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Biomedical subjects

K C Johnson

Publications and source records attributed to K C Johnson.

At least 19 recordsLinked to original sources
PubMed2000

Effects on subject response of information brochures and small cash incentives in a mail-based case-control study.

PURPOSE: To investigate the impact on subject response of an information brochure and cash incentives included with mailed questionnaires in case-control studies. METHODS: A randomized trial was carried out within a case-control study investigating cancer in the Province of Ontario. Brochures were included with half of the mailed questionnaires sent to 7487 cases and 2561 controls. Controls were also sent cash incentives of $2, $5, or no money. RESULTS: With the brochure, response changed from 75.0% to 75.8% in cases, and from 70.3% to 71.1% in controls. Adjusting for differences in age, residence, sex, and cancer site/status, the change was 0.2% [95% confidence interval (CI) = -1.7-2.1] in cases, and 0.6% (95% CI = -3.1-4.3) in controls. The $2 and $5 incentives increased overall response in controls from 61.9% to 72.8% and 77.2%, respectively, i.e., by 10.9% (95% CI = 6.1-15.6) and 15.1% (95% CI = 10.4-19.7), after adjustment. This effect was largely confined to urban areas (for $2 and $5, respectively: 5.5% and 14.2% in Toronto, 15.3% and 20.4% in other urban areas vs. 2.7% and 1.0% in rural areas; p = 0.02). Response time showed little or no improvement when the brochure was included, but was markedly reduced for both the $2 and $5 incentives. CONCLUSIONS: Cash incentives can improve subject response in epidemiologic studies, whereas information brochures do not appear to have an effect.

Adult↗
PubMed2000

Alcohol, tobacco and coffee consumption and the risk of pancreatic cancer: results from the Canadian Enhanced Surveillance System case-control project. Canadian Cancer Registries Epidemiology Research Group.

The relationship between alcohol, tobacco and coffee consumption and pancreatic cancer was investigated using population-based case-control data obtained from eight Canadian provinces. Our findings are based on analyses performed on 583 histologically confirmed pancreatic cancer cases and 4813 controls. Questionnaire data were obtained directly from 76% of the cases. Male subjects with 35 or more cigarette pack-years had an increased risk of developing pancreatic cancer relative to never smokers (OR= 1.46, 95% CI 1.00-2.14). Similarly, women reporting at least 23 cigarette pack-years of smoking had an odds ratio of 1.84 (95% CI 1.25-2.69). For the most part, consumption of total alcohol, wine, liquor and beer was not associated with pancreatic cancer. Coffee drinking was not related to pancreatic cancer. More work is needed to clarify the role of these and other potentially modifiable risk factors as a means to reduce the incidence of this disease for which treatment results remain disappointing.

Adult↗
PubMed2000

Glycemic control of older adults with type 2 diabetes: findings from the Third National Health and Nutrition Examination Survey, 1988-1994.

BACKGROUND: Although nearly half of all people who have diabetes are aged 65 or older, glycemic control of older adults with diabetes has not been well described. METHODS: We conducted a cross-sectional study of 1,482 participants with self-reported type 2 diabetes in the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III), a nationally representative sample of the US noninstitutionalized civilian population. Variables included in this analysis included age, sociodemographic factors, drug treatment, and level of glycemic control. RESULTS: The mean % (+/-SE) HbA1c was 7.78 +/- 0.21, 7.64 +/- 0.18, 7.71 +/- 0.14, and 7.27 +/- 0.14 in persons aged 20 to 54, 55 to 64, 65 to 74 and > or = 75 years, respectively. The mean mg/dL (+/-SE) fasting plasma glucose (FPG) was 175.9 +/- 7.6, 164.5 +/- 6.1, 183.3 +/- 5.3, and 158.5 +/- 5.5 in the four age groups and older, respectively. When controlling for race, gender, education, and duration of diabetes, age was not significantly associated with levels of HbA1c [P (trend) =0.17] or FPG [P (trend) =0.19]. Among NHANES III participants aged 65 or older, ADA guidelines for glycemic control (HbA1c < 7%) were achieved by 71%, 44%, and 27% of persons using no drug therapy, oral hypoglycemic agents, and insulin, respectively. CONCLUSIONS: Although many older adults with type 2 diabetes do not achieve targets for glucose control, there is no evidence to suggest that community-dwelling older adults with diabetes are treated less vigorously than younger persons with diabetes.

Age Factors↗
PubMed1999

Risk factors for prostate cancer: results from the Canadian National Enhanced Cancer Surveillance System. The Canadian Cancer Registries Epidemiology Research Group.

