Biomedical subjects

K L Linton

Publications and source records attributed to K L Linton.

At least 19 recordsLinked to original sources

PubMed1998

Trends in hypertension prevalence, treatment, and control: in a well-defined older population.

To assess medical attention focused on hypertension (HBP) in the elderly, this study examines trends in HBP prevalence, treatment, and control status in a defined population of persons > or = 65 years of age enrolled in a large HMO. Random samples of approximately 400 persons were drawn for the years 1967, 1974, 1981, and 1988. First recorded ambulatory pressures, available on over 90% of subjects in each period, were obtained from medical records. Prevalence of HBP (SBP > or = 160 and/or DBP > or = 95, and/or taking anti-HBP drugs) ranged between 44% to 53%. Proportion with HBP on treatment increased from 25% in 1967 to 60% in 1988 (P<.001); proportion on treatment and controlled (SBP < 160, DBP < 95) increased from 8% to 34% (P<.001). Mean population SBP declined from 155.2 in 1967 to 144.0 in 1988 (P<.001); mean DBP declined from 85.2 to 81.2 (P<.001). Proportion with isolated systolic hypertension (ISH) (SBP > or = 160, DBP < 90) remained unchanged at 12% to 14%. Use of diuretics and adrenergic antagonist agents declined while use of beta blockers and newer classes of anti-HBP drugs increased significantly among treated hypertensives in the 1980s. These findings parallel HBP trends in younger adults from National Health Survey data though we find evidence of a substantial gap in addressing the problem in the elderly, who constitute the population at greatest risk of cardiovascular complications of HBP.

Adrenergic beta-Antagonists↗

PubMed1998

Characteristics of patients with asthma within a large HMO: a comparison by age and gender.

Adequate information about characteristics of asthmatic patients in large health maintenance organizations (HMOs) is still lacking. As part of an ongoing longitudinal study, baseline data were collected on 914 individuals aged 3 to 55 yr with physician-diagnosed asthma within a large HMO, Kaiser Permanente, NW Region. There were no significant differences between men and women in post-bronchodilator FEV1 when expressed as percent (%) predicted yet women with asthma reported more daytime and nocturnal symptoms than men (p = 0.002), and worse quality of life in all but three of 14 subscales in two asthma quality of life instruments. Specifically, women in the 35-55 yr age group uniformly reported worse physical functioning on the SF-36 quality of life scale (71 +/- 23 versus 85 +/- 18; p = 0.001), social functioning (73 +/- 21 versus 77 +/- 20; p = 0.016), and bodily pain (63 +/- 27 versus 72 +/- 24; p < 0.001). Also these women reported use of more health care (p = 0.002) and more medications for asthma than men (p < 0.01). Our data suggest that men and women respond differently to their asthma, and observed gender differences in various measures of asthma such as hospital admissions, quality of life, and use of metered dose inhalers (MDIs), may be related to this difference in response to disease, rather than to real differences in the disease between men and women. Understanding gender related differences in response to a chronic disease such as asthma is important in tailoring an education and management plan to each individual patient.

Activities of Daily Living↗

PubMed1997

Specialty differences in the management of asthma. A cross-sectional assessment of allergists' patients and generalists' patients in a large HMO.

OBJECTIVE: To examine the differences in medical management and quality of life between patients with asthma who receive their primary asthma care from allergists and those who receive their care from generalists in a large health maintenance organization (HMO). METHODS: We conducted a cross-sectional study of patients with asthma in a large HMO (Kaiser Permanente, Northwest Region, Portland, Ore). Participants were 392 individuals aged 15 through 55 years with physician-diagnosed asthma, taking antiasthma medications, reporting current asthma symptoms, and receiving asthma care from an allergist or from a generalist. Primary outcomes include characteristics of asthma, health care utilization, and quality of life. RESULTS: Patients cared for by allergists tended to have more severe asthma than those cared for by generalists (P < .01). The allergists' patients tended to be older (38.6 +/- 9.6 years vs 35.7 +/- 12.6 years, P < .01), more atopic (91% vs 78%, P < .01), and more likely to report perennial (rather than seasonal) asthma (26% vs 36%, P < .04) than the generalists' patients. Patients receiving their primary asthma care from an allergist were considerably more likely than generalists' patients to report using inhaled anti-inflammatory agents (P < .01), oral steroids (P < .01), and regular (daily) breathing medications to control their asthma (P < .01). Allergists' patients were more likely to have asthma exacerbations treated in a clinic setting rather than an emergency department (P < .01). Furthermore, allergists' patients reported significantly improved quality of life as measured by several dimensions of the SF-36 scale (physical functioning, role emotional, bodily pain, and general health; P < .05). CONCLUSIONS: These findings suggest that specialist care of asthma is of benefit for patients with asthma in a large HMO. Specifically, the allergists' patients conformed more closely to national asthma management guidelines and reported better quality of life than did the generalists' patients.

