823
colleagues to support measures to curb smoking was laughed off the floor.4 We no longer keep myocardial infarction patients heavily sedated and in bed for several weeks, and we suspect that removal of dietary fibre, which had been the treatment for diverticular disease, is in fact its cause. The benefit of annual check-up, hitherto unquestioned in the United States, is now thought to be limited. The peer review offence is deviation per se, so it is no defence to show that an innovative treatment worked better than a standard one. Yet we are ethically and, in New York state, legally obliged to use our best judgment.5,6 In the absence of harm there is no cause of action for malpractice, while adherence to accepted medical practice which was not the doctor’s best judgment has been expressly rejected as a malpractice defence.6,7 Compelled adherence to authority, to dogma, is stultifying and profoundly deprofessionalising. Intellectual coercion is medieval and scholastic;8 gone are the Renaissance and the Enlightenment. Dissent becomes heresy; reputation, career, and livelihood go to the stake. At a time when millions of people have broken their shackles the medical profession is snapping them on. 17 Main Street, Sayville, NY 11782, USA 1.
Capsticks Solicitors, General Accident Building, 77/83 Upper Richmond Road,
BRIAN CAPSTICK PETER EDWARDS
London SW15 2TT, UK
Public health
reporting year
SIR,-Dr Dunlop (Aug 31, p 584) denigrates the use of the fiscal year for public health purposes in the UK. This is puzzling because directors of are
striving
public health and the National Health Service as a whole to strengthen the link between health and financial
information in their efforts
to
make the best
use
of funds. What is
important is for the same time period to be used for the fiscal and ROBERT CARLEN
Agramonte A. The inside story of a great medical discovery. Sci Monthly 1915 (Dec); I, 209-37. Reprinted in: Yellow fever studies: public health in America (New York:
Amo Press, Inc, 1977). 2. Anon. The New Encyclopedia Britannica, 15th ed, 1986. X: 627-28. 3. Crile G Jr. Surgery, in the days of controversy. JAMA 1989; 262: 256-58. 4. New York Times, July 19, 1990: D19. 5. Pike v Honsinger, 155 NY 201, 49 NE 760 (1898). 6. Toth v Community Hospital at Glen Cove 22 NY 2d 255; 292 NYS 2d 440 (1968). 7. Wickline v State of California, 239 Cal Rptr 810 (Cal App 2Dist 1986). 8. Osler W. Harvey and his discovery. In: The collected writings of Sir William Osler. Birmingham, Alabama: Classics of Medicine Library, 1985; see JAMA 1987; 258: 1522.
Defensive obstetric
midwives choose to "wait and see" when a trace is abnormal. If such a decision is not recorded, it will appear in retrospect as a negligent failure to respond. It is therefore necessary to record wait and see decisions, as well as decisions to intervene, as evidence that attention was being paid to the issue. It is increasingly difficult for obstetricians to resist the pressure for greater intervention, and a few measures of this type would go some way to reducing the pressure from litigation.
practice
SiR,—The obstetrician’s belief, reported by Dr Ennis and Dr Orr (Sept 7, p 616), that carrying out tests of uncertain reliability is somehow a shield against litigation is at odds with the experience of
legal team. major claims arise from the allegation that some abnormality in a test for fetal wellbeing was not acted upon in time. Where a test is inherently unreliable, or only reveals part of the clinical picture, there is a greater likelihood that no immediate action our
Most
will be taken on the basis of an aberration and thus a greater risk that the plaintiff, with the benefit of hindsight, will be able to seize on some adverse or merely equivocal result as the basis for a claim. The position is well illustrated by cardiotocography traces; far from being a shield against litigation these traces may well be a sword turned against the doctor. The volume of litigation suggests the following guidelines for electronic fetal heart monitoring
(EFHM): (1) Ascertain the reliability of results. One reason why EFHM has become a cause of litigation is the lack of consensus in the medical profession as to how far one may rely on its results as an indication of fetal distress. There is a great need for a prospective study to assess the reliability of EFHM as an indication of a poor outcome, whether or not in conjunction with fetal scalp blood sampling. (2) Train people in its use. Experts who deal with EFHM-related claims see many traces where the abnormality is both obvious and gross, yet no-one intervened. The explanation is sometimes that no-one believed the results (see above) and sometimes that no-one understood them. Methodical training with a clear message would avoid many instances of this second type. (3) Limit use to cases where EFHM is positively indicated and properly supported. There may be a case for limiting the use of EFHM to those instances where it is positively indicated and can be properly supported by trained staff, the availability of consultant advice, and facilities for fetal scalp blood sampling and for doing emergency caesarean sections. There is little benefit medically in the ritual use of equipment in cases where it is not likely to be needed and where facilities for interpreting the results and acting on them if a crisis develops are lacking. Legally, such a ritual is no benefit at all. (4) Record decisions to "wait and see". Because of the high proportion of false positives from EFHM, many doctors and
