706
Letters
to
None of the four methods used a control group that had than. 50% of "good" control towns. Method m shows the least number of good controls (15%); this was the method Barraclough et al. chose to illustrate their results graphically. In method I, two of the control towns had Samaritan centres for part of the period when they were supposed not to have them. Sheffield and Bath had centres in 1965, when they served as controls for Birmingham and Oxford, respectively, over the years 1963, 1964, and 1965. Bristol had a centre for two of the three years when it was control for Reading. The median year for a centre being open, using the middle of the period in question, was computed. For method I, which used the experimental towns from Bagley’s original study,2 this was 1963. For n, III, and iv it was 1965. By mid-1965 there were more than twice as many centres in England and Wales as in mid-1963 (57 and 21, respectively). This supports Bagley’s suggestion that a national universality effect would particularly affect Barraclough’s results, national publicity and more
the Editor
SUICIDE PREVENTION BY THE SAMARITANS
SiR,-Dr Barraclough and his colleagues (July 30, p. 237) tested the hypothesis that Samaritan services prevent suicide. They took pairs of county boroughs matched by four difterent methods; an "experimental" town had a Samaritan centre open and remain open for three years, and its "control" town had no centre during that period. For each of the two, the percentage change between the suicide-rate averaged over the three years before the experimental town’s Samaritan centre opened and the average for the three years after the opening was computed. These percentage changes were compared and no significant differences were found between experimental and control groups formed by any of the four matching methods. For this approach to be valid, the experimental towns must have a Samaritan service and the control towns must not. Barraclough et al. assumed that this was so if the experimental towns had a centre, and the controls did not. However, as Dr Bagley pointed out (Aug. 13, p. 348) a town may have a Samaritan service if there is a Samaritan centre nearby. There may have been advertising and a local befriending group in the control town; certainly callers come from a region around a branch. Farnham, for example, has no Samaritans centre, but Guildford Samaritans receive a third of their calls from the Farnham/Aldershot district (10-15 miles from Guildford).’ I have examined the site of Samaritan centres near to control towns over the three-year period, using data kindly supplied by Dr Barraclough and his colleagues plus 1:250 000 Ordnance Survey maps. The criteria for deciding the year of opening were identical to those used by Barraclough et al. The table indicates the results of this analysis for each of the four matching methods used. It shows how many "control" towns had towns with Samaritan centres at a distance of 0-10 miles or 11-20 miles during the relevant period, and whether these centres were in existence for one, two, or all three years of that period. Distances were taken from town centre to town centre. Of all 106 pairings, for only 23% could the control be called "good", 40% of the controls had towns with Samaritan centres within 10 miles for all three years when they were assumed, by Barraclough et al., to be without a Samaritan service. They included, for example, Birkenhead, Bootle, and Wallasey as "controls" when the Samaritans of Liverpool and Merseyside centre was open. A further 38% of the controls could be deemed to have some service for all or part of the time; I chose 20 miles as the limit because most telephone calls within this distance are "local". Taking a less rigorous condition for a "good" controlnamely, a town deemed to have a service only if there is a town with a centre within 10 miles or less for all, or part, of the three years-we can still say that only 50% were good controls.
further reducing the efficacy of controls. It is a basic condition of the research design used in this study that the experimental group has the "treatment" and the control group does not. This requirement has not been met. Barraclough et al. conclude that their findings "must cast doubt on the scientific case for attributing the fall in the suicide rate to the work of the Samaritans". Whether there was or will be such a scientific case,2,3 and whether or not .such a case can be debated on the basis of this type of research approach, this particular study does not cast scientific doubts awareness
on
anything.
Winston Churchill Memorial Trust, 15 Queens Gate Terrace, London SW1 5PR
ANTHONY LAWTON
this letter has been shown to Mr Jennings, whose reply follows.-ED. L.
SIR,-Mr Lawton has shown that most of our control towns within 20 miles of a Samaritan centre. For this finding invalidate our results it would also need to be shown that Samaritan centres do reduce the suicide-rate in towns up to 20 miles away as well as in their own town. This is simply assumed by Lawton. There are, however, at least two reasons for doubting that this assumption is true. Firstly, not all individual towns showed a fall in their suicide-rate. If they had, Lawton’s findings would have been more important since no difference would be expected between Samaritan and control towns if all suicide-rates had declined to the same extent. In fact, however, 48% of Samaritan towns showed a rise in their suicide-rate despite the fact that most of them were within 20 miles of a Samaritan centre. A Samaritan centre, therefore, often does not reduce the suicide-rate in its own or in nearby towns. Secondly, since Bagley2 also used few "good" controls
were
to
2.