Adolescent↗

PubMed1995

A comparison of methods for correlated ordinal measures with ophthalmic applications.

For many clinical trials and epidemiologic investigations in the field of ophthalmology, paired ordinal data are often collected through the detailed grading of retinal photographs. One method for analysis of these data is the extension of the generalized estimating equation (GEE) methodology to multinomial data with cumulative link functions. Prior to the development of this advanced technique, however, ophthalmologists developed a method of combining the ordinal responses of both eyes of a patient into a single person-level response on a new ordinal scale. A relationship between the regression coefficients of these two methods is derived as a function of the correlation between eyes. We investigate the applicability of this result and the relationship of the standard errors in simulation experiments and in an example from the Wisconsin Epidemiologic Study of Diabetic Retinopathy.

Diabetic Retinopathy↗

PubMed1995

Pregnancy among Hispanic teenagers: is good parental communication a deterrent?

Effective communication between Hispanic parents and teens about sexual issues may deter adolescent pregnancy, yet little is known about the prevalence or impact of such communication. The study examined this potential relationship in a cohort of urban Hispanic adolescents. A questionnaire was administered to a non-random sample of pregnant and non-pregnant Hispanic women aged 12-18 years attending inner city schools in Los Angeles to obtain demographic, sexual activity and communication information. Logistic regression analysis was used to evaluate the independent contribution of risk factors to teenage pregnancy. Good communication with one's mother was inversely related to pregnancy; the adjusted odds ratio of pregnancy if the mother told the daughter about sex was 0.3 (95% CI 0.2-0.6). Friends' love was also inversely related to pregnancy (odds ratio 0.7; 95% CI 0.6-0.8). In order of increasing strength, alcohol and drug use, favorable attitude toward premarital sex, receipt of welfare, older age at menarche, and older age were all significantly related to pregnancy. Pregnant Hispanic teenagers have poorer communication with their parents than do other Hispanic teens. Efforts to reduce the incidence of adolescent pregnancy among Hispanics may need to address not only family communication but also issues outside the home such as alcohol and recreational drugs.

Adolescent↗

PubMed1995

Hypertension and lens opacities from the Beaver Dam Eye Study.

PURPOSE: To examine the relationship between hypertension and lens opacities, and the use of antihypertensive agents. METHODS: A total of 4,926 adults, 43 to 84 years of age, living in Beaver Dam, Wisconsin, at the time of a private census, were invited to participate in a study that included a medical interview and an examination that included ocular photography. All study procedures and photographic grading were done according to standard protocols. RESULTS: According to analysis with the Liang-Zeger multiple logistic regression model, people with hypertension were more likely to have posterior subcapsular opacities than people without hypertension (odds ratio, 1.39; 95% confidence interval, 1.05, 1.84). Specific medications for hypertension did not meaningfully affect the risk. Hypertension was associated with increased risk in both those with and without diabetes. CONCLUSIONS: Hypertension is associated with increased risk of posterior subcapsular opacities. The pathophysiologic mechanisms that may explain the relationship are unknown. Incidence data will give a better indication of temporal relationship between hypertension, medications to lower blood pressure, and lens opacities.

Adult↗

PubMed1995

Macular pucker after successful surgery for proliferative vitreoretinopathy. Silicone Study Report 8.