health information on which managers make their local decisions. The most practical way of achieving this is for the NHS to change to the fiscal year to fit in with most of the rest of the public sector. A well-designed information system should easily be able to provide figures for either time period, to please everyone. Dunlop’s objections in respect of cross-national studies would be more persuasive if he had cited examples, particularly in view of the imprecision of the data, where comparisons across fiscal and calendar years have led to different conclusions. Department of Public Health Medicine, North Bedfordshire Health Authority, Bedford MK40 2NU, UK
PAUL A. KITCHENER GARY JACKSON
Incidents in intensive
care
SIR,-A "critical incident" is just another name for an accident, and the underlying principles must be the same whether the accident involves an aircraft, a nuclear reactor, or an intensive-care unit. All accidents are due to human error, whether it is the designer of the aircraft, the manufacturer, or the pilot. Procedures are devised to ensure safe operation provided that the level of human performance exceeds an easily achievable level. There is an optimum state of arousal (ie, failure is more likely when the operator is either drowsy or in a state of panic) that is reduced as the task gets harder. The pilot generally gets the blame since there is only one of him and he is often dead, whereas the manufacturers are numerous and can afford the best lawyers. Take, for example, a landing with the undercarriage up. Here pilots are divided into two groups, those who have landed with their aircraft’s undercarriage up and those who have not done so, yet. In a jumbo jet it cannot be done; the undercarriage comes out automatically or the aircraft refuses to land. Reading the paper by Dr Wright and colleagues (Sept 14, p 676) I was struck that two of the five incidents discussed involved three-way taps. If these were of the small disposable variety, I think it fair to point out that they can be hard to read, and I would hate to think that a doctor carries a load of guilt or has a blighted career because of one of those things. Their design has not been brought to a level of perfection. After an accident there is always the feeling that with a little more care or better training it could have been avoided. I think this is wrong: we should blame the equipment. Could the equipment have been designed so that this accident would have been impossible? Nearly always the answer is "yes". Cherry Orchard, Marlow Common, Buckinghamshire SL7 2QP, UK
Use of cost-benefit analysis in material
BRENNIG
JAMES
promotional
SiR,—The question you raise in your Aug 17 editorial about the legality of pharmaceutical companies using cost-benefit data in their promotional material is intriguing and will no doubt be debated by others well versed in the relevant national and European Community legislation.
824
The desirability, however, of allowing cost-benefit data to be used for advertising is surely not in question. There is no dispute about the use of efficacy data since this forms part of the basis of applications for licensing by the Committee on Safety of Medicines. Pharmaceutical companies are required to publish the prices of their products and it seems ridiculous to prevent them from discussing the relation between these variables, for the products of their own or other companies. There is nothing to prevent doctors or clinical scientists publishing cost-benefit analyses of different approaches to the pharmacological treatment of symptoms or disease, and it is not logical to prevent pharmaceutical companies making use of this information in their advertising. Indeed, we are increasingly conscious of the fact that clinical endeavours are limited predominantly by money and clinicians are more than ever encouraged to examine the costs of their activities. Since expenditure in one clinical area denies funding to another it is unethical to do otherwise. Much of the stimulus and the funding to acquire cost-benefit information comes from the pharmaceutical industry and in my view it would be quite unreasonable to prevent these companies making use of the data obtained. There should of course be sanctions available for false claims, as there are for other information contained in promotional material.