OBJECTIVES: To evaluate the relationship between prostate cancer and several potential lifestyle risk factors. METHODS: We analyzed data obtained from a population-based case-control study conducted in eight Canadian provinces. Risk estimates were generated by applying multivariate logistic regression methods to 1623 histologically confirmed prostate cancer cases and 1623 male controls aged 50-74. RESULTS: Cases were more likely to have a first-degree relative with a history of cancer, particularly prostate cancer (OR = 3.1, 95% CI = 1.8-5.4). Reduced risks of prostate cancer were observed among those of Indian descent (OR = 0.2, 95% CI = 0.1-0.5) or any Asian descent (OR = 0.3, 95% CI = 0.2-0.6) relative to those of western European descent. Total fat consumption, tomato and energy intake, were not associated with prostate cancer. The risk of prostate cancer was inversely related to the number of cigarettes smoked daily (p = 0.06) and cigarette pack-years (p < 0.01), while no association was observed between the total number of smoking years or the number of years since smoking cessation. Anthropometric measures and moderate and strenuous levels of leisure time physical activity were not strongly related to prostate cancer. In contrast, strenuous occupational activities at younger ages appeared protective. CONCLUSIONS: Our analyses are limited by the absence of data related to tumor severity and screening history. Further studies are needed to investigate the relationship between behavioral risk factors and prostate cancer screening practices.

Aged↗
PubMed1999

Does syndrome X exist in hypertensive elderly persons with impaired glycemic control?

BACKGROUND: This report focuses on the glycemic state in relation to insulin and lipid levels of a cohort of elderly hypertensive persons to estimate the prevalence of syndrome X. METHODS: A cross-sectional study was performed at the University of Tennessee, Memphis, and the General Clinical Research Center (GCRC) on 95 participants in the Trial of Nonpharmacologic Interventions in the Elderly (TONE) study who agreed to participate in an ancillary study. A standard oral glucose tolerance test (OGTT) with insulin and C-peptide levels and a fasting lipid profile were obtained. RESULTS: In this sample of healthy elderly participants with hypertension who were taking an antihypertensive medication, 43 (45.3%) had normal glucose tolerance (NGT), 41 (43.2%) had impaired glucose tolerance (IGT), and 11 (11.6%) had undiagnosed non-insulin-dependent diabetes mellitus (NIDDM). Fasting hyperinsulinemia occurred in only one participant, who was in the IGT group. Hypertriglyceridemia and low high density lipoprotein (HDL) occurred in four persons, none of whom had hyperinsulinemia. Persons in the NIDDM and IGT groups had decreased beta cell function compared to persons in the NGT group, but did not have increased peripheral insulin resistance as estimated from the OGTT data. CONCLUSIONS: Our data demonstrated that in this cohort of elderly hypertensive participants with a high prevalence of central obesity, impaired glycemic control was common, but was not associated with fasting hyperinsulinemia or peripheral insulin resistance. Furthermore, we conclude that syndrome X essentially did not occur in these participants and postulate that the primary etiology for their impaired glycemic control is beta cell dysfunction. Further research is needed to elucidate these relationships.

Aged↗
PubMed1999

Calcium losses resulting from an acute bout of moderate-intensity exercise.

The purpose of this study was to compare daily calcium (Ca) losses in sweat (S) and urine (U) on an exercise day (E) with losses on the preceding day (i.e., a rest day) during which no exercise (NE) was performed. Ten healthy male volunteers (23.9 +/- 3.2 years) performed a single bout of moderate exercise (running at 80% HRmax) for 45 min in a warm (32 degrees C, 58% relative humidity) environment on E. When E and NE were compared, neither Ca intake (1,232 +/- 714 and 1, 148 +/- 482 mg, respectively) nor urinary Ca excretion (206 +/- 128 and 189 +/- 130 mg, respectively) were different (p >.05). Sweat Ca losses during the exercise bout averaged 45 +/- 12 mg. The results indicate that, although a small amount of Ca is lost in sweat during 45 min of moderate-intensity exercise, measured (sweat and urine losses combined) Ca losses (251 +/- 128 and 189 +/- 130 mg) were not different (p >.05) between days (E and NE, respectively). These data suggest that moderate exercise for up to 45 min in a warm, humid environment does not markedly increase Ca intake requirements.

Adult↗
PubMed1998

Does withdrawal of antihypertensive medication increase the risk of cardiovascular events? Trial of Nonpharmacologic Interventions in the Elderly (TONE) Cooperative Research Group.

The Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure recommends that attempts to discontinue antihypertensive drug therapy be considered after blood pressure (BP) has been controlled for 1 year. However, discontinuation of drug therapy could unmask underlying conditions and precipitate clinical cardiovascular events. The Trial of Nonpharmacologic Interventions in the Elderly (TONE) was a clinical trial of the efficacy of weight loss and/or sodium reduction in controlling BP after withdrawal of drug therapy in patients with a BP< 145/85 mm Hg on 1 antihypertensive medication. Of 975 participants, 886 entered the drug withdrawal phase of the trial and 774 were successfully withdrawn from their medications. Thirty-three events (stroke, transient ischemic attack, myocardial infarction, arrhythmia, congestive heart failure, angina, other) occurred between randomization and the onset of drug withdrawal (median time 3.6 months), 57 events occurred either during or after drug withdrawal (14.0 months), and 36 events occurred after resumption of antihypertensive therapy (15.9 months). Event rates per 100 person-years were 5.5, 5.5, and 6.8 for the 3 time periods (p=0.84) in the nonoverweight group and 7.2, 5.2, and 5.6 (p=0.08) in the overweight group. The study shows that antihypertensive medication can be safely withdrawn in older persons without clinical evidence of cardiovascular disease who do not have diastolic pressure > or = 150/90 mm Hg at withdrawal, providing that good BP control can be maintained with nonpharmacologic therapy.

Aged↗
PubMed1998

Sodium reduction and weight loss in the treatment of hypertension in older persons: a randomized controlled trial of nonpharmacologic interventions in the elderly (TONE). TONE Collaborative Research Group.

CONTEXT: Nonpharmacologic interventions are frequently recommended for treatment of hypertension in the elderly, but there is a paucity of evidence from randomized controlled trials in support of this recommendation. OBJECTIVE: To determine whether weight loss or reduced sodium intake is effective in the treatment of older persons with hypertension. DESIGN: Randomized controlled trial. PARTICIPANTS: A total of 975 [corrected] men and women aged 60 to 80 years with systolic blood pressure lower than 145 mm Hg and diastolic blood pressure lower than 85 mm Hg while receiving treatment with a single antihypertensive medication. SETTING: Four academic health centers. INTERVENTION: The 585 obese participants were randomized to reduced sodium intake, weight loss, both, or usual care, and the 390 nonobese participants were randomized to reduced sodium intake or usual care. Withdrawal of antihypertensive medication was attempted after 3 months of intervention. MAIN OUTCOME MEASURE: Diagnosis of high blood pressure at 1 or more follow-up visits, or treatment with antihypertensive medication, or a cardiovascular event during follow-up (range, 15-36 months; median, 29 months). RESULTS: The combined outcome measure was less frequent among those assigned vs not assigned to reduced sodium intake (relative hazard ratio, 0.69; 95% confidence interval [CI], 0.59-0.81; P<.001) and, in obese participants, among those assigned vs not assigned to weight loss (relative hazard ratio, 0.70; 95% CI, 0.57-0.87; P<.001). Relative to usual care, hazard ratios among the obese participants were 0.60 (95% CI, 0.45-0.80; P<.001) for reduced sodium intake alone, 0.64 (95% CI, 0.49-0.85; P=.002) for weight loss alone, and 0.47 (95% CI, 0.35-0.64; P<.001) for reduced sodium intake and weight loss combined. The frequency of cardiovascular events during follow-up was similar in each of the 6 treatment groups. CONCLUSION: Reduced sodium intake and weight loss constitute a feasible, effective, and safe nonpharmacologic therapy of hypertension in older persons.

Aged↗
PubMed1998

Plasma renin activity is associated with bone mineral density in premenopausal women.

Bone mineral density (BMD), plasma renin activity (PRA) and dietary calcium and sodium were evaluated in 47 Caucasian premenopausal women. All subjects were free of any disorder or medications known to affect calcium or bone metabolism. Those subjects with low PRA (< 1.3 ng/ml) had 4.3% lower BMD at the distal radius (p = 0.03). Other skeletal sites appeared to have lower BMD in subjects with low PRA but these differences were not statistically significant. There was a tendency for the low PRA group to have a lower dietary intake of calcium (p = 0.06) as compared with the normal PRA group (> or = 1.3 and < 4.0 ng/ml). Positive correlations were found between calcium intake and PRA (r = 0.26, p = 0.09); and between calcium/sodium intake and distal radial BMD (r = 0.31, p = 0.04), mid-radial BMD (r = 0.30, p = 0.04), total hip BMD (r = 0.23, p = 0.12) and total body BMD (r = 0.27, p = 0.07). This study provides preliminary evidence that a sodium intake > 3400 mg/day, as evidenced by the suppression of PRA, may affect bone mass and the effect may be modified by the level of calcium intake. Additional research is needed to replicate our findings with a larger sample size.