BACKGROUND: The prevalence of postoperative macular pucker and the factors associated with its development after successful surgery for proliferative vitreoretinopathy (PVR) using silicone oil or gas tamponade are unknown. METHODS: The postoperative status of the macula was determined by reviewing the photographs of 336 eyes taken 6 months after randomization. Two hundred eleven eyes with attached maculas were identified and analyzed to determine the prevalence of macular pucker after silicone oil and gas tamponades in eyes without (group 1) and with (group 2) previous vitrectomy surgery. Data obtained at baseline, from the primary study surgery, and from subsequent examinations and repeat surgeries during a follow-up period of 6 months were analyzed for factors associated with postoperative macular pucker. RESULTS: The 6-month-point prevalence rate of postoperative macular pucker was 15% (32 of 211 eyes). Ten of the 32 eyes were new cases of macular pucker. The authors were unable to document a difference in the 6-month-point prevalence of postoperative macular pucker between group 1 and group 2 eyes (13% versus 18%) or between eyes randomized to gas versus silicone oil (19% versus 12%). Postoperative pucker was three times as likely to develop in aphakic/pseudophakic eyes compared with phakic eyes (P = 0.02). Focal contraction posteriorly causing starfolds, and intravitreal contraction involving the vitreous base or vitreous cavity, were significantly less prevalent in eyes with postoperative macular pucker (P < 0.05). Large (> or = 2 disc diameters) retinal breaks (P = 0.04) were associated significantly with postoperative macular pucker (P = 0.04). The authors were unable to document an association between postoperative macular pucker and the type of adhesive modality used or the extent of its application. Postoperative visual acuity was significantly better if the macula was not puckered (P < 0.01). CONCLUSIONS: The occurrence of macular pucker after successful surgery for retinal detachments complicated by severe PVR is not influenced by the choice of intraocular tamponade. Certain preoperative factors may be associated with postoperative macular pucker.

Cohort Studies↗

PubMed1995

Parent participation in an adolescent drug abuse prevention program.

This study reports the level of participation of parents in a parent-targeted school-based drug prevention program, the differences between students whose parents participate and those who don't, and the implications for involving parents in future drug prevention programs. Among 1761 eligible seventh grade families, 1263 students (72%) and 1142 parents (65%) completed surveys assessing the quality of parent-child relationships as well as tobacco and alcohol use. Ten percent of eligible families attended at least one of the evening sessions. Compared to students whose parents completed the survey, students whose parents did not complete a survey were more likely to report they used tobacco, had more friends who used substances, were monitored less by their parents, had more risk-taking behaviors, had lower grade-point averages, and their parents had higher rates of tobacco and alcohol use. Parents who attended evening sessions had the lowest rates of tobacco use and reported spending the most time with their children. Parent-targeted drug preventions programs may stigmatize attending parents and may be unlikely to attract the highest risk families.

Adolescent↗

PubMed1994

Time parameters for glaucoma procedures.

Changes in physician reimbursement and the practice environment have emphasized the importance of determining physician time for procedures and services. Forty-five percent of the members of the American Glaucoma Society responded to a mail survey of estimates of the length of time and number of visits for the preoperative, operative, and 90-day postoperative care for six common glaucoma procedures. Results suggest a significant underestimation of time for trabeculectomies exists in the original and new resource-based relative value scale work values. Further, 47% to 53% of surgeons hospitalize patients on at least the first postoperative day. There were no apparent time efficiencies between "high-" and "low-volume" respondents. Thus, careful attention should be paid to the accuracy of certain time estimates and the resulting work values in the resource-based relative value scale. Additional work in this and other areas may prove illuminating.

Glaucoma↗

PubMed1994

The potential role of ophthalmology as an entry point to the healthcare system.

PURPOSE: To evaluate whether patients who receive ophthalmic care have other physicians and whether ophthalmologists can serve as a significant entry point to the healthcare system. METHODS: Two hundred fourteen patients at a tertiary care eye institute were surveyed regarding their non-ophthalmologist physicians. Demographic, medical, and other data also were collected through the survey. RESULTS: Twenty-eight percent of patients did not have a physician healthcare provider other than their ophthalmologist at their initial visit. Fifteen percent had no other physician, whereas 13% had one as a consequence of subsequent referral by the ophthalmologist. Even among those patients who were 40 years of age and older, 31% initially only had an ophthalmologist as their sole physician provider. Being older, female, and having Medicare, a Health Maintenance Organization membership, or private indemnity insurance were associated with a higher likelihood of having non-ophthalmologist physicians. CONCLUSIONS: These results suggest that a significant number of patients seeking eye care from an ophthalmologist have no other physician. These findings stress the need for eye care providers to have thorough medical education and clinical training. In addition, eye care may serve as a useful entry point into the healthcare system for a significant number of patients in the United States.

Adolescent↗

PubMed1993

The Beaver Dam Eye Study: the relation of age-related maculopathy to smoking.