variations of the prevalence of the disease and of the relevant number of sunshine hours. The largest group (ENE) showed no significant seasonal variation in the overall prevalence of open-angle glaucoma for either sex. There were twice as many women in this group as men (p < < 10-1°). Since there was no significant difference between the two distributions by sex for either type of glaucoma the data for both sexes were combined. However, the ENE group showed a significant variation for narrow/closed angle glaucoma, which correlated with that for sunshine hours (table). In contrast, the other two groups showed seasonal variations for open-angle glaucoma but the numbers for narrow/closed angle glaucoma were too small for statistical analysis. The results for the ENE group are consistent with the hypothesis. Those in the two other groups with open-angle glaucoma were unexpected. Group C shows a striking seasonal variation which just misses being significant, and it should be noted that the monthly variation of sunshine hours in the Caribbean region is negligible, compared with the conditions in the two other regions. Group SEA shows a powerful variation. Whether these results can be attributed to a photic effect on the development of the infant eye2 or to dietary effects in the later stages of pregnancy is uncertain. But it is noteworthy that a typically agerelated condition seems to be associated with events very early in life.
Department of Medicine, University Hospital of South Manchester,
I thank the surgeons and other
J. P. MILLER
Manchester M20 8LR, UK
Glaucoma and
season
of birth
SIR,-In comparison with age-matched caucasians, the Bantu tribe in South Africa shows only half the prevalence of narrow or closed angle glaucoma, presumably because their crystalline lenses are substantially thinner than those of caucasians.1 The lens may hence press less against the iris, and therefore compress the outflow channels of the aqueous humour less than would be true of lenses in caucasians, which are more liable to raise the intraocular pressure and so increase the chance of glaucoma. The mass of crystalline lenses in Nigerian neonatal pigs increases with birth occurring later in the dry season, but falls progressively the later it happens in the wet season.2 The postnatal rate of growth varies inversely with lenticular mass. If the thickness of the crystalline lens constitutes a predisposing factor for at least one type of glaucoma, and since, in one mammalian species, it varies with the season of birth, the prevalence of closed/narrow angle glaucoma might prove to vary with the patient’s date of birth. To test this hypothesis 701 patients were examined at Moorfields Eye Hospital, London. Diagnosis, date of birth, place of birth, ethnic group, and gender were recorded. Patients with open-angle, narrow-angle, or closedangle glaucoma were included, and they were classed according to their origin as south-east Asian (SEA), Europe and the near east (ENE), or the Caribbean region (C), to allow for local differences in sunshine hours,3 and monthly variations in births.4 The seasonality, if any, of the prevalence of glaucoma was tested as follows. The percentage of cases in any one sequence of six consecutive months (P) was compared with that in the remainder (Q), the total number of cases being n. The probability (p) of the test ratio being due to chance was calculated. The lowest p-value for any two pairs of complementary six-month periods was determined. A comparison was made also between monthly arguments (variations about the mean) of the seasonal
Moorfields Eye Hospital, London EC-1V 4JP, UK, and Age Concern Institute of King’s College London 1. Clemmesen
colleagues for their help.
Gerontology,
R. A. WEALE
V, Luntz MH. Lens thickness and angle-closure glaucoma. Acta
Ophthalmol 1976; 54:
193-97.