Adolescent↗
PubMed1998

The prognostic significance of asymptomatic carotid bruits in the elderly.

OBJECTIVE: To determine the association between asymptomatic carotid bruits and the development of subsequent stroke in older adults with isolated systolic hypertension. DESIGN: Retrospective cohort study. SETTING: The Systolic Hypertension in the Elderly Program (SHEP), a 5-year randomized trial testing the efficacy of treating systolic hypertension in noninstitutionalized persons aged 60 years or older. From the original 4,736 SHEP participants, we identified a cohort of 4,442 persons who had no prior history of stroke, transient ischemic attack, or myocardial infarction at randomization. MEASUREMENTS AND MAIN RESULTS: The end point for this ancillary study was the development of a stroke. The average follow-up was 4.2 years. Carotid bruits were found in 284 (6.4%) of the participants at baseline. Strokes developed in 21 (7.4%) of those with carotid bruits and in 210 (5.0%) of those without carotid bruits. The unadjusted risk of stroke among persons with carotid bruits was 1.53 (95% confidence interval [CI] 0.98, 2.40). Adjusting for age, gender, race, blood pressure, smoking, lipid levels, self-reported aspirin use, and treatment group assignment, the relative risk of stroke among persons with asymptomatic carotid bruits was 1.29 (95% CI 0.80, 2.06). Among SHEP enrollees aged 60 to 69 years, there was a trend (p = .08) toward increased risk (relative risk [RR] 2.05; 95% CI 0.92, 4.68) of subsequent stroke in persons with, compared to those without, carotid bruits. However, among enrollees aged 70 years or over, there was no relation between carotid bruit and subsequent stroke (RR 0.98; 95% CI 0.55, 1.76). In no other subgroup of SHEP enrollees did the presence of carotid bruit independently predict stroke. CONCLUSIONS: Although we cannot rule out a small increased risk of stroke associated with bruits in asymptomatic SHEP enrollees aged 60 to 69 years, the utility of carotid bruits as a marker for increased risk of stroke among asymptomatic elderly with isolated systolic hypertension aged 70 years or older is limited.

Aged↗
PubMed1998

Risk factors for glioma in adults: a case-control study in northeast China.

A case-control study of risk factors for glioma in adults was carried out in Heilongjiang province in northeast China. Between September 1989 and May 1995, 218 histologically confirmed cases of glioma requiring surgery for tumor removal (139 astrocytoma glioma and 79 other glioma) and 436 controls with non-neoplastic and non-neurological disease were recruited and personally interviewed in the wards of six major hospitals. Controls were matched by sex, age, and area of residence. Occupational, lifestyle, and medical information was obtained through a standardized questionnaire. Use of liquor was associated with cancer risk. Compared with males who never drank liquor, males with total lifetime liquor consumption of less than 1000 liters had an adjusted odds ratio (OR) of 1.60 (95% CI: 0.89-2.88) and for more than 1000 liters, 2.73 (95% CI: 1.06-7.08). Statistically significant associations were also found for diseases related to the brain (OR: 5.75; 95% CI: 1.08-30.47) and trauma to the head requiring medical attention (OR: 4.09; 95% CI: 2.51-10.31). Increased consumption of vegetables and of fruit were each associated with decreased glioma risk. Compared with lowest quartile intake, adjusted risks associated with highest quartile intake were 0.51 (95% CI: 0.29-0.89) for total vegetables and 0.28 (95% CI: 0.16-0.51) for total fruit.

Adult↗
PubMed1997

A case-control study of diet and lung cancer in northeast China.

