The relationship of bone mass and fracture history to fluoride and calcium intake: a study of three communities.

Stimulated by the suggestion that water fluoride greater than 1 mg/L may protect against osteoporosis, we studied bone mass of women in three rural communities with differing mineral content of the water supply. Mean fluoride and calcium of community drinking waters were 4 mg/L and 16 mg/L, respectively, high fluoride community; 1 mg/L and 375 mg/L, respectively, high calcium community; and 1 mg/L and 65 mg/L, respectively, low calcium community. Bone mass was measured by single photon absorptiometry, and women were interviewed about fracture history, dietary intake, and other important covariates. We observed no protective effect with higher fluoride intake. Bone mass was lower in older women from the high fluoride community though not statistically so; these women reported significantly more fractures. There was no observed community difference in young women's bone mass or fracture history. Young women in the high fluoride community consuming calcium and vitamin D in excess of 800 mg/day and 400 IU/day, respectively, had significantly better bone mass (p less than 0.05) than their peers.

Correlates of mid-radius bone density among postmenopausal women: a community study.

We surveyed mid-radius bone density in a geographically-defined population of 324 women, 55-80 years old from two small, demographically-similar communities whose water supply provided 60 mg/l and 375 mg/l of elemental calcium. Mean community calcium intakes were 964 mg/day and 1329 mg/day respectively. Bone density, measured by photon densitometry, was correlated with physical measurements, medical history, and reported nutritional intake. Mid-radius bone density decreased with age while the following additional factors were independently and positively associated with bone density: humeral muscle area (p = 0.0001), extended estrogen use (p = 0.0004), thiazide use (p = 0.0029), and vitamin D intake (p = 0.0104). Estimated total calcium intake alone did not significantly correlate with bone density; however, mean bone density was significantly greater in persons whose calcium intake was greater than 800 mg/day, consumed concurrently with vitamin D in amounts greater than 400 IU (p = 0.0342), the Recommended Daily Allowance of these two nutrients.

The association of intakes of vitamin D and calcium with blood pressure among women.

Blood pressure and its relationship to nutritional factors, particularly intakes of calcium and vitamin D, were evaluated among 86 women, aged 20-35 yr, and 222 women, aged 55-80 yr, who were not using diuretics. Observations were based on a study of bone density among women in two communities which included blood pressure determinations, a food frequency estimate of calcium intake, a 24-h dietary recall and an extensive supplement use history. There was no significant relationship between estimated current dietary calcium consumption and blood pressure in either age group. However, in younger women, there was a significant inverse relationship between estimated dietary intake of vitamin D and systolic blood pressure which remained significant (p = 0.0016) after adjusting for age, Quetelet index, alcohol consumption and calcium intake. Older women whose consumption of both vitamin D and calcium was less than the Recommended Dietary Allowance, 400 IU/day and 800 mg/day respectively, had a significantly higher systolic blood pressure (p = 0.0371) than their counterparts whose estimated intake met the RDA for at least one of the two nutrients. Vitamin D may be related to blood pressure through its regulation of calcium absorption from the gut or its interaction with parathyroid hormone in maintaining plasma calcium homeostasis.

Parameters related to 25-OH-D levels in a population-based study of women.

We surveyed calcidiol levels (25-OH-D) in a geographically-defined population of 373 women, ages 20-80 yr to test for an association between occult osteomalacia and excess bone loss. Bone mass was measured by photon densitometry and an estimate of vitamin D was determined by measuring dietary and supplemental intake as well as sunlight exposure equivalent. The relationship of smoking practices, alcohol use, exogenous estrogen use, and medications to calcidiol level was assessed. Calcidiol levels were not associated with bone mass levels observed at two different forearm sites. Low levels of calcidiol, indicative of generalized vitamin D deficiency, were not observed in this population though mean estimates of vitamin D intakes from food 119 +/- 148 IU) or food and supplements (319 +/- 463 IU) were less than the Recommended Dietary Allowance (400 IU). Calcidiol was significantly associated with estimates of vitamin D intake from food (r = 0.11), supplement use (r = 0.21), and sunlight equivalent exposure (r = 0.26). Calcidiol levels were negatively related to age (p = 0.0020) and positively related to exogenous estrogen use and premenopausal state independent of age.