There are conflicting reports regarding the relation of cigarette smoking to age-related maculopathy, a major cause of blindness in the United States. In this report, the authors examined this association in people aged 43-86 years (n = 4,771) who participated in the Beaver Dam Eye Study, Beaver Dam, Wisconsin (1988-1990). Exposure data on cigarette smoking were derived from questions about present and past smoking, duration of smoking, and the number of cigarettes smoked per day. Age-related maculopathy status was determined by grading stereoscopic color fundus photographs using the Wisconsin Age-related Maculopathy Grading System. Smoking status, pack-years smoked, and current exposure to passive smoking were not associated with drusen characteristics (type, area, and confluence) or signs of early age-related maculopathy in any age-sex group studied, except for a higher frequency of increased retinal pigment in males who had ever smoked compared with those who had never smoked. The relative odds for exudative macular degeneration, one form of late age-related maculopathy, in females who were current smokers was 2.50 (95% confidence interval 1.01-6.20) compared with those who were ex-smokers or never smokers; for males, it was 3.29 (95% confidence interval 1.03-10.50). There was no significant relation between smoking status and pure geographic atrophy, another form of late age-related maculopathy. These results suggest that exudative macular degeneration is associated with cigarette smoking and that different forms of macular degeneration may have different etiologies.

Adult↗

PubMed1993

Postoperative intraocular pressure abnormalities in the Silicone Study. Silicone Study Report 4.

BACKGROUND: Chronically abnormal intraocular pressure (IOP) may follow surgery for proliferative vitreoretinopathy (PVR), using either long-acting gas or silicone oil tamponade. Its prevalence and clinical significance are unclear. METHODS: In the Silicone Study, 241 eyes with severe (> or = C-3) PVR were treated with vitrectomy, randomized to perfluoropropane gas (C3F8) or silicone oil, and followed for 6 months or longer. Chronic IOP abnormalities, based on findings at two consecutive or any three postoperative visits, were defined as (1) low IOP (hypotony), 5 mmHg or less, or (2) elevated IOP, more than 25 mmHg. RESULTS: Eleven (5%) eyes had chronically elevated IOP and 58 (24%) had chronic hypotony. Chronically elevated IOP was more prevalent in eyes randomized to silicone oil than in those randomized to C3F8 gas (8% versus 2%; P < 0.05). Chronic hypotony was (1) more prevalent in eyes randomized to C3F8 gas than in those randomized to silicone oil (31% versus 18%; P < 0.05); (2) more prevalent in eyes with anatomic failure (48% versus 16%; P < 0.01); and (3) correlated with poor postoperative vision (P < 0.0001), corneal opacity (P < 0.001), and retinal detachment (P < 0.001). Factors prognostic of chronic hyotony included preoperative hypotony (P < 0.01), diffuse contraction of the retina anterior to the equator (P < 0.01), rubeosis (P = 0.02), and large retinal breaks (P = 0.02). In a multivariate analysis, diffuse contraction of the retina anterior to the equator remained an independent factor prognostic of chronic hypotony (odds ratio = 4.2), regardless of whether the retina was attached postoperatively. CONCLUSION: Intraocular pressure abnormalities are a common postoperative complication in eyes with PVR, and may occur with either C3F8 gas or with silicone oil. The presence of diffuse contraction of the retina anterior to the equator should alert the vitrectomy surgeon that the eye is likely to be hypotonus postoperatively.

Chronic Disease↗

PubMed1993

Vitrectomy with silicone oil or perfluoropropane gas in eyes with severe proliferative vitreoretinopathy. Silicone Study Report 3.

Between 1985 and 1990, 340 eyes with rhegmatogenous retinal detachment (RRD) and severe (stage C3 or worse) proliferative vitreoretinopathy (PVR) were treated with vitrectomy and randomly selected to receive perfluoropropane gas or silicone oil; 183 eyes had undergone no prior vitrectomy (group 1), and 157 eyes had undergone prior vitrectomy with intraocular gas tamponade (group 2). No differences were found between eyes in the two groups in achieving visual acuity of 5/200 or better (44% vs. 39%), macular reattachment (78% vs. 77%), or complete retinal reattachment (67% for both groups). In group 1, 74 eyes achieved complete retinal reattachment after only one operation; 41 additional eyes achieved reattachment after a second surgical procedure. In group 2, these numbers were 74 and 26, respectively. Eyes treated successfully after more than one operation were less likely to regain a visual acuity of 5/200 or better than those successfully treated with one operation (P < 0.01). There was no difference in hypotony between groups, but keratopathy was more frequent in eyes in group 2 (P < 0.05). The results suggest that differences in outcomes between group 1 and group 2 eyes are not as great as previously believed.

Adult↗

PubMed1993

Diagnostic x-ray exposure and lens opacities: the Beaver Dam Eye Study.

