Thiazide diuretic agents and the incidence of hip fracture

Calcium in the prevention and treatment of osteoporosis

Osteoporotic fractures have many sources. Low bone mass is one such, and inadequate calcium intake, in turn, is one of the causes of low bone mass. Calcium intake may be inadequate because it is low in its own right or, even if 'normal', it may not be sufficient to compensate for exaggerated obligatory losses. Inadequate calcium intake may cause bone mass to be low either because calcium intake during growth limits achievement of genetically programmed skeletal mass, or because low intake later in life aggravates involutional loss, or both. Ensuring a generous calcium intake throughout life will prevent both of these consequences. However, it is important to stress that even a calcium surfeit will not prevent or reverse bone loss due to inactivity, gonadal hormone deficiency, alcohol abuse or, indeed, any other factor. Calcium is a nutrient, not a drug. The only disorder it can be expected to alleviate is calcium deficiency. However, the evidence suggests that calcium deficiency is prevalent among Western populations, particularly in North America, and that it thereby contributes substantially to their osteoporotic fracture burden. This component of that burden is therefore entirely preventable.

Effect of calcium on skeletal development, bone loss, and risk of fractures

In assessing the role of calcium, it must be stressed that calcium is not the cause of bone health but simply a necessary condition for it. It is mechanical usage that is of primary importance for bone. In just the same way iron is essential for hemoglobin synthesis and protein is essential for muscle mass, but neither is sufficient by itself. What, then, ought we to expect from a high calcium intake? Can we prevent estrogen-withdrawal bone loss? No. Calcium is not a substitute for estrogen, anymore than it is a substitute for exercise. Will calcium slow the remodeling loss that occurs with aging? Yes, to some extent; as calcium slows remodeling, it will inevitably slow remodeling-related loss. But most importantly, a high calcium intake will prevent calcium-deficiency bone loss. The only question, therefore, is the extent to which calcium deficiency loss may contribute significantly to bone fragility in various populations. The bone loss and fracture data reviewed briefly here indicate that an important portion of the osteoporotic fracture burden is calcium-related. What that portion is will be a function of the fraction of the population with inadequate intakes in any given country. Better than half of all adult American women have calcium intakes less than 500 mg/day, whereas only a small fraction of Dutch or Danish women, for example, would be under that level. Hence, a population-wide program to increase calcium intake in the United States would be likely to yield a greater benefit than in either the Netherlands or Denmark. That does not mean, of course, that there could not be substantial benefit to individuals with low intakes in all countries. Calcium intakes of greater than or equal to 1,500 mg are both safe and natural. While not all bone loss and low trauma fractures are due to low calcium intake, some almost certainly are. Adaptation to low intakes does occur, but it is seldom sufficient to compensate for the low intake. We cannot easily distinguish those who need more calcium from those who need less, and for that reason it makes good sense to ensure an adequate calcium intake for the entire adult population. What should that intake be? During adolescence, 1,500 mg will come close to ensuring the achievement of genetically programmed levels of peak bone mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Interpretation of bone mass determinations as they relate to fracture: implications for asymptomatic primary hyperparathyroidism

Determination of bone mass is currently the most clinically useful measurement of bone strength and of fracture risk. Interpretation of bone mass determination as it relates to fracture has been developed largely from studies of age-related bone loss. A decrease in bone mass and an increase in fracture incidence with aging are universal phenomena that are causally related by virtue of the major contribution bone mass makes to skeletal strength. Over 70% of the skeleton's strength to resist fracture resides in its mineral content in vitro. Clinically, the relationship between trauma and fracture is complex, and in the general population, fracture appears as a random event occurring more frequently as bone mass decreases. In the individual, measurement of bone mass in relation to the range of bone mass and the fracture incidence of the reference population provides an estimate of the risk of sustaining a fracture in the future. In primary hyperparathyroidism, interpretation of a bone mass determination must take into account the effect of the disease activity on the skeleton against the background of universal age-related changes in bone mass and fracture incidence. This general relationship is likely to be altered by at least three unique effects that parathyroid hormone may have on the skeleton: (1) parathyroid hormone has a differential effect on cortical and cancellous bone; (2) it has a biphasic effect on bone that is concentration dependent; and (3) it alters bone quality and architecture.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-trauma mortality in elderly women with low bone mineral density. Study of Osteoporotic Fractures Research Group

