CORRESPONDENCE 2
3
4
5
6
7
8
Lomas J. Promoting clinical policy change: using the art to promote the science in medicine. In: Anderson, Mooney, eds.The challenges of medical practice variations. London: Macmillan, 1989. NIH. Guidelines for the selection and management of consensus development conferences. Bethesda, MD: National Institutes of Health, 1983. Wortman PM, Vinokur A, Secherest L. Do consensus conferences work? A process evaluation of the National Institutes of Health consensus development program. J Hlth Politics Law 1989; 13(3): 469-498. Buch Andreasen P. Consensus conferences in different countries. Int J Hllh Care 1988; 4: 305-308. Casperie AF, Everingdon JE. Consensus development conferences in the Netherlands. Int J Tech Assessment Hlth Care 1985; 905-912. Guidelines for the management of asthma: 1 - chronic persistent asthma. Br Med J 1990; 301(6753): 651-654. Guidelines for the management of asthma in adults: II acute severe asthma. Br MedJ 1990; 301(6755): 797-800.
Senior Registrar in Public Health Medicine, Health Education Authority, Hamilton House, Mabledon Place, London WC1H 9TX
Yours faithfully Allyson Pollock
Quality assurance of medical care: reply Sirs, Alyson Pollock's letter raises a key question - what is the role of consensus development conferences in quality assurance? Unlike her, I do not believe that consensus conferences are an alternative to scientific evaluation of health care interventions. All that consensus techniques can do is to establish the current areas of agreement and disagreement and thus reveal those aspects about which there is significant uncertainty. This is of great value in that it indicates where future evaluative research should be directed. If one accepts that this is their principal role, then consensus conferences have an important contribution to make. On the other hand, there are dangers in suggesting that consensus equates with the true value of an intervention. The instability of consensus techniques can be demonstrated. In a recent study, we showed how the outcome of nominal groups is highly sensitive to definitions of agreement and disagreement adopted.1 I am not aware of similar research testing the sensitivity of consensus conference results. Finally, I do not think that those running consensus conferences should be too downhearted because of their lack of impact on health services. This is an unrealistic expectation. Instead, they should concentrate on using such a technique to help set research agenda for the
227
future. Until a great deal more resources are devoted to evaluation of the effectiveness, humanity and efficiency of interventions we shall continue to base our definitions of the quality of care on anecdote and opinion.
Reference 1
Scott EA, Black NA. When does consensus exist in expert panels? J Publ Hlth Med 1991; 13(1) 35-39.
Health Services Research Unit, Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E7HT
Yours faithfully Nick Black
Zinc supplementation during pregnancy Sirs, Smallness for dates has been shown'-2 to be associated with low zinc concentration in maternal leucocytes, and clinical experiments have shown that zinc deficiency leads to foetal growth retardation in late pregnancy. Nevertheless, in their controlled trial of zinc supplements in pregnancy, Mahomed el al? found no difference in outcome between 246 women given zinc supplementation and 248 women given a placebo. A small controlled trial which was conducted in Scunthorpe between February 1983 and July 1988 yielded more promising results, though the differences failed to reach statistical significance. The trial was undertaken in an attempt to solve the long-standing problem of high perinatal mortality rates in the Scunthorpe area, after two studies4-3 had shown that the excess in mortality was attributable to the high local incidence of low birthweight. For this reason, birthweight was selected as the principal measure of outcome.
Methods Letters explaining the trial, with consent forms attached, were distributed to all general practitioners in the District, with a request that they be issued to all women booking for antenatal care, and copies were also made available at antenatal clinics. Women resident in Scunthorpe Health District who booked for care before the 18th week of gestation, and who were booked for delivery at either Scunthorpe Maternity Home or at Scunthorpe General Hospital, were eligible to take part. Women who were eligible and who consented to take part were entered into the trial and allocated the first
Downloaded from https://academic.oup.com/jpubhealth/article-abstract/13/3/227/1537214 by INSEAD user on 29 March 2018
228
JOURNAL OF PUBLIC HEALTH MEDICINE
available trial number. As a result of prior random allocation, the numbers determined whether they would be given Supplement X or Supplement Y. Neither the medical and nursing staffnor the patients were informed which of these supplements contained zinc until the trial was completed. The supplements, prepared by Smith Kline and French, were spansules containing 150 mg of FeSO 4 and 0-5 mg of folic acid, to which 62 mg of zinc sulphide was added to make Supplement Y. Participants were asked to take one spansule per day. Haematological tests were undertaken on entering the study and at the 28th week of gestation.