Relationship between 1,25-dihydroxyvitamin D and blood pressure in a geographically defined population.

In a cross-sectional, population-based study we measured casual, seated blood pressure with a random-zero sphygmomanometer and 1,25-dihydroxyvitamin D (1,25-[OH]2D) with a protein-binding assay in 373 women aged 20-80 y. 1,25-(OH)2D, an active metabolite that regulates serum calcium, was associated significantly and positively with systolic blood pressure (p = 0.020) and diastolic blood pressure (p = 0.003) after adjustment for age, Quetelet's index (a measure of obesity), and current thiazide use. A model including age, Quetelet's index, current thiazide use, and 1,25-(OH)2D explained 37% of the variability in systolic blood pressure observations, of which 7% of variability was explained by 1,25-(OH)2D. In this geographically defined population of women, the variability of blood-pressure measurements attributable to 1,25-(OH)2D was of the same order of magnitude as that attributable to Quetelet's index.

Divalent ion handling in human kidney donors with increased blood pressure after uninephrectomy.

In a prospective study of 21 normal human kidney donors, increases in blood pressure were found in seven of 12 males and in three of nine females within the first year after uninephrectomy. Donors with blood pressure increases were characterized by greater weight and body mass indexes. In addition, urinary phosphate excretion was positively correlated (r = 0.73, p less than 0.001) and tubular reabsorption of phosphate negatively correlated (r = -0.61, p less than 0.01) with blood pressure at the follow-up periods in which increases were observed. All donors experienced an increase in parathyroid hormone levels and urinary cyclic AMP excretion. These changes were accompanied by decreases in urinary calcium and serum phosphate values. Thus, the increase in blood pressure took place in a milieu similar to that of "normocalcemic" hyperparathyroidism. The correlation of phosphate excretion and blood pressure in normal donors suggests an important role for phosphate metabolism in the genesis of hypertension associated with loss of renal mass.

Statistical analysis of K 2 x 2 tables: a comparative study of estimators/test statistics for association and homogeneity.

In order to control for confounding variables, epidemiologists often obtain data in the form of a 2 x 2 table. One variable is usually the disease status, while the other variable represents a dichotomous exposure variable that is suspected of being a risk factor. If a confounding variable is present, the data are often stratified into several 2 x 2 tables. The objectives of the analysis are to test for the association between the suspected risk factor and the disease and to estimate the strength of this relationship. Before estimating a common odds ratio, it is important to check whether the odds ratios are homogeneous. This paper presents the results of a Monte Carlo study that was performed to determine the size and power of a number of tests of association and homogeneity when the data are sparse. We also evaluated the performance of three estimators of the common odds ratio. For the Monte Carlo studies, equal numbers of cases and controls were used in a wide variety of sparse data situations. On the basis of these studies, we recommend the Breslow-Day test for nonsparse data, and the T4 and T5 statistics for sparse data to test for homogeneity. The Mantel-Haenszel test of association is recommended for sparse and nonsparse data sets. With sparse data, none of the odds ratio estimators are entirely satisfactory.

Urinary incontinence in rural older women: prevalence, incidence and remission.