9704 ambulatory women aged 65 years or older were prospectively studied to determine whether low bone mineral density (osteopenia) was associated with mortality. Bone mineral density was measured at entry to the study by single-photon absorptiometry. 299 women died during a mean of 2.8 years' follow-up. Osteopenia was associated with increased non-trauma mortality, probably because it is a marker for several other adverse factors. Each standard deviation decrease in proximal radius bone mineral density (0.104 g/cm2) was associated with a 1.19-fold increase in mortality (95% confidence interval 1.04-1.36), adjusted for age and duration of follow-up. Diminished bone mineral density at the proximal radius was strongly associated with deaths from stroke (relative risk = 1.74; 95% CI 1.12-2.70), an association that was not confounded by history of previous stroke, hypertension, postmenopausal use of oestrogen, thiazide diuretic treatment, diabetes mellitus, and smoking. Most deaths in women with low bone mineral density are unrelated to the occurrence of fractures-an observation that should be taken into account when estimating the need for and cost-effectiveness of bone-density screening and fracture prevention programmes.

Risk factors for falls as a cause of hip fracture in women. The Northeast Hip Fracture Study Group

BACKGROUND

Although even in the elderly most falls are not associated with fractures, over 90 percent of hip fractures are the result of a fall. Few studies have assessed whether the risk factors for falls are also important risk factors for hip fracture.

METHODS

To examine the importance of risk factors for falls in the epidemiology of hip fracture, we performed a case-control study of 174 women (median age, 80 years) admitted with a first hip fracture to 1 of 30 hospitals in New York and Philadelphia. Controls, matched to the case patients according to age and hospital, were selected from general surgical and orthopedic surgical hospital services. Information was obtained by direct interview.

RESULTS

As measured by the odds ratio, increased risks for hip fracture were associated with lower-limb dysfunction (odds ratio = 1.7; 95 percent confidence interval, 1.1 to 2.8), visual impairment (odds ratio = 5.1; 95 percent confidence interval, 1.9 to 13.9), previous stroke (odds ratio = 2.0; 95 percent confidence interval, 1.0 to 4.0), Parkinson's disease (odds ratio = 9.4; 95 percent confidence interval, 1.2 to 76.1), and use of long-acting barbiturates (odds ratio = 5.2; 95 percent confidence interval, 0.6 to 45.0). Of the controls, 44 (25 percent) had had a recent fall. The case patients were more likely than these controls to have fallen from a standing height or higher (odds ratio = 2.4; 95 percent confidence interval, 1.0 to 5.7). Of those with hip fracture the younger patients (less than 75 years old) were more likely than the older ones (greater than or equal to 75 years old) to have fallen on a hard surface (odds ratio = 1.9; 95 percent confidence interval, 1.04 to 3.7).

CONCLUSIONS

A number of factors that have been identified as risk factors for falls are also associated with hip fracture, including lower-limb dysfunction, neurologic conditions, barbiturate use, and visual impairment. Given the prevalence of these problems among the elderly, who are at highest risk, programs to prevent hip fracture should include measures to prevent falls in addition to measures to slow bone loss.

Hydrochlorothiazide versus spironolactone: long-term metabolic modifications in patients with essential hypertension

The metabolic side effects of thiazide diuretics are believed to be responsible for the failure of thiazide diuretics to reduce cardiovascular morbidity in patients with hypertension. However, the decrease in the incidence of osteoporotic fractures that are associated with thiazide administration may be relevant in elderly patients with arterial hypertension. Spironolactone (SP) appears not to influence the metabolic risk profile of the patient with hypertension, and no studies have examined its effect on calcium metabolism. Therefore, in 22 patients with mild to moderate essential hypertension, the authors performed a parallel, randomized, double-blind, placebo-controlled study that compared the effects on serum urate and lipid, potassium, magnesium, and calcium metabolism of hydrochlorothiazide (HC) (mean [+/- SD] dose, 72 +/- 26 mg/d) and SP (144 +/- 53 mg/d) during a 52-week period. As compared with placebo, HC significantly increased serum urate and total cholesterol concentrations, and decreased serum potassium levels. SP did not affect serum urate or cholesterol levels but increased serum potassium concentrations. Neither diuretic significantly modified magnesium metabolism. Little changes were seen in serum calcium levels during HC or SP treatment, whereas urinary calcium excretion was significantly decreased by HC (mean decrease, 45%; P less than .01) or SP (40%; P less than .01). The authors conclude that SP, in addition to its potassium-sparing properties, has a calcium-sparing effect that may be beneficial for patients in whom reduction of urinary calcium excretion has a therapeutic value.

