Osteoporosis International. Original Article. Calcium Supplement and Bone Medication Use in a US Medicare Health Maintenance Organization

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1 Osteoporos Int (2002) 13: ß 2002 International Osteoporosis Foundation and National Osteoporosis Foundation Osteoporosis International Original Article Calcium Supplement and Bone Medication Use in a US Medicare Health Maintenance Organization B. Dawson-Hughes 1, S. S. Harris 1, G. E. Dallal 1, D. R. Lancaster 2, and Qi Zhou 2 1 Calcium and Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center, Boston, MA; and 2 Tufts Health Plan, Watertown, MA, USA Abstract. This study was conducted to determine the prevalence of the use of calcium supplements and of prescription medications to prevent or treat osteoporosis in men and women in a large New England Medicare Health Maintenance Organization (HMO). A two-page diet, medication use and medical history questionnaire was sent to a random sample of 9000 out of members and 2932 (32.6%) responded. Over 97% of the participants were Caucasian and 64.7% were female. The mean ages of the men and women were 74.4 Ô 5.8 and 74.6 Ô 6.2 years, respectively. Sixty-nine percent of the men and 59% of the women consumed two or fewer servings of dairy foods per day. Calcium supplement use was more prevalent among the women than the men (66.8% vs 24.9%, p50.001). and women with higher dairy food intakes were more likely to take calcium supplements than were those with lower dairy intakes. Prescription bone medications (including bisphosphonates, raloxifene and calcitonin) were used currently by 17.5% of the women and 2.3% of the men (p50.001). An additional 16.2% of the women currently took estrogen. Among the women, bone medication use did not change with age but estrogen use declined with increasing age. Among women age 80+ years, 15.6% used bone medications and 4.9% took estrogen. According to a national survey, more than half the US Caucasian female population over age 80 years has bone density low enough to warrant treatment under current guidelines. Based on the results of this survey, many Correspondence and offprint requests to: Bess Dawson-Hughes, MD, Calcium and Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center, 711 Washington Street, Boston, MA 02111, USA. Tel: +1 (617) Fax: +1 (617) HughesB@HNRC.Tufts.Edu elderly men and women may benefit from increased utilization of calcium supplements and bone-active medications. Keywords: Bone medication; Calcium; Estrogen; Health Maintenance Organization; Survey Introduction An increased intake of calcium and vitamin D has been shown to lower fracture rates in the elderly [1,2]. Despite this knowledge, dietary calcium and vitamin D intakes in this population remain far below recommended levels [3,4]. Supplementation is one means of closing the gap. From available information, it is difficult to determine the prevalence of calcium supplement use in general and, more importantly, the prevalence in relation to risk factors for osteoporosis. Effective prescription drugs are available to prevent and treat osteoporosis. Several organizations have offered guidelines as to who should be tested for osteoporosis and who should be treated. We have little information currently, however, on the demographic characteristics of patients who are actually being treated. Additionally, we do not know how many patients who are taking prescription drugs for osteoporosis prevention and treatment are also taking calcium supplements. The role of calcium in patients taking one of these drugs, estrogen, is important. Estrogen replacement therapy has a more positive effect on bone mineral density in postmenopausal women consuming an average of 1200 mg/day of calcium than in women consuming 600 mg/ day [5]. In a preliminary report, Honkanen et al. [6]

2 658 B. Dawson-Hughes et al. found that among postmenopausal women, calcium and estrogen were independently associated with a 30% lower risk of forearm fracture but that estrogen replacement and calcium combined were associated with a 70% lower risk. Comparable data on the effectiveness of other osteoporosis treatments with and without calcium are not available. In the clinical trials that established the anti-fracture efficacy of alendronate [7], risedronate [8,9], raloxifene [10] and calcitonin [11], supplemental calcium was administered to both the active and control arms. Because these drugs, like estrogen, act by reducing bone resorption, it is likely that their effectiveness depends to some extent upon the recipient s calcium intake. In this study, we report the results of a survey performed to determine the prevalence of calcium supplement and prescription bone medication use in men and women in a Medicare Health Maintenance Organization (HMO). We also examine associations of supplement use and bone medication use with each other, with age, and with other factors. Subjects and Methods Subjects The study participants were members of SecureHorizons-Tufts Health Plan for Seniors (THP-SH), a Medicare + Choice HMO. A random sample of 9000 members out of a total of members was selected from the THP-SH roster. Each selected member received a cover letter signed by the Medical Director of Secure Horizons and a 14-question questionnaire. Non-responders received one reminder postcard 2 weeks after the initial mailing. All materials were reviewed and approved by the Human Investigation Review Committee at Tufts University. A total of 2932 subjects (32.6%), 1068 men and 1836 women, returned the questionnaire to the Nutrition Center. Of these, 7 subjects were excluded because they were younger than 65 years of age, 