- Email: [email protected]
Bone-density measurement
425
Bone-density measurement SIR,-We would like to respond to three misleading letters (Feb 8, p 370) commenting on the first issue of Effective Health Caré which had concluded that "given current evidence, it would be inadvisable to establish a routine population-based bone screening programme for menopausal women with the aim of preventing fractures". Dr Reid and Mr Purdie say that our report "relied heavily on grey literature"; as the bulletin clearly stated, its conclusions relied on a thorough evaluation of refereed published literature. The only exception was a detailed report of a working-party from Trent
region and which itself used published material. They also incorrectly state that the bulletin reports that the uptake of screening would be low; what we said was that "there is good reason to assume that even with a lot of effort uptake rate will not exceed 72 % ". This is just below the figure of 75% cited by Reid and Purdie from their studies, which are trials. The uptake in a routine screening programme would be expected to be lower. Dr Stevenson and his colleagues accuse us of not having considered the use of repeated measurements to assess the rate of bone loss. We devoted a whole paragraph to this issue (para 4.6). Purdie and Read bemoan the fact that they were not consulted and that their ongoing research was not reported. However, these bulletins are based on published work. It would be misleading and include research in progress unless it was near to publication and had something to add to the debate. The studies that Purdie and Reid organise have been running for less than 2 years and cannot yet have any relevant results since most fractures (especially of the hip) are experienced by women who are at least 15 years older than the women in their studies. If Purdie and Reid did have any substantive results that contradict our review they would surely have referred to them. The claim that no health authorities or other groups have been considering population bone screening is disingenuous. Drug companies and others have been very active in putting across the message in the media (including women’s magazines) that bone screening of healthy women around the time of the menopause is beneficial. This message is contained in literature from the influential osteoporosis screening and research unit at Guy’s Hospital, London, which states that, "it seems reasonable to suggest that all women should have a bone mass measurement, ideally at the time of the menopause". This pressure is felt by general practitioners and transmitted to health authorities. The decision to publish a bulletin on this topic was made by our steering group of general managers, directors of public health, and academics, in the light of this perceived pressure. Our aim was to help health authorities decide whether to invest in population bone screening for the prevention of fractures in elderly women. That we were responding to a real need is reflected by feedback from health authorities, 44 of which wrote to say that the bulletin addressed a topic that was "particularly relevant for their district or region at present". The fact that at least three UK trials are in progress presumably reflects considerable interest. In his letter Mr Kirkman tells us that in south Manchester a population bone screening programme is being piloted. Will those who claim to agree with our conclusions be as vociferous in their criticism of that premature attempt to introduce population screening as they have been of our
premature
to
bulletin? The organisers of two of the UK trials of screening attempt to use of a screening test without referring to sensitivity, specificity, and likely predictive value. That something is a risk factor, even a major one, for a disease does not automatically imply that it forms the basis of a good screening test (see cholesterol, for example). At least Stevenson, Kanis, and Christiansen do argue with the bulletin’s assessment of those test characteristics. We do not accept these criticisms and our estimates accord with those reported in the Trent study, of which Kanis was a coauthor. The assertion that our estimates of specificity and sensitivity of bone mineral density measurement are too low because other sites of fracture are more frequent is unfounded; prevalence does not influence these test characteristics. The debate about the duration of the protective effect of hormone-replacement therapy (HRT) after the cessation of
defend the
is unresolved but some epidemiological evidence does indicate a reduction in protection with time since HRT was stopped (after adjustment for age).3-5 The data on which Stevenson et al mainly base their argument provide no illumination because they refer to only one time point. The graph merely shows that women 6.6 years (on average) after stopping HRT have an average bone mineral content higher than that in those who received no treatment and lower than they had at the beginning of the study. What was the ratio when treatment stopped and how does it change over time? Even so, in estimating the impact of screening on the prevention of fractures (< 5%) we assumed that the protective effect did not diminish. If, as we suspect, it does, the impact is likely to be even lower. Being an "expert" on bone biology is not an automatic qualification to make judgments about screening. The history of medicine is littered with "experts" arguing for screening on the basis of their own enthusiasm to the neglect of the scientific, statistical, and public-health criteria on which screening programmes should be based. There is little in the three responses in your issue of Feb 8 to make us any more optimistic. treatment
TREVOR SHELDON ANDREW LONG NICK FREEMANTLE COLIN POLLOCK
Effective Health Care, School of Public Health, University of Leeds, Leeds LS2 9LN, UK
1. Effective Health Care 1992, no 1. Screening for osteoporosis to prevent fractures. School of Public Health, University of Leeds, 30 Hyde Terrace, Leeds LS2 9LN, UK. 2. Pitt F, Lloyd-Jones M, Brazier J, et al. The costs and benefits of screening and preventing post-menopausal osteoporosis in Trent region. Sheffield: Trent Osteoporosis Working Group, 1990. 3. Kiel D, Felson D, Anderson J, Wilson P, Moskowitz M. Hip fracture and the use of oestrogen in postmenopausal women. N Engl J Med 1987; 317: 1169-74 4. Weiss NS, Ure CL, Ballard JH, Williams AR, Daling JR. Decreased risk of fractures of the hip and lower forearm with postmenopausal use of estrogen. N Engl J Med
1980; 303: 1195-98.