Bagley, C. Soc. Sci. Med. 1968, 2, 1. R. in Suicidology: Contemporary Developments (edited by Shneidman); chap. 17. New York, 1976.
3. Fox, 1.
Wilson, B. Personal communication. CONTROL TOWNS DISTANCE
*No centre within 20 miles throughout 3-year period. Figures in parentheses show numbers of towns.
(IN MILES) FROM TOWNS WITH SAMARITAN CENTRES (% ROUNDED UP)
E. S.
707
(20% in his first method, 33% in the second), it is hard to understand (if Lawton is correct) how he found a significant dif-
PRESUMED AND ATTEMPTED SUICIDES IN CAMBRIDGE
1961-70
ference between Samaritan and control towns and how, while most of his Samaritan towns showed a fall in their suicide-rate (67% in each method), most of his control towns showed a rise (80% in the first method, 67% in the second method) despite the fact that most were within 20 miles of a Samaritan centre. To test whether the use of "good" controls, by Lawton’s definition, would lead to a different result I found new controls for 14 of the 15 Samaritan towns used in methodt (no suitable control could be found for Oxford). This was done by matching on four components (as set out in our paper) but ensuring that the control towns were more than 20 miles from the nearest Samaritan centre throughout the comparison period. No significant difference was found between the Samaritan and the control towns. Lawton’s finding is not, therefore, sufficient to invalidate our results since there is no evidence that the suicide-rate of towns near Samaritan centres is affected by that
proximity.
are
based, will be published elsewhere.
’
M.R.C. Clinical
Psychiatry Unit, Graylingwell Hospital, Chichester, West Sussex, PO19 4PQ
33% of all those attempting suicide succeeded; in the last three years 23% succeeded. The picture is quite different in the younger age-group. In the first three years 11 % of those attempting suicide died but in the last three years only 3.5% of them died. Successful suicide is mostly to be found in the older age-groups but by far the majority of those attempting suicide are under 30 and very few of them die. We believe that if the Samaritans study attempted suicides before and after they became established in an area they might well find a difference. Some years ago one of us looked at such data for the Norwich area and for about three years after the Samaritans were established; there was little increase in attempted suicide when elsewhere it was steadily rising. After three years a further increase began but the gain of those three years was maintained. Attempted suicide is essentially exhaustion of the coping mechanism of the brain and is always potentially lethal. Even when, an hour or two later, they feel they could cope, and ask for help we may not succeed in saving them. Attempted suicide is the commonest medical illness causing people in their twenties to be admitted to hospital and is highly correlated with the so-called advances of civilisation. Tragically the developing countries are now following us along this downward path. years
I am grateful to Lawton for pointing out our error in using three towns as controls in method i when they had Samaritan centres themselves. I replaced these towns with new controls and found that the analysis now supported the null hypothesis even more strongly than before. The mean per cent change in the suicide-rate in the control towns fell from 3 -0 to -2.6. A full report of our study, including the data on which our results
CHRIS JENNINGS
StR,—There is constant confusion because of the different statistics given for suicides and attempted suicides. We think this has not been helped by the efforts to try and prove that Samaritans decrease the number of suicides. When a client approaches a Samaritan there is no way of knowing whether, without help, he or she might end up in the statistics of the suicides or the attempted suicides or neither. Indeed it is frequently a matter of chance whether someone who has taken an overdose lives or dies, depending on when they are found, how long it takes to get them to hospital and how easy it is to prevent the potentially lethal effect of the drug. One of us has seen a young woman within 20 min of her taking tablets and had her stomach washed out within 40 min, yet she died half an hour later from an epileptic fit followed by cardiac arrest. Published statistics for suicide in Britain show a progressive fall since 1963. However, the diagnosis of suicide is made by the coroner, and there is considerable variation in how events are interpreted by different coroners. We have studied all the available data including the pathologists’ reports on those who died of drug overdose or self-inflicted injury for the Cambridge area for the decade 1961-70. We have classed as presumed suicide those where there was clear medical evidence that the act was no accident (generous allowance for strange behaviour was made for elderly). The figures for presumed suicides shown in the table are medical assessments and not dependent upon the coroner’s verdict. They show a fall only after 1967. The table shows the numbers of suicides who were under 30 (excluding children under 10) and those who were 50 and over. The numbers in this older group were consistently about twice as great as the numbers in the younger population (in the population of East Anglia the 50+ group are almost exactly twice the 10-30 years age-group). The attempted suicides, however, show considerable differences. Only 13% of those attempting suicide in the Cambridge area succeeded over this decade. The attempted suicides aged 10-30 are nearly three times as many as those aged 50 and over. This ratio has changed over the decade. In the first three years the younger group was 1 -8 times the older one but in the last three years the under-30 group was 4-2 times the 50 and over group. In this older age-group in the first three