OBJECTIVES: To determine the prevalence, incidence, and remission rates of urinary incontinence in a large group of older women over a 6-year time span and to assess factors associated with incontinence incidence and remission. DESIGN: Longitudinal cohort study. SETTING: Two rural counties in Iowa. PARTICIPANTS: 2025 women aged 65 years or older residing in rural Iowa, enrolled in the Iowa 65+ Rural Health Study of EPESE (Establishment of Populations for Epidemiologic Studies of the Elderly) were interviewed in person annually for 6 years; specific responses to queries about urinary incontinence were given at baseline, 3-, and 6-year intervals. MEASUREMENTS: Conditional multivariate logistic regression analysis was done to assess the relationship between incontinence symptoms and various factors previously found to be related to incontinence. RESULTS: The baseline prevalence of urge incontinence was 36.3%, and of stress incontinence it was 40.3%. For urge incontinence, the 3-year incidence and remission rates between the third and sixth years were 28.5% and 22.1%, respectively. For stress incontinence, the 3-year incidence and remission rates between years 3 and 6 were 28.6% and 25.1%, respectively. Seventy-six percent and 84% of women who reported no urge or stress incontinence, respectively, at the baseline interview were continent at both follow-up interviews. The only significant factors related to changes in incontinence status were age, which was associated with an increased incidence of urge incontinence (OR 1.11, P = .017, 95% CI 1.019-1.203), and improvement in activities of daily living, which was associated with a increased remission of urge incontinence (OR 0.50, P = .015, 95% CI 0.28-0.9) CONCLUSION: In some older women, urinary incontinence is a dynamic state, with women moving back and forth along a continuum between continence and incontinence. These results are tempered by limitations of the study, which include its questionnaire design and lack of ability to detect potential treatment effect.

An introduction to time-trend analysis.

Healthcare professionals often are presented with data that appear to indicate an upward or downward trend over time. For example, admissions of acquired immunodeficiency syndrome (AIDS) patients appear to be increasing, cesarean section rates appear to be decreasing, or nosocomial pneumonia rates appear to be increasing. Critical decisions sometimes are based on such trends, which often are presented without a statistical analysis. Those responsible for decision making may be left wondering whether these apparent trends represent only chance variation. Graphs showing trends over time generally present one of three kinds of outcome data: counts (eg, three AIDS admissions), proportions (eg, 10 cesarean sections per 100 total deliveries), or person-time data (eg, 13 cases of nosocomial pneumonia per 10,000 patient days). Using familiar examples and a minimum of technical language, we illustrate the analysis of time trends.

Prevalence and characteristics of multiple analgesic drug use in an elderly study group.

With few exceptions, use of multiple analgesic drugs achieves dubious increases in analgesia while placing elders at increased risk of the many potential adverse effects of analgesic drugs. The potential for duplication of analgesic therapy among the elderly is great due to prevalent painful chronic conditions and the variety of prescription and nonprescription analgesic remedies available. The prevalence of multiple analgesic product use and patterns of concurrent use of different analgesic categories was investigated in a geographically defined population of persons 65 years of age and older. The demographic characteristics of users of multiple analgesic drug products were examined, as were their smoking status, alcohol use, lifetime history rates of major illnesses, physical functioning, pain experiences, memory performance, and depressive symptoms. A substantial proportion of analgesic users reported taking multiple products in the preceding 2 weeks (14.4% of female and 10.5% of male analgesic users). Men who reported pain in the preceding year were more likely to use multiple analgesic products. Women who experienced pain or limited physical functioning, or who had higher depressive symptom scores or a life-time history of ulcers were most likely to use multiple analgesic products. Thus, although some users of multiple analgesic products reported significant pain, several other factors were shown to be related to the phenomenon of multiple use.

Medication use characteristics in the elderly: the Iowa 65+ Rural Health Study.