Alaku O, Steinbach J Effects of season of birth and age on eye lenses weight in pigs in the humid equatorial tropics. Growth 1982; 46: 22-25. 3. Houghton DD, ed Handbook of applied meteorology. New York: John Wiley, 1985. 4. Chambers R, Longhurst R, Paley A, eds. Seasonal dimensions to rural poverty London: Frances Pinter, 1981. 2
Fish oil and
psoriasis
SIR,-Dr Menter and Dr Barker’s review of the management of psoriasis (July 27, p 231) did not mention the role of dietary fish oil supplementation. Epidemiological studies have demonstrated a lower incidence of psoriasis in Greenland Eskimos than in European controls.1 This has been attributed to the Eskimo’s fishy diet which is high in n-3 fatty acids.2 Derivatives of arachidonic acid, especially leukotriene B4, have been implicated in the pathogenesis of psoriasis. Dietary supplementation with fish oil results in the generation of less inflammatory leukotrienes of the 5 series. Leukotriene Bs is a less potent stimulator of neutrophil chemotaxis3 and keratinocyte proliferation’ than leukotriene B4’ Clinical trials have demonstrated an improvement in psoriasis with the addition of fish oil to the patients regimen.5-7 Also, the hypotriglyceridaemic effect of fish oil may confer an additional benefit during combined therapy with etretinate. Department of Medicine, Division of Rheumatology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
GERALDINE MCCARTHY
= (P-Q)/ PQ/n
ANALYSIS OF SEASONAL PREVALENCES OF OPEN-ANGLE AND NARROW/CLOSED ANGLE GLAUCOMA IN THREE ETHNIC GROUPS
*1-12= Jan-Dec
tp=0033
Kromann N, Green A. Epidemiological studies m the Upernavik District, Greenland. Acta Med Scand 1989; 208: 401-06. 2. Dyerberg J, Bang HO, Stofferson HO, Moncada S, Vane J. Eicosapentaenoic acid prevention of thrombosis and atherosclerosis. Lancet 1978; ii: 117-19. 3 Lee TH, Mencia-Huerta J-M, Shih C, et al. Characterization and biologic properties of 5,12-dihydroxy derivatives of eicosapentaenoic acid, including leukotriene B5 and the double lipoxygenase product.J Biol Chem 1984; 259: 2383-89. 4. Kragballe K, Voorhees JJ, Goetzl EJ. Leukotnene B5 derivative from eicosapentaenoic acid does not stimulate DNA synthesis of cultural human keratinocytes but inhibits the stimulation induced by leukotriene B4. J Invest Dermatol 1985; 84: 349. 5. Bittiner SB, Cartwright I, Tucker WFG, Bleehen SS. A double-blind randomised placebo-controlled trial of fish oil in psoriasis. Lancet 1988; i: 378-80. 6. Ziboh VA, Cohen KA, Ellis CN, et al. Effects of dietary supplementation of fish oil on neutrophil and epidermal fatty acids. Modulation of clinical course of psoriatic subjects. Arch Dermatol 1986; 122: 1277-82. 7. Lassus AL, Dahlgren A-L, Halpern MJ, Sntalahti J, Happonen H-P. Effects of dietary supplementation with polyunsaturated ethyl ester lipids (Angiosan) in patients with psoriasis and psoriatic arthritis.J Int Med Res 1990; 18: 68-73. 1.
colleagues to support measures to curb smoking was laughed off the floor.4 We no longer keep myocardial infarction patients heavily sedated and in bed for several weeks, and we suspect that removal of dietary fibre, which had been the treatment for diverticular disease, is in fact its cause. The benefit of annual check-up, hitherto unquestioned in the United States, is now thought to be limited. The peer review offence is deviation per se, so it is no defence to show that an innovative treatment worked better than a standard one. Yet we are ethically and, in New York state, legally obliged to use our best judgment.5,6 In the absence of harm there is no cause of action for malpractice, while adherence to accepted medical practice which was not the doctor’s best judgment has been expressly rejected as a malpractice defence.6,7 Compelled adherence to authority, to dogma, is stultifying and profoundly deprofessionalising. Intellectual coercion is medieval and scholastic;8 gone are the Renaissance and the Enlightenment. Dissent becomes heresy; reputation, career, and livelihood go to the stake. At a time when millions of people have broken their shackles the medical profession is snapping them on. 17 Main Street, Sayville, NY 11782, USA 1.
Capsticks Solicitors, General Accident Building, 77/83 Upper Richmond Road,
BRIAN CAPSTICK PETER EDWARDS
London SW15 2TT, UK
Public health
reporting year
SIR,-Dr Dunlop (Aug 31, p 584) denigrates the use of the fiscal year for public health purposes in the UK. This is puzzling because directors of are
striving
public health and the National Health Service as a whole to strengthen the link between health and financial
information in their efforts
to
make the best
use
of funds. What is
important is for the same time period to be used for the fiscal and ROBERT CARLEN
Agramonte A. The inside story of a great medical discovery. Sci Monthly 1915 (Dec); I, 209-37. Reprinted in: Yellow fever studies: public health in America (New York:
Amo Press, Inc, 1977). 2. Anon. The New Encyclopedia Britannica, 15th ed, 1986. X: 627-28. 3. Crile G Jr. Surgery, in the days of controversy. JAMA 1989; 262: 256-58. 4. New York Times, July 19, 1990: D19. 5. Pike v Honsinger, 155 NY 201, 49 NE 760 (1898). 6. Toth v Community Hospital at Glen Cove 22 NY 2d 255; 292 NYS 2d 440 (1968). 7. Wickline v State of California, 239 Cal Rptr 810 (Cal App 2Dist 1986). 8. Osler W. Harvey and his discovery. In: The collected writings of Sir William Osler. Birmingham, Alabama: Classics of Medicine Library, 1985; see JAMA 1987; 258: 1522.