Department of Medicine, Addenbrooke’s Hospital, Cambridge CB2 2QQ
IVOR H. MILLS MARY A. M. HARRISON
DRUG PROPHYLAXIS IN PERTUSSIS
SIR,-I am astonished that Professor Arneil and Dr McAllister (July 2, p. 33) can recommend for pertussis prophylaxis in young infants a drug for which there is no proof of efficacy and which is contraindicated in the newborn. They suggest that infants who have been in contact with whooping-cough should be given antibiotic prophylaxis and that co-trimoxazole is the drug of choice. Erythromycin, ampicillin, chloramphenicol, and tetracyclines are mentioned as possible alternatives. The pharmacokinetics of co-trimoxazole is complex, and this drug should never be given as the agent of choice in young infants and it should never be used prophylactically. Trimethoprim blocks the metabolism of folic acid and should be given to the newborn in very severe cases only. Since no trial has shown that co-trimoxazole can eradicate Bordetella pertussis, it would be preferable to disregard the drug. Chloramphenicol and tetracyclines are effective, but are paediatricians going to prescribe these drugs in early infancy? Well-controlled trials have shown that ampicillin is no more effective than placebo in this indication.1.2 This leaves erythromycin. Erythromycin had the lowest 1. Bass, J. W., and others J. Pediat. 1969, 75, 768. 2. Islur, J., and others Clin. Pediat. 1975, 14, 171.
’
Letters
to
None of the four methods used a control group that had than. 50% of "good" control towns. Method m shows the least number of good controls (15%); this was the method Barraclough et al. chose to illustrate their results graphically. In method I, two of the control towns had Samaritan centres for part of the period when they were supposed not to have them. Sheffield and Bath had centres in 1965, when they served as controls for Birmingham and Oxford, respectively, over the years 1963, 1964, and 1965. Bristol had a centre for two of the three years when it was control for Reading. The median year for a centre being open, using the middle of the period in question, was computed. For method I, which used the experimental towns from Bagley’s original study,2 this was 1963. For n, III, and iv it was 1965. By mid-1965 there were more than twice as many centres in England and Wales as in mid-1963 (57 and 21, respectively). This supports Bagley’s suggestion that a national universality effect would particularly affect Barraclough’s results, national publicity and more
the Editor
SUICIDE PREVENTION BY THE SAMARITANS
SiR,-Dr Barraclough and his colleagues (July 30, p. 237) tested the hypothesis that Samaritan services prevent suicide. They took pairs of county boroughs matched by four difterent methods; an "experimental" town had a Samaritan centre open and remain open for three years, and its "control" town had no centre during that period. For each of the two, the percentage change between the suicide-rate averaged over the three years before the experimental town’s Samaritan centre opened and the average for the three years after the opening was computed. These percentage changes were compared and no significant differences were found between experimental and control groups formed by any of the four matching methods. For this approach to be valid, the experimental towns must have a Samaritan service and the control towns must not. Barraclough et al. assumed that this was so if the experimental towns had a centre, and the controls did not. However, as Dr Bagley pointed out (Aug. 13, p. 348) a town may have a Samaritan service if there is a Samaritan centre nearby. There may have been advertising and a local befriending group in the control town; certainly callers come from a region around a branch. Farnham, for example, has no Samaritans centre, but Guildford Samaritans receive a third of their calls from the Farnham/Aldershot district (10-15 miles from Guildford).’ I have examined the site of Samaritan centres near to control towns over the three-year period, using data kindly supplied by Dr Barraclough and his colleagues plus 1:250 000 Ordnance Survey maps. The criteria for deciding the year of opening were identical to those used by Barraclough et al. The table indicates the results of this analysis for each of the four matching methods used. It shows how many "control" towns had towns with Samaritan centres at a distance of 0-10 miles or 11-20 miles during the relevant period, and whether these centres were in existence for one, two, or all three years of that period. Distances were taken from town centre to town centre. Of all 106 pairings, for only 23% could the control be called "good", 40% of the controls had towns with Samaritan centres within 10 miles for all three years when they were assumed, by Barraclough et al., to be without a Samaritan service. They included, for example, Birkenhead, Bootle, and Wallasey as "controls" when the Samaritans of Liverpool and Merseyside centre was open. A further 38% of the controls could be deemed to have some service for all or part of the time; I chose 20 miles as the limit because most telephone calls within this distance are "local". Taking a less rigorous condition for a "good" controlnamely, a town deemed to have a service only if there is a town with a centre within 10 miles or less for all, or part, of the three years-we can still say that only 50% were good controls.