Medication use was studied in a rural, elderly population. Household interviews were conducted of 3,467 individuals aged 65 years or older. A total of 9,955 prescription or nonprescription drugs were reported by the respondents. The overall mean number of drugs per respondent was 2.87, while 12% of all respondents were not taking any drugs. Mean prescription and overall drug use increased significantly with increasing age (P less than .001), while mean nonprescription drug use was relatively constant across age groups. Significantly more women were prescription and nonprescription drug users. Directions for scheduled daily dosing accounted for 75% of all directions. The majority of prescription and nonprescription drugs had been taken on the previous day. General practitioners accounted for more prescription drugs (39.7%) than any other medical specialty. The most frequently stated purpose was cardiovascular for prescription drugs and musculoskeletal for nonprescription drugs. The three most frequent prescription drug therapeutic categories were cardiovascular (54.7%), central nervous system (CNS) agents (11.4%), and analgesics (9.4%). For nonprescription drugs, the three most frequent therapeutic categories were analgesics (39.6%), vitamins and minerals (32.9%), and laxatives (14.1%). Implications of these findings are discussed.

Prevalence and functional correlates of low back pain in the elderly: the Iowa 65+ Rural Health Study.

As part of an interview survey of a defined population of 3,097 rural persons 65 years and older (the Iowa 65 + Rural Health Study), the prevalence and functional correlates of specifically defined low back pain were studied. Low back pain was reported by 23.6 per cent of the women and 18.4 per cent of the men in the year prior to the survey, with prevalence rates declining with age. Forty per cent of those with low back pain noted its presence at the time of the interview. Over half had used analgesics. Use of medical and chiropractic services for this symptom was nearly 75 per cent; 25 per cent had at least one hospitalization directly related to low back pain and over 5 per cent had low back surgery. Limitation of walking, sitting, bending over, and performing household chores was reported by 15 to 40 per cent, and 21 per cent attributed sleep disturbance to the low back pain. Nearly 75 per cent of subjects with low back pain reported first onset of the problem prior to age 65, which has important implications for pathogenesis and prevention. The functional and clinical burdens of low back pain in this population of rural elderly were substantial and require further evaluation of risk factors and impact on health status.

Physical activity, physical function, and the risk of breast cancer in a prospective study among elderly women.

BACKGROUND: Accumulating evidence suggests that physical activity may protect against the development of breast cancer, but less is known about the role of modest physical activity during the postmenopausal years and in the context of physical function. METHODS: We evaluated this association in the Iowa 65+ Rural Health Study, a population-based, prospective cohort study of elderly adults. The cohort was linked to a population-based cancer registry for the years 1973-93, and the at-risk cohort consisted of 1806 women ages 65 to 102 years with an in-person baseline interview in 1982 and with no documented cancer between 1973 and the baseline interview. Through 1993 (16,857 person-years of follow-up) there were 46 incident cases of breast cancer. RESULTS: Greater level of physical activity in women with no physical disabilities was inversely associated with breast cancer risk (p for trend = .01). Compared to inactive women with no physical disability, women reporting moderate (age-adjusted relative risk [RR] = 0.5, 95% confidence interval [CI] 0.3-1.1) or high (age-adjusted RR = 0.2, 95% CI .05-0.9) activity levels were at decreased risk of breast cancer. Women with any disability were also at decreased risk of breast cancer compared to inactive women with no disability (age-adjusted RR = 0.4; 95% CI 0.2-0.9). Adjustment for education, body mass index, age at menarche, age at menopause, previous use of hormone replacement therapy, pregnancy history, systolic blood pressure, smoking, and alcohol use did not alter these associations. In addition, these associations were similar after exclusion of cases occurring during the first two years of follow-up, after adjusting for the number of doctor visits, and after stratifying by stage at diagnosis. CONCLUSIONS: These data suggest that postmenopausal activity level, after accounting for physical disability, is inversely associated with breast cancer risk.

Correct placement of epidural steroid injections: fluoroscopic guidance and contrast administration.