Defensive obstetric
midwives choose to "wait and see" when a trace is abnormal. If such a decision is not recorded, it will appear in retrospect as a negligent failure to respond. It is therefore necessary to record wait and see decisions, as well as decisions to intervene, as evidence that attention was being paid to the issue. It is increasingly difficult for obstetricians to resist the pressure for greater intervention, and a few measures of this type would go some way to reducing the pressure from litigation.
practice
SiR,—The obstetrician’s belief, reported by Dr Ennis and Dr Orr (Sept 7, p 616), that carrying out tests of uncertain reliability is somehow a shield against litigation is at odds with the experience of
legal team. major claims arise from the allegation that some abnormality in a test for fetal wellbeing was not acted upon in time. Where a test is inherently unreliable, or only reveals part of the clinical picture, there is a greater likelihood that no immediate action our
Most
will be taken on the basis of an aberration and thus a greater risk that the plaintiff, with the benefit of hindsight, will be able to seize on some adverse or merely equivocal result as the basis for a claim. The position is well illustrated by cardiotocography traces; far from being a shield against litigation these traces may well be a sword turned against the doctor. The volume of litigation suggests the following guidelines for electronic fetal heart monitoring
(EFHM): (1) Ascertain the reliability of results. One reason why EFHM has become a cause of litigation is the lack of consensus in the medical profession as to how far one may rely on its results as an indication of fetal distress. There is a great need for a prospective study to assess the reliability of EFHM as an indication of a poor outcome, whether or not in conjunction with fetal scalp blood sampling. (2) Train people in its use. Experts who deal with EFHM-related claims see many traces where the abnormality is both obvious and gross, yet no-one intervened. The explanation is sometimes that no-one believed the results (see above) and sometimes that no-one understood them. Methodical training with a clear message would avoid many instances of this second type. (3) Limit use to cases where EFHM is positively indicated and properly supported. There may be a case for limiting the use of EFHM to those instances where it is positively indicated and can be properly supported by trained staff, the availability of consultant advice, and facilities for fetal scalp blood sampling and for doing emergency caesarean sections. There is little benefit medically in the ritual use of equipment in cases where it is not likely to be needed and where facilities for interpreting the results and acting on them if a crisis develops are lacking. Legally, such a ritual is no benefit at all. (4) Record decisions to "wait and see". Because of the high proportion of false positives from EFHM, many doctors and
health information on which managers make their local decisions. The most practical way of achieving this is for the NHS to change to the fiscal year to fit in with most of the rest of the public sector. A well-designed information system should easily be able to provide figures for either time period, to please everyone. Dunlop’s objections in respect of cross-national studies would be more persuasive if he had cited examples, particularly in view of the imprecision of the data, where comparisons across fiscal and calendar years have led to different conclusions. Department of Public Health Medicine, North Bedfordshire Health Authority, Bedford MK40 2NU, UK
PAUL A. KITCHENER GARY JACKSON
Incidents in intensive
care
SIR,-A "critical incident" is just another name for an accident, and the underlying principles must be the same whether the accident involves an aircraft, a nuclear reactor, or an intensive-care unit. All accidents are due to human error, whether it is the designer of the aircraft, the manufacturer, or the pilot. Procedures are devised to ensure safe operation provided that the level of human performance exceeds an easily achievable level. There is an optimum state of arousal (ie, failure is more likely when the operator is either drowsy or in a state of panic) that is reduced as the task gets harder. The pilot generally gets the blame since there is only one of him and he is often dead, whereas the manufacturers are numerous and can afford the best lawyers. Take, for example, a landing with the undercarriage up. Here pilots are divided into two groups, those who have landed with their aircraft’s undercarriage up and those who have not done so, yet. In a jumbo jet it cannot be done; the undercarriage comes out automatically or the aircraft refuses to land. Reading the paper by Dr Wright and colleagues (Sept 14, p 676) I was struck that two of the five incidents discussed involved three-way taps. If these were of the small disposable variety, I think it fair to point out that they can be hard to read, and I would hate to think that a doctor carries a load of guilt or has a blighted career because of one of those things. Their design has not been brought to a level of perfection. After an accident there is always the feeling that with a little more care or better training it could have been avoided. I think this is wrong: we should blame the equipment. Could the equipment have been designed so that this accident would have been impossible? Nearly always the answer is "yes". Cherry Orchard, Marlow Common, Buckinghamshire SL7 2QP, UK
Use of cost-benefit analysis in material
BRENNIG
JAMES
promotional
SiR,—The question you raise in your Aug 17 editorial about the legality of pharmaceutical companies using cost-benefit data in their promotional material is intriguing and will no doubt be debated by others well versed in the relevant national and European Community legislation.