further reducing the efficacy of controls. It is a basic condition of the research design used in this study that the experimental group has the "treatment" and the control group does not. This requirement has not been met. Barraclough et al. conclude that their findings "must cast doubt on the scientific case for attributing the fall in the suicide rate to the work of the Samaritans". Whether there was or will be such a scientific case,2,3 and whether or not .such a case can be debated on the basis of this type of research approach, this particular study does not cast scientific doubts awareness
on
anything.
Winston Churchill Memorial Trust, 15 Queens Gate Terrace, London SW1 5PR
ANTHONY LAWTON
this letter has been shown to Mr Jennings, whose reply follows.-ED. L.
SIR,-Mr Lawton has shown that most of our control towns within 20 miles of a Samaritan centre. For this finding invalidate our results it would also need to be shown that Samaritan centres do reduce the suicide-rate in towns up to 20 miles away as well as in their own town. This is simply assumed by Lawton. There are, however, at least two reasons for doubting that this assumption is true. Firstly, not all individual towns showed a fall in their suicide-rate. If they had, Lawton’s findings would have been more important since no difference would be expected between Samaritan and control towns if all suicide-rates had declined to the same extent. In fact, however, 48% of Samaritan towns showed a rise in their suicide-rate despite the fact that most of them were within 20 miles of a Samaritan centre. A Samaritan centre, therefore, often does not reduce the suicide-rate in its own or in nearby towns. Secondly, since Bagley2 also used few "good" controls
were
to
2.
Bagley, C. Soc. Sci. Med. 1968, 2, 1. R. in Suicidology: Contemporary Developments (edited by Shneidman); chap. 17. New York, 1976.
3. Fox, 1.
Wilson, B. Personal communication. CONTROL TOWNS DISTANCE
*No centre within 20 miles throughout 3-year period. Figures in parentheses show numbers of towns.
(IN MILES) FROM TOWNS WITH SAMARITAN CENTRES (% ROUNDED UP)
E. S.
707
(20% in his first method, 33% in the second), it is hard to understand (if Lawton is correct) how he found a significant dif-
PRESUMED AND ATTEMPTED SUICIDES IN CAMBRIDGE
1961-70
ference between Samaritan and control towns and how, while most of his Samaritan towns showed a fall in their suicide-rate (67% in each method), most of his control towns showed a rise (80% in the first method, 67% in the second method) despite the fact that most were within 20 miles of a Samaritan centre. To test whether the use of "good" controls, by Lawton’s definition, would lead to a different result I found new controls for 14 of the 15 Samaritan towns used in methodt (no suitable control could be found for Oxford). This was done by matching on four components (as set out in our paper) but ensuring that the control towns were more than 20 miles from the nearest Samaritan centre throughout the comparison period. No significant difference was found between the Samaritan and the control towns. Lawton’s finding is not, therefore, sufficient to invalidate our results since there is no evidence that the suicide-rate of towns near Samaritan centres is affected by that
proximity.
are
based, will be published elsewhere.