We prospectively evaluated 316 caudal-approach epidural steroid injections given by staff radiologists and residents in our department over a 1-year period. Needle placement was checked with fluoroscopy and corrected if necessary. When the needle tip was within the sacral canal, nonionic contrast material was injected. If epidural contrast was not observed, the needle tip was repositioned. Of 111 procedures performed by physicians who had given fewer than 10 epidural steroid injections, 53 (47.7%) resulted in correct nonfluoroscopically directed placement of the needle. For physicians who had performed between 10 and 50 such procedures, 62 (53.4%) of 116 had correct nonfluoroscopically directed placement. For staff physicians, 55 (61.7%) of 89 placements were correct. Even when the sacral hiatus was easily palpated and a staff physician was confident that he or she was within the epidural space, fluoroscopy revealed incorrect placement 14.2% of the time (seven of 49 procedures). In addition, when the needle was positioned within the sacral canal and no blood was evident on Valsalva maneuver or aspiration, the injection was venous in 29 of 316 procedures (9.2%). The presence of blood on the needle stylus was not a reliable indicator of venous placement of the needle. Our findings indicate that fluoroscopy is essential for correct placement of epidural steroid injection. Contrast administration is necessary to avoid venous injection of steroids.

Memory complaint and memory performance in the depressed elderly.

Depressed and nondepressed elderly subjects recruited in the context of a large epidemiological study of health were compared on measures of self-reported memory disturbance and an objective index of memory performance (free recall). Three groups were studied including (a) subjects meeting Research Diagnostic Criteria (RDC) for major depression, (b) subjects with high levels of self-reported depressive symptoms who did not meet RDC for major depression, and (c) subjects with low levels of self-reported depressive symptoms. Subjects with high depression symptom levels reported significantly higher levels of memory complaint than did subjects with low symptom levels. However, there were no differences in self-reported memory disturbance as a function of depression diagnosis. Further, there were no significant differences between groups on the free-recall measure, either as a function of symptom level or diagnosis. It is argued that symptom severity rather than diagnosis of depression is important in determining impairment in depressed elderly people.

Voice problems among teachers: differences by gender and teaching characteristics.

This study describes the effects of teaching activities on voice problems in male (n = 274) and female teachers (n = 280). Over 38% of the teachers studied complained that teaching had an adverse impact on their voice and 39% of those had cut back teaching activities as a result. Compared to males, female teachers more frequently reported a voice problem (38% vs. 26%, p<.05), acute (p<.05), and chronic (p<.05) voice problems, six specific voice symptoms, and five symptoms of physical discomfort. However, there were no gender differences in the perception that a voice problem adversely affected their current or future teaching career. For every type of course taught, women had a higher probability of reporting voice problems compared to men: odds ratio (OR) = 1.7-2.1. Compared with other courses, the teaching of physical education also was associated with an increased risk of developing a voice problem (OR = 3.7, 95% CI: 1.4-9.4) independent of gender, age, hours/day, or years taught. This is the first study to show that in the same occupation, females report a higher frequency of vocal symptoms than males even when teaching characteristics and years employment are similar.

Health status of the rural elderly according to farm work history: the Iowa 65 + rural health study.

In a geographically defined survey of 3,097 rural Iowans who were at least 65 yr of age, we examined the association between prior farm experience (greater than or equal to 25 yr) and various measures of current health status; we controlled for age, current working status, and, where appropriate, smoking and alcohol consumption. Health status was indexed by self-reported morbid conditions, symptoms, and physical function. After controlling for smoking behavior, it was found that both men and women with previous farm exposure currently experience a greater prevalence of all nine respiratory symptoms employed in the study relative to non-farmers. Farm men report a lower prevalence of Parkinson's disease and prostate conditions, but report a greater prevalence of stroke and a lower level of self-perceived health status. Women with a farm work history experience a greater level of physical function and fewer symptoms associated with mental illness. Overall significant benefits as well as risks associated with a history of farm work were identified. However, of those who survived to age 65, extended exposure to farm work did not have a major impact on the overall current health status of men and women.

The effect of uninephrectomy on mineral metabolism in normal human kidney donors.