Kreiger N, Kelsey JL, Holford TR, O’Connor T. An epidemiologic study of hip fracture in postmenopausal women. Am J Epidemiol 1982; 116: 141-48. 6. Holland W, Stewart S. Screening in health care. London: Nuffield Provincial Hospitals Trust, 1990. 5.
Headache
recurrence
after subcutaneous
sumatriptan SiR,—Sumatriptan is an effective and well-tolerated acute migraine.’ It has been licensed in several countries and was recently launched in Sweden for subcutaneous selfadministration via autoinjector. We have been assessing the efficacy and tolerability of this drug and the recurrence of headache after its use in patients at the Gothenberg migraine clinic. 50 consecutive patients (43 women and 7 men; mean age 47 [SD 8] and 35 [12] years, respectively; range 19-62) who met International Headache Society criteria for migraine either with (classic) or without (common) aura and who were eligible for treatment with sumatriptan were evaluated in an open 3-month follow-up study. Following local recommendations, patients were told to treat mild migraine headache with simple analgesics and to use sumatriptan when analgesics were insufficient or if they woke up with a fully developed migraine attack. The patients were informed about common adverse events of sumatriptan and trained in the handling of the autoinjector. They were told not to mix sumatriptan with any ergotamine-containing treatment. The first prescription consisted of six prefilled sumatriptan syringes (each 0-5 ml 6 mg) with an autoinjector; the instruction was to use only one injection per day (24 h). Follow-up was after 1 and 3 months. At the first follow-up visit all patients had treated themselves with two to six injections and not used more than one syringe per day. The autoinjector was well established by all but 2 patients, who found it difficult to trigger off. 48 patients rated the initial therapeutic efficacy as good or excellent; the other 2 were not that impressed by this treatment alternative. 26 out of the 48 responders (54%) had a recurrence of treatment for
=
their headache within 24 h. The average time to recurrence was 13 (SD 8) h (range 2-24) with the following distribution: 6 in 2-4 h, 4 in 6-8 h, 6 in 10-12 h, and 9 in 20-24 h. Sometimes the recurring headache was thought to be worse than the one the patient had had when the injection had been given.
Bone-density measurement SIR,-We would like to respond to three misleading letters (Feb 8, p 370) commenting on the first issue of Effective Health Caré which had concluded that "given current evidence, it would be inadvisable to establish a routine population-based bone screening programme for menopausal women with the aim of preventing fractures". Dr Reid and Mr Purdie say that our report "relied heavily on grey literature"; as the bulletin clearly stated, its conclusions relied on a thorough evaluation of refereed published literature. The only exception was a detailed report of a working-party from Trent
region and which itself used published material. They also incorrectly state that the bulletin reports that the uptake of screening would be low; what we said was that "there is good reason to assume that even with a lot of effort uptake rate will not exceed 72 % ". This is just below the figure of 75% cited by Reid and Purdie from their studies, which are trials. The uptake in a routine screening programme would be expected to be lower. Dr Stevenson and his colleagues accuse us of not having considered the use of repeated measurements to assess the rate of bone loss. We devoted a whole paragraph to this issue (para 4.6). Purdie and Read bemoan the fact that they were not consulted and that their ongoing research was not reported. However, these bulletins are based on published work. It would be misleading and include research in progress unless it was near to publication and had something to add to the debate. The studies that Purdie and Reid organise have been running for less than 2 years and cannot yet have any relevant results since most fractures (especially of the hip) are experienced by women who are at least 15 years older than the women in their studies. If Purdie and Reid did have any substantive results that contradict our review they would surely have referred to them. The claim that no health authorities or other groups have been considering population bone screening is disingenuous. Drug companies and others have been very active in putting across the message in the media (including women’s magazines) that bone screening of healthy women around the time of the menopause is beneficial. This message is contained in literature from the influential osteoporosis screening and research unit at Guy’s Hospital, London, which states that, "it seems reasonable to suggest that all women should have a bone mass measurement, ideally at the time of the menopause". This pressure is felt by general practitioners and transmitted to health authorities. The decision to publish a bulletin on this topic was made by our steering group of general managers, directors of public health, and academics, in the light of this perceived pressure. Our aim was to help health authorities decide whether to invest in population bone screening for the prevention of fractures in elderly women. That we were responding to a real need is reflected by feedback from health authorities, 44 of which wrote to say that the bulletin addressed a topic that was "particularly relevant for their district or region at present". The fact that at least three UK trials are in progress presumably reflects considerable interest. In his letter Mr Kirkman tells us that in south Manchester a population bone screening programme is being piloted. Will those who claim to agree with our conclusions be as vociferous in their criticism of that premature attempt to introduce population screening as they have been of our