28 because they did not indicate their sex, and 489 because they did not answer the question about frequency of calcium supplement use. Thus, 2408 members, 850 men and 1558 women, were included in the analyses. Data Collection Subjects were instructed to select the best answer from among those provided for each question on the questionnaire. They were asked how many servings per day of milk, yogurt and cheese they had consumed on average over the last month and how many days per week over the last month they had taken calcium supplements. Those who reported using calcium supplements were asked how much supplemental calcium per day they usually took (including the option of don t know ). Subjects were asked whether they had had a fracture since age 45 years and whether anyone had ever told them that they had osteoporosis. There were 4 questions about current medication/vitamin use, including multivitamin use, total number of prescription medications, estrogen use, and other prescription medications used to prevent broken bones (examples listed on the questionnaire were: Fosamax, Evista, Didronel, calcitonin and Actonel). only were asked about estrogen use. The remaining questions were related to subject demographics and other medical conditions. Data Analysis Except for age, which was collected as age in years, all quantitative study data were collected in the form of categories. Categories for most variables were condensed to provide sufficient sample sizes at each level. For example, calcium supplement dosages were grouped for the analysis as none, 1 499, , and mg/day of elemental calcium. In the analyses, two levels of calcium supplement use were considered, any use and 500 mg/day, a minimal effective dose. Three dairy intake categories (51 serving per day, 1 2 servings and 3+ servings) were computed from the milk, cheese and yogurt questions: one serving was 8 oz of milk or yogurt or 2 slices of cheese. Multivitamin use was categorized as none, less than daily and daily. Bivariate comparisons of the categorical variables were examined with the Crosstabs procedure and tested with the chi-square test. Relative risks and 95% confidence intervals were computed with the Crosstabs procedure, and interactions of sex with other variables were tested for statistical significance with logistic regression (SPSS, Chicago, IL). p values of were considered to indicate statistical significance. Sample sizes for various analyses differed due to missing data on the questionnaires, and are indicated in the tables. Results The age and sex distributions of the entire THP-SH population, the participants, and the non-participants are shown in Table 1. were more likely than men to participate. The male participants were 1.2 years older than the male non-participants (p ) but mean ages of the female participants and non-participants differed by only 0.1 years (not significantly different). The percentages of subjects who consumed 1, 1 2 and 3+ servings/day of dairy foods are shown in Table 2. Sixty-nine percent of the men and 59% of the women consumed 2 or fewer servings of dairy foods a day, an amount that would provide no more than 600 mg of calcium. Other clinical characteristics are shown in Table 2.

3 Calcium and Bone Medication Use in the Elderly 659 Table 1. Age and gender of THP-SH participants and non-participants Group n % Age Ô SD % Age Ô SD All Ô Ô 7.0 Participants 2408 a Ô Ô 6.2 Non-participants Ô 6.3 b,c Ô 7.0 b a Age known in only 2344 subjects. b Estimated assuming that the mean age of all 2408 participants equaled the mean age of participants with known age. c Compared with male participants, p Table 2. Subject characteristics Fig. 1. Calcium supplement use by dosage in 850 men and 1558 women. UA is unknown amount. Characteristic n Number % Caucasian Calcium supplement use (%) Any a 5500 mg/day a Dairy food intake (%) b serv/day a 1 2 serv/day serv/day Multiple vitamin use (%) 2200 None a 5Daily Daily Fracture since age 45 years a Ever told you have osteoporosis a Median no. of prescription medicines Bone medication use (%) a,c Estrogen use (%) a Differed significantly from men at p b Complete data were available for sample sizes of: milk 2289, cheese 2022 and yogurt Missing values for individual food items were assumed to be zero. c Includes 40 women who were also taking estrogen. The women were more likely than the men to use calcium supplements (Table 2). The amounts of supplemental calcium used by the men and women are shown in Fig. 1. The pattern of calcium supplement use in the men and women by age half-decades is shown in Fig. 2. Among the men, supplement use did not vary significantly with age. Among the women, however, the percentage taking any calcium supplements declined by about 20% across age half-decades. We next examined the pattern of supplement use according to dairy food consumption (Table 3). Although supplement use was more common among the women, the pattern of increasing supplement use with increasing dairy intake was similar in the men and the women (Table 3). Prescription bone medications were taken currently by 2.3% of the men and 17.5% of the women (p50.001); an additional 16.2% of the women were currently taking Fig. 2. Calcium supplement use (in any amount) by age half-decades in 833 men and 1511 women. Calcium supplement use differed across age groups in the women (p50.001) but not in the men (sex by age interaction significant at p = 0.003). estrogen (Table 2). The percentages of women using bone medications and estrogen, by age half-decades, are shown in Fig. 3. There were too few men taking bone medications (n = 17) to subdivide by age category. As seen in Fig. 3, the prevalence of bone medication use was fairly stable across the age half-decades, but estrogen use declined significantly with increasing age (p50.001). There were several predictors of calcium supplement and bone medication use. A personal history of a fracture since age 45 years was associated with more bone medication use in the men and the women (p50.001) (Table 4). Having been told they had osteoporosis was associated with more calcium supplement use in the women (p40.001) and with more bone medication use in the men and the women (p40.001) (Table 4). Multivitamin use, although more common in the women (Table 2), was a significant predictor of calcium supplement use in both sexes. Among subjects taking a multivitamin daily, 43.1% of the men and 86.3% of the women took some supplemental calcium. Among