A longitudinal prospective study of 17 normal human kidney donors before and after uninephrectomy revealed changes in mineral metabolism during compensation for loss of renal mass. Increases in carboxy terminal parathyroid hormone (PTH) and urinary cyclic adenosine monophosphate (AMP) occurred at 1 week and persisted for up to 3 years after surgery. 1,25(OH)2D levels fell from 26.5 +/- 2.0 to 18.6 +/- 1.7 pg/mL (P less than 0.05) at 1 week. Tubular reabsorption of phosphate (TRP) fell from 83.4% to 72.3% at 1 month and remained at this level throughout the study. At 6 months, several changes developed that were suggestive of increased PTH effect: hypocalciuria, a decrease in serum phosphate, and the return of 1,25(OH)2D levels to baseline or above. 1,25(OH)2D levels showed an inverse correlation with serum phosphate at 6 months (r = 0.75, P less than 0.005) and 1 year (r = 0.60, P less than 0.01). In addition, at 6 months, an increase in bone mineral content by forearm photon absorptiometry was indirect evidence for a period of positive calcium balance. The compensatory changes demonstrated in this study after loss of renal mass took place over the course of several months and persisted for up to 3 years.

Self-evaluated health and mortality among the elderly in New Haven, Connecticut, and Iowa and Washington counties, Iowa, 1982-1986.

The ability of global self-evaluations of health to predict survival in follow-up studies is tested in two samples of elderly, noninstitutionalized adults. Data from the Yale Health and Aging Project, New Haven, Connecticut (n = 2,812), and the 65+ Rural Health Study, Iowa and Washington counties, Iowa (n = 3,673), were used to investigate the association between 1982 self-evaluated global health status (excellent, good, fair, poor) and survivorship from 1982 to 1986. Despite extensive controls for physical health status in the form of measures of disabilities and chronic conditions, sociodemographic characteristics, and health risk behaviors at the beginning of the follow-up period, and the use of analytic techniques which take into account the stratified sample design of the New Haven data, poor self-perceptions of health significantly increase the risk of mortality. Adjusted odds ratios for the extreme categories ("poor" as compared with "excellent") for New Haven men and women were 5.33 (95% confidence interval (CI) 1.93-14.75) and 2.99 (95% CI 1.30-6.91), respectively; for Iowa men and women they were 4.84 (95% CI 2.22-10.57) and 3.16 (95% CI 1.49-6.71). Respondents reporting "fair" and "good" health also show elevated risks of mortality in dose-response fashion. Self-perceptions of health status appear to be a factor of unique prospective significance in mortality studies.

Correlates of forearm bone mass among women during maximal bone mineralization.

The distribution and correlates of bone mass among women ages 20-35 were studied. During young adulthood, bone mass reaches its maximum level and appears to stabilize. Factors that establish the individual's relative position in this plateau period may influence the ultimate expression of bone loss with aging. Mid-distal radial bone mass was measured in a geographically defined population of 86 women in two rural, demographically similar communities in Iowa. The water supplies provided 55 and 375 mg/liter of elemental calcium, generating significantly different mean community dietary calcium intakes of 871 and 1,233 mg/day, respectively. Bone mass was measured by single-beam photon densitometry and correlated with data from physical measurements, medical history, and reported nutritional intake. In evaluating the joint effect of variables in a multiple regression procedure, forearm bone mass was negatively and significantly associated with alcohol consumption (P = 0.0327) and with a first pregnancy prior to age 20 (P = 0.0250). There was a trend for current calcium intake estimated from 24-hr recall to be positively associated with bone mass (P = 0.0816). Because the 24-hr recall is characterized by significant error due to daily variability of an individual's intakes, a more general calcium intake was estimated from food frequency. Women whose estimated intake of calcium from food frequency was greater than 800 mg/day, the Recommended Daily Allowance, had significantly greater bone mass than women whose intake was estimated to be less than 800 mg/day (P = 0.0053). No relationship was observed with oral contraceptive use, parity, breastfeeding practices, smoking behavior, or measures of physical activity.