimentally, alcohol may adversely affect renal function, but clinical data are limited and no large, prospective studies have examined this issue. METHODS: In a prospective study of 1658 nurses enrolled in the Nurses' Health Study, we sought to determine if there was an association between moderate alcohol consumption and rate of decline in renal function. Daily alcohol intake was measured in 1990, 1994 and 1998 using a detailed questionnaire. Maximum daily alcohol intake was measured in 1988. Creatinine, measured from blood samples provided in 1989 and 2000, was used to estimate glomerular filtration rate (GFR) and creatinine clearance (CCr). RESULTS: Compared to individuals with no alcohol intake, the odds ratios (ORs) for developing a >or=25% estimated GFR decline were: 0.98 (95% CI: 0.72-1.32) for 0.1-4.9 g/day, 0.83 (95% CI: 0.56-1.21) for 5-14.9 g/day and 0.81 (95% CI: 0.50-1.31) for 15-59.9 g/day. For women with hypertension (n = 726), the ORs for a >or=25% estimated GFR decline were: 0.98 (95% CI: 0.53-1.21) for 0.1-4.9 g/day, 0.62 (95% CI: 0.34-1.12) for 5-14.9 g/day and 0.53 (95% CI: 0.25-1.12) for 15-59.9 g/day. CONCLUSIONS: Moderate alcohol consumption had no substantial adverse effect on renal function in women over an 11 year follow-up period.

Alcohol Drinking↗
PubMed2003

A comparison of prediction equations for estimating glomerular filtration rate in adults without kidney disease.

The ability of the Modification of Renal Disease (MDRD) equation to predict GFR when compared with multiple other prediction equations in healthy subjects without known kidney disease was analyzed. Between May 1995 and December 2001, a total of 117 healthy individuals underwent (125)I-iothalamate or (99m)Tc-diethylenetriamine-pentaacetic acid (DTPA) renal studies as part of a routine kidney donor evaluation at either Brigham and Women's Hospital or Boston Children's Hospital. On chart review, 100 individuals had sufficient data for analysis. The MDRD 1, MDRD 2 (simplified MDRD equation), Cockcroft-Gault (CG), Cockcroft-Gault corrected for GFR (CG-GFR), and other equations were tested. The median absolute difference in ml/min per 1.73 m(2) between calculated and measured GFR was 28.7 for MDRD 1, 18.5 for MDRD 2, 33.1 for CG, and 28.6 for CG-GFR in the (125)I-iothalamate group and was 31.1 for MDRD 1, 38.2 for MDRD 2, 22.0 for CG, and 31.1 for CG-GFR in the (99m)Tc-DTPA group. Bias was -0.5, -3.3, 25.6, and 5.0 for MDRD 1, MDRD 2, CG, and CG-GFR, respectively, in subjects who received (125)I-iothalamate and -33.2, -36.5, 6.0, and -15.0 for MDRD 1, MDRD 2, CG, and CG-GFR, respectively, in those who received (99m)Tc-DTPA studies. Precision testing, as measured by linear regression, yielded R(2) values of 0.04 for CG, 0.05 for CG-GFR, 0.15 for MDRD 1, and 0.14 for MDRD in those who underwent (125)I-iothalamate studies and 0.18 for CG, 0.21 for CG-GFR, 0.40 for MDRD 1, and 0.38 for MDRD 2 for those who underwent (99m)Tc-DTPA studies. The MDRD equations were more accurate within 30 and 50% of the measured GFR compared with the CG and CG-GFR equations. When compared with the CG equation, the MDRD equations are more precise and more accurate for predicting GFR in healthy adults. The MDRD equations, however, consistently underestimate GFR, whereas the CG equations consistently overestimate measured GFR in people with normal renal function. In potential kidney donors, prediction equations may not be sufficient for estimating GFR; radioisotope studies may be needed for a better assessment of GFR. Further studies are needed to derive and assess GFR prediction equations in people with normal or mildly impaired renal function.

Adolescent↗
PubMed2002

Which patients with unstable angina or non-Q-wave myocardial infarction should have immediate cardiac catheterization? A clinical decision rule for predicting who will fail medical therapy.

Unstable angina and non-Q-wave myocardial infarction (MI) are common and costly clinical events, but there is considerable uncertainty about optimal clinical management of these syndromes. We developed a prediction rule to help clinicians determine which patients with unstable angina or non-Q-wave MI are likely to "fail" medical therapy and ultimately require cardiac catheterization within 6 weeks of presentation. Subjects were 733 patients presenting with unstable angina or non-Q-wave MI enrolled in the TIMI IIIB trial and randomized to initial medical management. We developed a prediction rule based on logistic regression analysis of baseline data from history, physical examination, electrocardiogram, and blood studies. The outcome of interest was "failure" of medical therapy, defined as need for coronary catheterization within 42 days. Significant predictors of "failing" medical therapy included ST segment depression >or= .1 mV (odds ratio, OR, = 2.7, 95% confidence interval, CI, 1.8-4.1), accelerated angina in the prior 2 months (OR = 1.8, 95% CI 1.2-2.6), nitrate use in the prior week (OR = 1.6, 95% CI 1.1-2.2), exertional angina in the prior 2 months (OR = 1.6, 95% CI 1.1-2.2), and cardiac troponin I (cTnI) >or= 0.4 ng/mL (OR = 1.4, 95% CI 1.1-1.9). We used these variables to build a risk score by assigning point values based on these ORs. The risk score had a moderate ability to predict which patients would subsequently fail medical therapy and undergo cardiac catheterization (c = 0.682). Out of a total risk score of 13, failure of medical therapy occurred in 86% of patients who had a risk score >or= 8 (n = 111), 78% of patients who had a risk score >or= 6 (n = 240), and 72% of patients who had a risk score >or= 4 (n = 438). At scores of < 2 (n = 88), 40% of patients failed medical therapy. Although the management of unstable angina is in constant evolution, clinicians will always be faced with determining which patients should be managed most invasively. The simple prediction rule we present can be applied to patients with unstable angina or non-Q-wave MI at the time of presentation to predict which patients have a high probability of failing medical therapy. Such a rule may be useful for identifying patients who should be considered for early cardiac catheterization.

Adult↗