Results It had been hoped to recruit 2000 women into the study over a period of 2-3 years. In the event, very few women chose to participate, apparently as a result of the effectiveness of earlier Health Education propaganda
against taking drugs during pregnancy. Fewer than 3 per cent of eligible women agreed to participate. Of 152 women allocated trial numbers, 12 withdrew on account of gastro-intestinal symptoms, two aborted, and two were delivered elsewhere. Two others failed to re-attend and are believed to have moved out of the district. Thus only 134 women completed the trial, 72 who were taking Supplement Y (with zinc) and 62 taking Supplement X. The characteristics of the two groups are compared in Table 1. There were more older women of higher parity in the group taking Supplement X, but a higher proportion of smokers and of teenagers in the group taking the zinc supplement. All the babies born to these participants were liveborn singletons. None died in the neonatal period, and none was reported to be malformed. The birthweight distribution is shown in Table 2.
TABLE 1 Comparison of subjects taking supplements X and Y 2
Parity at booking
0
1
3+
Total
Group X (Fe+folic acid)
24 (38-7%)
27 (43-5%)
6 (9-7%)
5(8-0)
62(100%)
Group Y (Fe, folic acid+Zn)
38 (53-5%)
27 (380%)
4 (5 6%)
2(2-8%)
71 (100%)*
Age at delivery (years) Under 19
20-24
25-29
Group X (Fe+folic acid)
2(3-2%)
21 (33 8%)
27 (43-5%)
Group Y (Fe, folic acid+Zn)
6 (8-4%)
29 (40-8%)
20 (28-2%)
Smoking
Non-smokers
Group X (Fe+folic acid)
49 (790%)
5(8-1%)
8(12-9%)
62
Group Y (Fe, folic acid+Zn)
44 (620%)
16(22-5%)
11 (15 5%)
7T
Alcohol
Non-drinkers
Occasional
Regular
n
Group X (Fe+folic acid)
30 (48 4%)
32 (51 -6%)
0 ( 0 0%)
62
Group Y (Fe, folic acid+Zn)
34 (47-9%)
36 (50-7%)
1 (1 -4%)
71*
1-9 Cigarettes/day
* Information on these details is not available for one woman in Group Y.
Downloaded from https://academic.oup.com/jpubhealth/article-abstract/13/3/227/1537214 by INSEAD user on 29 March 2018
30-34
35 +
n
6 (9-7%)
6 (9-7%)
62
13(18-3%)
3 ( 4 2%)
7T
10+
n
CORRESPONDENCE
229
TABLE 2 Comparison of birthweights of babies born to mothers taking alternative mineral supplements throughout the last six months of pregnancy Birthweight Nos weighing Nos weighing Nos weighing Nos weighing Total 3-8+ kg 3-4-3-799 kg 2-9-3-399 kg
3
4
5
6
7
8
Lomas J. Promoting clinical policy change: using the art to promote the science in medicine. In: Anderson, Mooney, eds.The challenges of medical practice variations. London: Macmillan, 1989. NIH. Guidelines for the selection and management of consensus development conferences. Bethesda, MD: National Institutes of Health, 1983. Wortman PM, Vinokur A, Secherest L. Do consensus conferences work? A process evaluation of the National Institutes of Health consensus development program. J Hlth Politics Law 1989; 13(3): 469-498. Buch Andreasen P. Consensus conferences in different countries. Int J Hllh Care 1988; 4: 305-308. Casperie AF, Everingdon JE. Consensus development conferences in the Netherlands. Int J Tech Assessment Hlth Care 1985; 905-912. Guidelines for the management of asthma: 1 - chronic persistent asthma. Br Med J 1990; 301(6753): 651-654. Guidelines for the management of asthma in adults: II acute severe asthma. Br MedJ 1990; 301(6755): 797-800.
Senior Registrar in Public Health Medicine, Health Education Authority, Hamilton House, Mabledon Place, London WC1H 9TX
Yours faithfully Allyson Pollock
Quality assurance of medical care: reply Sirs, Alyson Pollock's letter raises a key question - what is the role of consensus development conferences in quality assurance? Unlike her, I do not believe that consensus conferences are an alternative to scientific evaluation of health care interventions. All that consensus techniques can do is to establish the current areas of agreement and disagreement and thus reveal those aspects about which there is significant uncertainty. This is of great value in that it indicates where future evaluative research should be directed. If one accepts that this is their principal role, then consensus conferences have an important contribution to make. On the other hand, there are dangers in suggesting that consensus equates with the true value of an intervention. The instability of consensus techniques can be demonstrated. In a recent study, we showed how the outcome of nominal groups is highly sensitive to definitions of agreement and disagreement adopted.1 I am not aware of similar research testing the sensitivity of consensus conference results. Finally, I do not think that those running consensus conferences should be too downhearted because of their lack of impact on health services. This is an unrealistic expectation. Instead, they should concentrate on using such a technique to help set research agenda for the
227
future. Until a great deal more resources are devoted to evaluation of the effectiveness, humanity and efficiency of interventions we shall continue to base our definitions of the quality of care on anecdote and opinion.
Reference 1
Scott EA, Black NA. When does consensus exist in expert panels? J Publ Hlth Med 1991; 13(1) 35-39.