’
M.R.C. Clinical
Psychiatry Unit, Graylingwell Hospital, Chichester, West Sussex, PO19 4PQ
33% of all those attempting suicide succeeded; in the last three years 23% succeeded. The picture is quite different in the younger age-group. In the first three years 11 % of those attempting suicide died but in the last three years only 3.5% of them died. Successful suicide is mostly to be found in the older age-groups but by far the majority of those attempting suicide are under 30 and very few of them die. We believe that if the Samaritans study attempted suicides before and after they became established in an area they might well find a difference. Some years ago one of us looked at such data for the Norwich area and for about three years after the Samaritans were established; there was little increase in attempted suicide when elsewhere it was steadily rising. After three years a further increase began but the gain of those three years was maintained. Attempted suicide is essentially exhaustion of the coping mechanism of the brain and is always potentially lethal. Even when, an hour or two later, they feel they could cope, and ask for help we may not succeed in saving them. Attempted suicide is the commonest medical illness causing people in their twenties to be admitted to hospital and is highly correlated with the so-called advances of civilisation. Tragically the developing countries are now following us along this downward path. years
I am grateful to Lawton for pointing out our error in using three towns as controls in method i when they had Samaritan centres themselves. I replaced these towns with new controls and found that the analysis now supported the null hypothesis even more strongly than before. The mean per cent change in the suicide-rate in the control towns fell from 3 -0 to -2.6. A full report of our study, including the data on which our results
CHRIS JENNINGS
StR,—There is constant confusion because of the different statistics given for suicides and attempted suicides. We think this has not been helped by the efforts to try and prove that Samaritans decrease the number of suicides. When a client approaches a Samaritan there is no way of knowing whether, without help, he or she might end up in the statistics of the suicides or the attempted suicides or neither. Indeed it is frequently a matter of chance whether someone who has taken an overdose lives or dies, depending on when they are found, how long it takes to get them to hospital and how easy it is to prevent the potentially lethal effect of the drug. One of us has seen a young woman within 20 min of her taking tablets and had her stomach washed out within 40 min, yet she died half an hour later from an epileptic fit followed by cardiac arrest. Published statistics for suicide in Britain show a progressive fall since 1963. However, the diagnosis of suicide is made by the coroner, and there is considerable variation in how events are interpreted by different coroners. We have studied all the available data including the pathologists’ reports on those who died of drug overdose or self-inflicted injury for the Cambridge area for the decade 1961-70. We have classed as presumed suicide those where there was clear medical evidence that the act was no accident (generous allowance for strange behaviour was made for elderly). The figures for presumed suicides shown in the table are medical assessments and not dependent upon the coroner’s verdict. They show a fall only after 1967. The table shows the numbers of suicides who were under 30 (excluding children under 10) and those who were 50 and over. The numbers in this older group were consistently about twice as great as the numbers in the younger population (in the population of East Anglia the 50+ group are almost exactly twice the 10-30 years age-group). The attempted suicides, however, show considerable differences. Only 13% of those attempting suicide in the Cambridge area succeeded over this decade. The attempted suicides aged 10-30 are nearly three times as many as those aged 50 and over. This ratio has changed over the decade. In the first three years the younger group was 1 -8 times the older one but in the last three years the under-30 group was 4-2 times the 50 and over group. In this older age-group in the first three
Department of Medicine, Addenbrooke’s Hospital, Cambridge CB2 2QQ
IVOR H. MILLS MARY A. M. HARRISON
DRUG PROPHYLAXIS IN PERTUSSIS
SIR,-I am astonished that Professor Arneil and Dr McAllister (July 2, p. 33) can recommend for pertussis prophylaxis in young infants a drug for which there is no proof of efficacy and which is contraindicated in the newborn. They suggest that infants who have been in contact with whooping-cough should be given antibiotic prophylaxis and that co-trimoxazole is the drug of choice. Erythromycin, ampicillin, chloramphenicol, and tetracyclines are mentioned as possible alternatives. The pharmacokinetics of co-trimoxazole is complex, and this drug should never be given as the agent of choice in young infants and it should never be used prophylactically. Trimethoprim blocks the metabolism of folic acid and should be given to the newborn in very severe cases only. Since no trial has shown that co-trimoxazole can eradicate Bordetella pertussis, it would be preferable to disregard the drug. Chloramphenicol and tetracyclines are effective, but are paediatricians going to prescribe these drugs in early infancy? Well-controlled trials have shown that ampicillin is no more effective than placebo in this indication.1.2 This leaves erythromycin. Erythromycin had the lowest 1. Bass, J. W., and others J. Pediat. 1969, 75, 768. 2. Islur, J., and others Clin. Pediat. 1975, 14, 171.
’