Practical considerations in treating the elderly hypertensive patient

More than half of all older Americans die of cardiovascular diseases. Hypertension is a major risk factor for cardiovascular diseases, and its prevalence increases with age. Older patients are both at higher risk for end-organ complications and less likely than younger ones to survive such complications as myocardial infarction and stroke. Clinical studies have shown that reduction of elevated blood pressure is beneficial in many older persons. Optimal selection of antihypertensive therapy requires consideration of the special characteristics of the elderly, who differ from their younger counterparts in physiology, response to therapy and frequency of concomitant illnesses and medications. Calcium antagonists are particularly effective in these patients; other agents are useful in selected situations. Drugs that are likely to cause central nervous system side effects or orthostatic hypotension generally should be avoided in this patient population. Therapy should begin with a low dose and be titrated upward slowly, thus avoiding excessive reduction of blood pressure and the development of orthostatic hypotension. Treatment should be altered as necessary to minimize side effects that may impair quality of life or lead to poor compliance.

Neuropsychiatric considerations in the treatment of hypertension

Algorithms have been developed to guide the treatment of simple hypertension. The basic algorithms are modified in the face of concurrent medical conditions, taking into account the various pharmacological effects of antihypertensive agents. This article reviews the neuropsychiatric effects of the major classes of antihypertensive agents (ganglionic blockers, centrally acting agents, diuretics, vasodilators, beta-blockers, calcium channel blockers and angiotensin converting enzyme inhibitors). The purported efficacy of some antihypertensive agents in the treatment of psychiatric conditions is also discussed. Beneficial as well as adverse neuropsychiatric effects are reviewed. In this way, guidelines for the treatment of hypertension are suggested which take into account a broad spectrum of neuropsychiatric considerations.

Lifelong calcium intake and prevention of bone fragility in the aged

Primary prevention of osteoporosis involves achieving the full genetic potential for bone mass. Secondary prevention is concerned with protecting what bone mass a woman may have at her current age. Calcium plays an important role in both. Calcium requirement varies with stage of growth, with physiological drains (e.g., pregnancy and lactation), and with factors that influence absorption and excretory loss (e.g., gonadal hormone status and sodium and protein intakes). The evidence is strong that prevailing calcium intakes contribute to the low bone mass component of osteoporotic fragility and that increases in intake would reduce the osteoporotic fracture burden. At the same time it needs to be emphasized that bone health is a multifactorial affair and that meeting calcium requirements alone will neither guarantee optimal bone growth nor protect against bone loss if other critical factors are missing. For example, calcium affords only minimal protection against either immobilization or estrogen withdrawal bone loss. Thus, while assuring an adequate calcium intake remains a sound strategy, it cannot be considered a total preventive for osteoporosis.

Effect of thiazide on rates of bone mineral loss: a longitudinal study

OBJECTIVE

To determine the effect of thiazide diuretic drugs on rates of bone mineral loss.

DESIGN

Longitudinal, observational study with a mean follow up of five years.

SETTING

Hawaii Osteoporosis Center, Honolulu.

SUBJECTS

1017 Japanese-American men born between 1900 and 1920, of whom 378 were treated for hypertension (study group) and 639 did not have hypertension (control group).

INTERVENTION

Thiazide diuretics were taken by 325 men for a mean of 11.9 years; 53 men took antihypertensive drugs other than thiazides.

MAIN OUTCOME MEASURE

Rate of bone loss estimated from serial photon absorptiometric scanning at three skeletal sites (calcaneus, distal radius, and proximal radius).

RESULTS

Rates of bone loss at all three sites were significantly reduced among thiazide users when compared with controls. The reductions in loss rate ranged from 28.8% (p = 0.02) (distal radius) to 49.2% (p = 0.0005) (calcaneus) relative to the controls. At all three sites the men taking other antihypertensive drugs had faster loss rates (22.6-43.1%) than those of the controls but the difference was significant only for the distal radius.

CONCLUSION

Thiazide diuretics slow the rate of bone loss in elderly men.