Health Services Research Unit, Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E7HT
Yours faithfully Nick Black
Zinc supplementation during pregnancy Sirs, Smallness for dates has been shown'-2 to be associated with low zinc concentration in maternal leucocytes, and clinical experiments have shown that zinc deficiency leads to foetal growth retardation in late pregnancy. Nevertheless, in their controlled trial of zinc supplements in pregnancy, Mahomed el al? found no difference in outcome between 246 women given zinc supplementation and 248 women given a placebo. A small controlled trial which was conducted in Scunthorpe between February 1983 and July 1988 yielded more promising results, though the differences failed to reach statistical significance. The trial was undertaken in an attempt to solve the long-standing problem of high perinatal mortality rates in the Scunthorpe area, after two studies4-3 had shown that the excess in mortality was attributable to the high local incidence of low birthweight. For this reason, birthweight was selected as the principal measure of outcome.
Methods Letters explaining the trial, with consent forms attached, were distributed to all general practitioners in the District, with a request that they be issued to all women booking for antenatal care, and copies were also made available at antenatal clinics. Women resident in Scunthorpe Health District who booked for care before the 18th week of gestation, and who were booked for delivery at either Scunthorpe Maternity Home or at Scunthorpe General Hospital, were eligible to take part. Women who were eligible and who consented to take part were entered into the trial and allocated the first
Downloaded from https://academic.oup.com/jpubhealth/article-abstract/13/3/227/1537214 by INSEAD user on 29 March 2018
228
JOURNAL OF PUBLIC HEALTH MEDICINE
available trial number. As a result of prior random allocation, the numbers determined whether they would be given Supplement X or Supplement Y. Neither the medical and nursing staffnor the patients were informed which of these supplements contained zinc until the trial was completed. The supplements, prepared by Smith Kline and French, were spansules containing 150 mg of FeSO 4 and 0-5 mg of folic acid, to which 62 mg of zinc sulphide was added to make Supplement Y. Participants were asked to take one spansule per day. Haematological tests were undertaken on entering the study and at the 28th week of gestation.
Results It had been hoped to recruit 2000 women into the study over a period of 2-3 years. In the event, very few women chose to participate, apparently as a result of the effectiveness of earlier Health Education propaganda
against taking drugs during pregnancy. Fewer than 3 per cent of eligible women agreed to participate. Of 152 women allocated trial numbers, 12 withdrew on account of gastro-intestinal symptoms, two aborted, and two were delivered elsewhere. Two others failed to re-attend and are believed to have moved out of the district. Thus only 134 women completed the trial, 72 who were taking Supplement Y (with zinc) and 62 taking Supplement X. The characteristics of the two groups are compared in Table 1. There were more older women of higher parity in the group taking Supplement X, but a higher proportion of smokers and of teenagers in the group taking the zinc supplement. All the babies born to these participants were liveborn singletons. None died in the neonatal period, and none was reported to be malformed. The birthweight distribution is shown in Table 2.
TABLE 1 Comparison of subjects taking supplements X and Y 2
Parity at booking
0
1
3+
Total
Group X (Fe+folic acid)
24 (38-7%)
27 (43-5%)
6 (9-7%)
5(8-0)
62(100%)
Group Y (Fe, folic acid+Zn)
38 (53-5%)
27 (380%)
4 (5 6%)
2(2-8%)
71 (100%)*
Age at delivery (years) Under 19
20-24
25-29
Group X (Fe+folic acid)
2(3-2%)
21 (33 8%)
27 (43-5%)
Group Y (Fe, folic acid+Zn)
6 (8-4%)
29 (40-8%)
20 (28-2%)
Smoking
Non-smokers
Group X (Fe+folic acid)
49 (790%)
5(8-1%)
8(12-9%)
62
Group Y (Fe, folic acid+Zn)
44 (620%)
16(22-5%)
11 (15 5%)
7T
Alcohol
Non-drinkers
Occasional
Regular
n
Group X (Fe+folic acid)
30 (48 4%)
32 (51 -6%)
0 ( 0 0%)
62
Group Y (Fe, folic acid+Zn)
34 (47-9%)
36 (50-7%)
1 (1 -4%)
71*
1-9 Cigarettes/day
* Information on these details is not available for one woman in Group Y.
Downloaded from https://academic.oup.com/jpubhealth/article-abstract/13/3/227/1537214 by INSEAD user on 29 March 2018
30-34
35 +
n
6 (9-7%)
6 (9-7%)
62
13(18-3%)
3 ( 4 2%)
7T
10+
n
CORRESPONDENCE
229
TABLE 2 Comparison of birthweights of babies born to mothers taking alternative mineral supplements throughout the last six months of pregnancy Birthweight Nos weighing Nos weighing Nos weighing Nos weighing Total 3-8+ kg 3-4-3-799 kg 2-9-3-399 kg