premature
to
bulletin? The organisers of two of the UK trials of screening attempt to use of a screening test without referring to sensitivity, specificity, and likely predictive value. That something is a risk factor, even a major one, for a disease does not automatically imply that it forms the basis of a good screening test (see cholesterol, for example). At least Stevenson, Kanis, and Christiansen do argue with the bulletin’s assessment of those test characteristics. We do not accept these criticisms and our estimates accord with those reported in the Trent study, of which Kanis was a coauthor. The assertion that our estimates of specificity and sensitivity of bone mineral density measurement are too low because other sites of fracture are more frequent is unfounded; prevalence does not influence these test characteristics. The debate about the duration of the protective effect of hormone-replacement therapy (HRT) after the cessation of
defend the
is unresolved but some epidemiological evidence does indicate a reduction in protection with time since HRT was stopped (after adjustment for age).3-5 The data on which Stevenson et al mainly base their argument provide no illumination because they refer to only one time point. The graph merely shows that women 6.6 years (on average) after stopping HRT have an average bone mineral content higher than that in those who received no treatment and lower than they had at the beginning of the study. What was the ratio when treatment stopped and how does it change over time? Even so, in estimating the impact of screening on the prevention of fractures (< 5%) we assumed that the protective effect did not diminish. If, as we suspect, it does, the impact is likely to be even lower. Being an "expert" on bone biology is not an automatic qualification to make judgments about screening. The history of medicine is littered with "experts" arguing for screening on the basis of their own enthusiasm to the neglect of the scientific, statistical, and public-health criteria on which screening programmes should be based. There is little in the three responses in your issue of Feb 8 to make us any more optimistic. treatment
TREVOR SHELDON ANDREW LONG NICK FREEMANTLE COLIN POLLOCK
Effective Health Care, School of Public Health, University of Leeds, Leeds LS2 9LN, UK
1. Effective Health Care 1992, no 1. Screening for osteoporosis to prevent fractures. School of Public Health, University of Leeds, 30 Hyde Terrace, Leeds LS2 9LN, UK. 2. Pitt F, Lloyd-Jones M, Brazier J, et al. The costs and benefits of screening and preventing post-menopausal osteoporosis in Trent region. Sheffield: Trent Osteoporosis Working Group, 1990. 3. Kiel D, Felson D, Anderson J, Wilson P, Moskowitz M. Hip fracture and the use of oestrogen in postmenopausal women. N Engl J Med 1987; 317: 1169-74 4. Weiss NS, Ure CL, Ballard JH, Williams AR, Daling JR. Decreased risk of fractures of the hip and lower forearm with postmenopausal use of estrogen. N Engl J Med
1980; 303: 1195-98.
Kreiger N, Kelsey JL, Holford TR, O’Connor T. An epidemiologic study of hip fracture in postmenopausal women. Am J Epidemiol 1982; 116: 141-48. 6. Holland W, Stewart S. Screening in health care. London: Nuffield Provincial Hospitals Trust, 1990. 5.
Headache
recurrence
after subcutaneous
sumatriptan SiR,—Sumatriptan is an effective and well-tolerated acute migraine.’ It has been licensed in several countries and was recently launched in Sweden for subcutaneous selfadministration via autoinjector. We have been assessing the efficacy and tolerability of this drug and the recurrence of headache after its use in patients at the Gothenberg migraine clinic. 50 consecutive patients (43 women and 7 men; mean age 47 [SD 8] and 35 [12] years, respectively; range 19-62) who met International Headache Society criteria for migraine either with (classic) or without (common) aura and who were eligible for treatment with sumatriptan were evaluated in an open 3-month follow-up study. Following local recommendations, patients were told to treat mild migraine headache with simple analgesics and to use sumatriptan when analgesics were insufficient or if they woke up with a fully developed migraine attack. The patients were informed about common adverse events of sumatriptan and trained in the handling of the autoinjector. They were told not to mix sumatriptan with any ergotamine-containing treatment. The first prescription consisted of six prefilled sumatriptan syringes (each 0-5 ml 6 mg) with an autoinjector; the instruction was to use only one injection per day (24 h). Follow-up was after 1 and 3 months. At the first follow-up visit all patients had treated themselves with two to six injections and not used more than one syringe per day. The autoinjector was well established by all but 2 patients, who found it difficult to trigger off. 48 patients rated the initial therapeutic efficacy as good or excellent; the other 2 were not that impressed by this treatment alternative. 26 out of the 48 responders (54%) had a recurrence of treatment for
=
their headache within 24 h. The average time to recurrence was 13 (SD 8) h (range 2-24) with the following distribution: 6 in 2-4 h, 4 in 6-8 h, 6 in 10-12 h, and 9 in 20-24 h. Sometimes the recurring headache was thought to be worse than the one the patient had had when the injection had been given.