A case-control study involving interviews with 227 lung-cancer cases and 227 matched hospital controls was conducted in Heilongjiang Province in northeast China to examine the influence of dietary factors on the risk of developing lung cancer. Lung-cancer cases were all incident cases judged to be suitable candidates for tumor removal by surgery. Controls were selected among hospitalized patients with non-neoplastic and non-lung disease. The overall male lung-cancer risks associated with cigarette smoking were similar to those reported in other Chinese studies but quite low compared to risks in Western countries. However, the subjects in this study were relatively young (average age 53.2), had started to smoke on average at a relatively old age (21.3 years), and only smoked an average of 18.7 cigarettes per day. Lung-cancer risk was not strongly associated with any of the nutrients examined, when all cases were compared to all controls. However, the data were suggestive of differences in the relationship of diet to risk among smokers and non-smokers. Cautious interpretation is required because of the wide confidence intervals due to limited sample size. Among the smokers, only higher beta-carotene was associated with estimates suggesting a lowered risk. Among non-smokers, the evidence suggested that increased vegetable consumption might reduce risk, consumption of any fruit might reduce risk but beta-carotene was unrelated to risk. The differences observed in the relationship of diet to lung-cancer risk between Chinese smokers and non-smokers warrant further study.

Case-Control Studies↗
PubMed1997

Demographic bias in physician smoking cessation counseling.

To determine if smoking cessation counseling is affected by physician or patient demographics, patient exit interviews and chart audits were administered between January 1991, and February 1992, in an inner-city teaching clinic. Patients who received medical care on an ongoing basis in the clinic were eligible for the study. Patients with dementia or inability to verbally communicate in English were excluded. According to patient self-report, 26% (167) of the 642 patients who participated were never asked about smoking. Of the 168 current smokers, 23% (39) were never advised to quit. Male patients were more likely to report being asked about smoking on the day of the clinic visit (odds ratio = 2.37, 95% confidence interval [CI] = 1.62 to 3.46). Male smokers were more likely to report being advised to quit (odds ratio 2.39, 95% CI = 1.25 to 4.58), as were white smokers (odds ratio 3.66, 95% CI = 1.37 to 9.82). According to patient report (smokers and nonsmokers), white physicians were more apt to ask about smoking on the day of the clinic visit (odds ratio = 2.68, 95% CI = 1.31 to 5.48). Physician and patient demographic characteristics may significantly influence the rate of smoking cessation counseling. Additional studies are needed to confirm the presence of such biases.

Adolescent↗
PubMed1997

Prevalence of undiagnosed non-insulin-dependent diabetes mellitus and impaired glucose tolerance in a cohort of older persons with hypertension.

OBJECTIVE: To determine the prevalence of undiagnosed non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) in a cohort of older persons with hypertension. To examine the usefulness of screening for NIDDM in this study population. DESIGN: Cross-sectional study. SETTING: University of Tennessee, Memphis and the General Clinical Research Center (GCRC). PATIENTS: Ninety-five participants in the Trial of Nonpharmacologic Interventions in the Elderly (TONE) study who agreed to participate in an ancillary study. MEASUREMENTS: A standard oral glucose tolerance test (OGTT) with insulin and C-peptide levels was performed before the beginning of the TONE intervention. RESULTS: In this cohort, 43 participants (45.3%) had normal glucose tolerance (NGT), 41 (43.2%) had IGT, and 11 (11.6%) had undiagnosed NIDDM. The positive predictive value for NIDDM of a fasting glucose > or = 115 mg/dL in our participants was 57%. Hyperinsulinemia occurred in only one participant, a subject in the IGT group. CONCLUSIONS: Our data demonstrate that undiagnosed NIDDM is common in our cohort of older persons who are being treated for essential hypertension and that impaired glucose tolerance may be more common than in the general population of the same age. Further, our data show that the vast majority of this older, obese, hypertensive cohort did not have fasting hyperinsulinemia. We also infer that a fasting glucose alone has a low positive predictive value for screening of NIDDM in our older cohort. As the prevalence of NIDDM and impaired glucose tolerance in older hypertensive patients in the general population is unknown, we believe that further investigation is needed to characterize the relationship of hypertension, glycemic status, and hyperinsulinemia in the general population.

Aged↗
PubMed1996

Guidance in the setting of drug particle size specifications to minimize variability in absorption.

PURPOSE: To provide guidance in setting particle size specifications for poorly soluble drugs to minimize variability in absorption. METHODS: A previously reported computer method was used to simulate the percent of dose absorbed as a function of solubility, absorption rate constant, dose, and particle size. RESULTS: The simulated percent of dose absorbed was tabulated over a realistic range of solubilities, absorption rate constants, and doses using drug particle sizes that might be typically found in a dosage form. CONCLUSIONS: The greatest effect of particle size on absorption was simulated for low dose- low solubility drugs. In general, the sensitivity of absorption to particle size decreased with increasing dose or solubility. At a solubility of 1 mg/mL, particle size had practically no effect on the percent of dose absorbed over the range of doses simulated (1-250 mg).

Computer Simulation↗