4 660 B. Dawson-Hughes et al. Table 3. Calcium supplement use by category of dairy intake Any Ca supplement use a 5500 mg/day Ca supplement use a,b Dairy servings/day (n) % Relative risk 95% CI % Relative risk 95% CI 51 (92) 19.6 ref ref. 1 2 (484) (258) (118) 52.5 ref ref. 1-2 (781) (639) a Sex by dairy interaction not significant, p b Among subjects with known supplement dosages. Table 4. Osteoporosis-related predictors of calcium supplement and bone medication use History of fracture after age 45 years Yes No Using any calcium (%) Using bone medications (%) a 8 1 a Bone medication Estrogen 9 15 Ever told you have osteoporosis Fig. 3. Prevalence of bone medication use (black bars) and estrogen use (hatched bars) in 1424 women, by age half-decades. Estrogen use differed significantly across age groups (p50.001) but bone medication use did not. subjects who did not take multivitamins, only 4.3% of the men and 19.4% of the women took any supplemental calcium. In contrast, the prevalence of calcium supplement use did not vary significantly with the total number of prescription medications used currently. For example, 45.9% of the men and 50.3% of the women taking more than two prescriptions drugs reported taking supplemental calcium and 54.1% of the men and 49.7% of the women taking two or fewer prescription drugs took calcium supplements. Table 5 indicates the prevalence of calcium supplement use among men and women taking and not taking bone-active drugs. Two levels of calcium supplement use are considered: any and 500+ mg/day. and women taking bone medications were more likely to take calcium supplements (either any or mg/day) than men and women not taking bone medications. However, only 50.0% of the men and 77.7% of the women who took bone medications and 59.6% of the women who took estrogen were ingesting as much as 500 mg/day of supplemental calcium. Discussion Yes This study suggests that calcium supplements and medications that lower fracture risk are not being used by many older patients who could benefit from them, and that their use has not been well targeted to the individuals who might benefit most. Although our dietary calcium intake information is limited to dairy foods, national survey data indicate that the average calcium intake from non-dairy sources is less than 300 No Using any calcium (%) b Using bone medications (%) b 23 2 b Bone medication 49 7 Estrogen 8 15 a Fracture status significantly associated with use of calcium and bone medication (and, for women, estrogen), p b Ever told you have osteoporosis was significantly associated with use of calcium and bone medication (and, for women, estrogen) p

5 Calcium and Bone Medication Use in the Elderly 661 Table 5. Calcium supplement use by category of bone medication use Any Ca supplement us a 5500 mg/day Ca supplement use a,b Medication use (n) % Relative risk 95% CI % Relative risk 95% CI No treatment (729) 23.3 ref. 1.1 ref. Bone medication (17) No treatment (1029) 58.3 ref ref. Bone medication (247) Estrogen (192) a Sex by bone medication interaction not significant, p > b Among subjects with known supplement dosages. Table 6. Percentage of THP-SH members treated with bone-active drugs and the prevalence of low bone mineral density (T-score 572.5) in two surveys a Sex/age group THP-SH members treated (%) b c Prevalence of T-score in surveys (%) a T-score is defined as standard deviations from the young, same-sex reference mean. The survey data cited are: the National Health and Nutrition Examination Survey III of American Caucasian women [18] and the Dubbo study of Australian Caucasian men [19]. b For ages years. c The 2.3% is the average of all age groups (sample too small to divide). mg/day [12]. Thus it appears that the majority of our subjects had total calcium intakes of less than the recommended intake of 1200 mg/day [4]. This is consistent with the finding that median calcium intakes from food in the United States are only 50% (women) to 60% (men) of the amount recommended [3]. Calcium supplement use in our study population was more prevalent than that reported in the 1986 National Health Interview Survey (26% of women and 14% of men age 65 years and older) [13], probably for a combination of regional, secular and methodologic reasons. It is of note that subjects with low dairy calcium intakes were not the ones most likely to be taking calcium supplements. This is not the first documentation of such a mismatch. Others have reported that diets and other lifestyle characteristics of supplement users are typical of patterns associated with low risk of a variety of chronic diseases [14], and specifically that calcium supplement users have higher dietary calcium intakes than nonusers [14 16]. We have determined the percentages of men and women taking bone-active medications. We do not know the pattern of use in other populations, but we can