A 'Water-Pill' Can Help Prevent a Broken Hip

Summarized by Robert W. Griffith, MD
January 29, 2004

Introduction

Hip fractures are common in the elderly, occurring mostly in people with osteoporosis. It happens that thiazide diuretic drugs, known as 'water pills', are widely used to treat high blood pressure in the elderly. And they slow the loss of calcium in the urine, allowing more calcium to remain in the body. This means they may have a protective effect on hip fractures. Scientists have analyzed data from the large Rotterdam Study, to see if this is indeed the case.

What was done

All the inhabitants over 55 in a particular suburb of Rotterdam, in the Netherlands, were invited to participate in a health study in 1990. Almost 8,000 people were enrolled and given a comprehensive medical work-up. Further interviews and medical exams were done at regular intervals for the next nine years. Computerized pharmacy records were used to analyze all medication usage during this time. All the participants were followed until they had a hip fracture, or died, or reached the end of the study in December 1999, whichever came first.

The scientists classified the use of thiazide drugs (including chlorthalidone¹) into one of 7 groups, according to how long the drugs were taken: never used; presently used for 1 day to 6 weeks; presently used for 6 weeks to 1 year; presently used for more than a year; stopped during the previous 8 weeks; stopped 8 weeks to 4 months previously; and stopped more than 4 months previously. The likelihood of hip fractures in each group of thiazide usage was then calculated.

What they found

There were 281 hip fractures in the 7,891 people in the 9-year study. The likelihood of having a hip fracture for those who had ever used thiazides and for those presently using thiazides - regardless of duration of use - were reduced, but the differences did not reach statistical significance (i.e. they might have occurred by chance alone).

For people currently using thiazides, the greater the length of use, the lower the risk of hip fracture; this calculation was statistically significant. And for those taking thiazides for more than a year, there was a significant reduction in risk to less than half the risk seen in non-users of these drugs.

The strongest protective effect of thiazides was seen in people over 80, but the effect was seen in all age groups. The subject's bone density measured at the start of the study didn't affect the results, but higher calcium intake was linked to a slightly lowered risk of fracture.

The good effect of thiazides persisted for a while after they were stopped, but it had disappeared within 4 months.

Comment

This effect of thiazide diuretics on hip fractures has been reported before, but this is the first study of the time needed for the drug to take effect, and of how long the benefit lasts after stopping the drug.

How do thiazides act in this way? As well as lessening calcium excretion in the urine, there may be an additional action; for instance, in this study there was a greater thiazide effect in those people with a higher calcium intake. Laboratory studies have shown that thiazides can have a direct effect on the boner-forming cells, the osteoblasts.

Whatever the mechanism, it's clear that thiazide water pills, widely recommended as basic treatment for high blood pressure, can significantly reduce the occurrence of hip fractures. They are relatively cheap and free from side effects, and probably deserve to be prescribed more often, instead of the newer, more expensive antihypertensive drugs.

Source

• Thiazide diuretics and the risk for hip fracture. MWCJ. Schoofs, M. van der Klift, A. Hofman,  et al., Ann Intern Med, 2003, vol. 139, pp. 476--482

Footnotes
1. Chlorthalidone is formally not a thiazide, but has similar effects on calcium excretion

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