824
The desirability, however, of allowing cost-benefit data to be used for advertising is surely not in question. There is no dispute about the use of efficacy data since this forms part of the basis of applications for licensing by the Committee on Safety of Medicines. Pharmaceutical companies are required to publish the prices of their products and it seems ridiculous to prevent them from discussing the relation between these variables, for the products of their own or other companies. There is nothing to prevent doctors or clinical scientists publishing cost-benefit analyses of different approaches to the pharmacological treatment of symptoms or disease, and it is not logical to prevent pharmaceutical companies making use of this information in their advertising. Indeed, we are increasingly conscious of the fact that clinical endeavours are limited predominantly by money and clinicians are more than ever encouraged to examine the costs of their activities. Since expenditure in one clinical area denies funding to another it is unethical to do otherwise. Much of the stimulus and the funding to acquire cost-benefit information comes from the pharmaceutical industry and in my view it would be quite unreasonable to prevent these companies making use of the data obtained. There should of course be sanctions available for false claims, as there are for other information contained in promotional material.
variations of the prevalence of the disease and of the relevant number of sunshine hours. The largest group (ENE) showed no significant seasonal variation in the overall prevalence of open-angle glaucoma for either sex. There were twice as many women in this group as men (p < < 10-1°). Since there was no significant difference between the two distributions by sex for either type of glaucoma the data for both sexes were combined. However, the ENE group showed a significant variation for narrow/closed angle glaucoma, which correlated with that for sunshine hours (table). In contrast, the other two groups showed seasonal variations for open-angle glaucoma but the numbers for narrow/closed angle glaucoma were too small for statistical analysis. The results for the ENE group are consistent with the hypothesis. Those in the two other groups with open-angle glaucoma were unexpected. Group C shows a striking seasonal variation which just misses being significant, and it should be noted that the monthly variation of sunshine hours in the Caribbean region is negligible, compared with the conditions in the two other regions. Group SEA shows a powerful variation. Whether these results can be attributed to a photic effect on the development of the infant eye2 or to dietary effects in the later stages of pregnancy is uncertain. But it is noteworthy that a typically agerelated condition seems to be associated with events very early in life.
Department of Medicine, University Hospital of South Manchester,
I thank the surgeons and other
J. P. MILLER
Manchester M20 8LR, UK
Glaucoma and
season
of birth
SIR,-In comparison with age-matched caucasians, the Bantu tribe in South Africa shows only half the prevalence of narrow or closed angle glaucoma, presumably because their crystalline lenses are substantially thinner than those of caucasians.1 The lens may hence press less against the iris, and therefore compress the outflow channels of the aqueous humour less than would be true of lenses in caucasians, which are more liable to raise the intraocular pressure and so increase the chance of glaucoma. The mass of crystalline lenses in Nigerian neonatal pigs increases with birth occurring later in the dry season, but falls progressively the later it happens in the wet season.2 The postnatal rate of growth varies inversely with lenticular mass. If the thickness of the crystalline lens constitutes a predisposing factor for at least one type of glaucoma, and since, in one mammalian species, it varies with the season of birth, the prevalence of closed/narrow angle glaucoma might prove to vary with the patient’s date of birth. To test this hypothesis 701 patients were examined at Moorfields Eye Hospital, London. Diagnosis, date of birth, place of birth, ethnic group, and gender were recorded. Patients with open-angle, narrow-angle, or closedangle glaucoma were included, and they were classed according to their origin as south-east Asian (SEA), Europe and the near east (ENE), or the Caribbean region (C), to allow for local differences in sunshine hours,3 and monthly variations in births.4 The seasonality, if any, of the prevalence of glaucoma was tested as follows. The percentage of cases in any one sequence of six consecutive months (P) was compared with that in the remainder (Q), the total number of cases being n. The probability (p) of the test ratio being due to chance was calculated. The lowest p-value for any two pairs of complementary six-month periods was determined. A comparison was made also between monthly arguments (variations about the mean) of the seasonal
Moorfields Eye Hospital, London EC-1V 4JP, UK, and Age Concern Institute of King’s College London 1. Clemmesen
colleagues for their help.