compare the percentage of users in our study with the percentage of men and women expected to have bone mineral density (BMD) in the treatable range. The National Osteoporosis Foundation recommends that women age 65 years and older have bone density testing [17]. They found that treatment of women with BMD T- scores (defined as the number of standard deviations from the young sex-matched reference mean) of 2.5 and below is highly cost-effective [17], and in fact recommend treatment of women with T-scores above this level [17]. Table 6 shows the percentages of THP- SH participants currently taking bone-active drugs, and the percentages of American Caucasian women in the Health and Nutrition Examination Survey III who had T- scores [18]. The prevalences of low T-scores in males are from the Dubbo Study of Caucasian men in Australia [19]. Among the women in our study, there appears to be under-utilization of prescription bone medications overall and some mismatch of treatment to need by age category. Because low BMD is not the only indication for treatment, we cannot determine whether the younger women in our study may have been overtreated. We can, however, conclude that the older women were under-treated. Our finding that only 2.3% of men aged 65 years and older were being treated with bone medications clearly indicates that many men with BMD T-scores of 2.5 and below are not being treated. There are currently no established guidelines for bone density testing and treatment in men. The reasons for the low level of bone medication use are not clear. The fact that a fracture after age 45 years predicted use of bone medications indicates some recognition on the part of their physicians that a prior fracture is an important risk factor for osteoporosis [20]. In this population, we have no evidence that concurrent use of many prescription medications was a deterrent to bone medication use. and women on bone-active medications were more likely than untreated patients to be taking calcium supplements. Nonetheless, only half the men and twothirds to three-quarters of the women on these medications reported taking as much as 500 mg/day of supplemental calcium. The higher use of calcium with

6 662 B. Dawson-Hughes et al. bone medications than with estrogen may reflect the fact that estrogen is used for indications other than the prevention of osteoporosis. As indicated earlier, the antifracture efficacy of current treatments for osteoporosis can not be guaranteed in calcium-deficient subjects, so that it is important to ensure an adequate calcium intake in all men and women who are taking prescription drugs for osteoporosis. This study has several potential limitations. First, the response rate to the questionnaire was 32.9%, and we therefore cannot be certain that the sample is representative of the overall THP-SH membership. We did find that a disproportionately high percentage of women responded. This does not confound the results, however, since results are presented separately for men and women. The mean ages of the male and female participants were very similar to those of the nonparticipants, indicating representativeness with respect to this important characteristic. Comparability of other characteristics, notably socio-economic status, education and ethnicity, are unknown because of the unavailability of these data in HMO populations. If subjects in the present sample were less educated and/or of lower socioeconomic status than the larger population, existing literature suggests that our reported calcium supplement use would likely be underestimates of the true values [12]. We speculate that the reverse is more likely to be true: that participants are likely to be more educated and of higher socio-economic status than non-participants and that any bias is likely to be in the direction of overestimating calcium and bone medication use. Other limitations stem from the fact that the questionnaire was self-administered in the subjects homes and therefore, by necessity, the questions were limited in scope and subject to incomplete responses. In conclusion, this study suggests potentially productive avenues for reducing the risk for bone loss and fracture in elderly HMO patients. Specifically, since many patients have low calcium intakes and those who use calcium supplements are not necessarily those who need them most, it may be worthwhile to identify patients who are not obtaining recommended intakes and help them to do so. In addition, it appears that broader use of prescription bone medications, particularly among very elderly patients, may be warranted. Acknowledgements. This material is based on work supported by the US Department of Agriculture, under agreement No Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors, and do not necessarily reflect the view of the US Department of Agriculture. References 1. Chapuy MC, Arlot ME, Delmas PD, Meunier PJ. Effect of calcium and cholecalciferol treatment for three years on hip fractures in elderly women. BMJ 1994;308: Dawson-Hughes B, Harris SS, Krall EA, Dallal GE. Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older. N Engl J Med 1997; 337: Nusser SM, Carriquiry AL, Dodd KW, Fuller WA. A semiparametric transformation approach to estimating usual daily intake distributions. J Am Stat Assoc 1996;91: Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary reference intakes: calcium, phosphorus, magnesium, vitamin D, and fluoride. Institute of Medicine. 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Risk of new vertebral fracture in the year following a fracture. JAMA 2001;285: Received for publication 3 January 2002 Accepted in revised form 19 February 2002