The Beaver Dam Eye Study is a population-based study of common age-related eye diseases. During the standardized medical history, the 4926 subjects were asked whether they had ever had a chest x-ray, computerized axial tomography (CAT) scan of the head, other x-rays of the head, x-rays of the abdomen, or other diagnostic x-rays. The eye examination included photographs of the lenses of the eyes, which were subsequently graded according to protocol. Nuclear sclerosis and posterior subcapsular opacity were significantly associated with CAT scans. If these relationships are causal, it would highlight the importance of minimizing such exposure to the lens of the eye.

Adult↗

PubMed1992

Prevalence of age-related maculopathy. The Beaver Dam Eye Study.

PURPOSE: The relationships of retinal drusen, retinal pigmentary abnormalities, and macular degeneration to age and sex were studied in 4926 people between the ages of 43 and 86 years who participated in the Beaver Dam Eye Study. METHODS: The presence and severity of various characteristics of drusen and other lesions typical of age-related maculopathy were determined by grading stereoscopic color fundus photographs using the Wisconsin Age-Related Maculopathy Grading System. RESULTS: One or more drusen were present in the macular area of at least 1 eye in 95.5% of the population. People 75 years of age or older had significantly higher frequencies (P less than 0.01) of the following characteristics than people 43 to 54 years of age: larger sized drusen (greater than or equal to 125 microns, 24.0% versus 1.9%), soft indistinct drusen (23.0% versus 2.1%), retinal pigment abnormalities (26.6% versus 7.3%), exudative macular degeneration (5.2% versus 0.1%), and geographic atrophy (2.0% versus 0%). CONCLUSION: These data indicate signs of age-related maculopathy are common in people 75 years of age or older and may pose a substantial public health problem.

Adult↗

PubMed1992

Prevalence of age-related lens opacities in a population. The Beaver Dam Eye Study.

Age-related lens opacities are common and are a frequent cause of loss of vision. The Beaver Dam Eye Study was designed to estimate the prevalence and severity of lens opacities in a rural community in the United States. Adults between the ages of 43 and 84 years, identified by private census, were examined and participated in the study (n = 4926). Photographs were taken of the lenses and were graded in masked fashion according to a standardized protocol. For nuclear sclerosis, more severe levels occurred more commonly in older age groups and in women. Overall, 17.3% had nuclear sclerosis more severe than level 3 in a 5-step scale of severity. Cortical opacities increased with increasing age and were more common in women. They were found in 16.3% of the population. Posterior subcapsular opacities occur in 6.0% of the population. There was a significant trend of greater prevalence at older ages, but no sex effect. The frequency of early cataract increased in both sexes through the age group 65 to 74 years, but declined in those 75 years of age and older. The frequency of late cataract increased consistently with age. Women were more severely affected than men. This study confirms that lens opacities are common in adults in the United States. These data are important for providing for social and health care needs. It is important to determine causes of cataracts in order to develop preventive programs.

Adult↗

PubMed1992

The Beaver Dam Eye Study. Retinopathy in adults with newly discovered and previously diagnosed diabetes mellitus.

The prevalence of diabetic retinopathy was examined in people with newly discovered noninsulin-dependent diabetes mellitus (NIDDM) (n = 50) and in those with previously diagnosed diabetes (n = 395) in a population-based study of people between the ages of 43 and 86 years who lived in Beaver Dam, Wisconsin between 1988 and 1990. Retinopathy was determined from stereoscopic fundus photographs. The prevalence of any retinopathy was 10.2% in those with newly diagnosed NIDDM, none had proliferative retinopathy, and 2.0% had macular edema. These data suggest that asymptomatic people discovered to have NIDDM during epidemiologic studies may not need immediate ophthalmoscopic examination at the time of their diagnosis because they have a relatively low risk of danger of visual loss due to diabetic retinopathy at that time.

Adult↗

PubMed1992

Intraocular pressure in an American community. The Beaver Dam Eye Study.

The Beaver Dam Eye Study is a population-based study of age-related eye diseases in persons 43-86 yr of age. Applanation tonometry was done on all study subjects. Mean intraocular pressure (IOP) increased significantly with age. Mean IOP differed little between the sexes and was not significantly different after age adjustment (in right eyes of 2721 women, it was 15.5 mm Hg, and in right eyes of 2135 men, it was 15.3 mm Hg). There was an association of IOP with systolic and diastolic blood pressures, body mass index, hematocrit, serum glucose, glycohemoglobin, cholesterol level, pulse, nuclear sclerosis, season, and time of day of measurement. These data confirm that, in a general population, IOP is associated with important systemic and ocular characteristics. Those characteristics should be considered in further research on determinants of IOP.

Adult↗