Gerontology,
R. A. WEALE
V, Luntz MH. Lens thickness and angle-closure glaucoma. Acta
Ophthalmol 1976; 54:
193-97.
Alaku O, Steinbach J Effects of season of birth and age on eye lenses weight in pigs in the humid equatorial tropics. Growth 1982; 46: 22-25. 3. Houghton DD, ed Handbook of applied meteorology. New York: John Wiley, 1985. 4. Chambers R, Longhurst R, Paley A, eds. Seasonal dimensions to rural poverty London: Frances Pinter, 1981. 2
Fish oil and
psoriasis
SIR,-Dr Menter and Dr Barker’s review of the management of psoriasis (July 27, p 231) did not mention the role of dietary fish oil supplementation. Epidemiological studies have demonstrated a lower incidence of psoriasis in Greenland Eskimos than in European controls.1 This has been attributed to the Eskimo’s fishy diet which is high in n-3 fatty acids.2 Derivatives of arachidonic acid, especially leukotriene B4, have been implicated in the pathogenesis of psoriasis. Dietary supplementation with fish oil results in the generation of less inflammatory leukotrienes of the 5 series. Leukotriene Bs is a less potent stimulator of neutrophil chemotaxis3 and keratinocyte proliferation’ than leukotriene B4’ Clinical trials have demonstrated an improvement in psoriasis with the addition of fish oil to the patients regimen.5-7 Also, the hypotriglyceridaemic effect of fish oil may confer an additional benefit during combined therapy with etretinate. Department of Medicine, Division of Rheumatology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
GERALDINE MCCARTHY
= (P-Q)/ PQ/n
ANALYSIS OF SEASONAL PREVALENCES OF OPEN-ANGLE AND NARROW/CLOSED ANGLE GLAUCOMA IN THREE ETHNIC GROUPS
*1-12= Jan-Dec
tp=0033
Kromann N, Green A. Epidemiological studies m the Upernavik District, Greenland. Acta Med Scand 1989; 208: 401-06. 2. Dyerberg J, Bang HO, Stofferson HO, Moncada S, Vane J. Eicosapentaenoic acid prevention of thrombosis and atherosclerosis. Lancet 1978; ii: 117-19. 3 Lee TH, Mencia-Huerta J-M, Shih C, et al. Characterization and biologic properties of 5,12-dihydroxy derivatives of eicosapentaenoic acid, including leukotriene B5 and the double lipoxygenase product.J Biol Chem 1984; 259: 2383-89. 4. Kragballe K, Voorhees JJ, Goetzl EJ. Leukotnene B5 derivative from eicosapentaenoic acid does not stimulate DNA synthesis of cultural human keratinocytes but inhibits the stimulation induced by leukotriene B4. J Invest Dermatol 1985; 84: 349. 5. Bittiner SB, Cartwright I, Tucker WFG, Bleehen SS. A double-blind randomised placebo-controlled trial of fish oil in psoriasis. Lancet 1988; i: 378-80. 6. Ziboh VA, Cohen KA, Ellis CN, et al. Effects of dietary supplementation of fish oil on neutrophil and epidermal fatty acids. Modulation of clinical course of psoriatic subjects. Arch Dermatol 1986; 122: 1277-82. 7. Lassus AL, Dahlgren A-L, Halpern MJ, Sntalahti J, Happonen H-P. Effects of dietary supplementation with polyunsaturated ethyl ester lipids (Angiosan) in patients with psoriasis and psoriatic arthritis.J Int Med Res 1990; 18: 68-73. 1.
