- Email: [email protected]
MONTH OF BIRTH AND PREVALENCE OF MUSCULOSKELETAL DISEASES LATER IN LIFE
739
Fig 1-Clinical presentation of B19 infection.
SIR,-Dr Lefrere and Dr Courouce suggest that laboratories which diagnose human parvovirus B19 should report B19 cases, to establish an epidemiological profile. A lack of B19 antigen means that few centres can serologically diagnose B19 infection. No method for propagating this virus in cell culture has been established, and diagnostic tests for anti-B19 IgM and IgG rely on blood obtained during the viraemic phase of infection. Large-scale screening of blood donations or of people who have been in contact with B19-affected patients is still the only way to obtain sufficient antigen. We screened 160 blood units from the Munich Red Cross Blood Transfusion Service by DNA spot hybridisation with a 32P-Iabelled cloned DNA fragment of the B19 genome (PgemPTMl, kindly provided by H. Wolf, Munich), and found one positive blood unit from a symptomless donor. With this unit, an ELISA system for routine detection of anti-B19 IgM and IgG has been established. Sera (n=76) from children aged 1-15 years admitted to the paediatric unit of the University of Munich and from blood donors (n 692) aged 18-68 were tested for anti-B 19 IgM. The prevalence of anti-B19 IgG is shown in the table. =
"Other" includes abnormalliver(funcaontests,) glandular Ifever,l factor VIII treatment, intrauterine infection, and neuralgic amyotrophy.
PREVALENCE OF
ANTI-B19 IgG IN SERA OF CHILDREN (n BLOOD DONORS
In
sera
=
76) AND
(n = 692)
(n = 400) from patients with clinical indications of B 19
infection, mainly from southern Germany and Austria, between July, 1986, and February, 1987, we detected anti-B19 IgM in 52 and viral B19 DNA in one case. The clinical diagnoses of the IgM positive cases were: erythema infectiosum (15), atypical erythema (28), hydrops fetalis (2), enteritis (2), juvenile chronic polyarthritis (1), arthralgia (1), transient anaemia (1), lymphadenitis (1), and acute atypical dermatomyositis (1). An additional 300 sera from pregnant women, dialysis patients, and vaccinated medical students, examined primarily for hepatitis B markers, were tested for anti-B19 IgM. In 11sera anti-B19 IgM was detected, but no clinical picture was associated with these seroconversions. Viral B19 DNA was detected by Southern blot and DNA hybridisation in an amniotic sample from a case of hydrops fetalis with fetal loss. Chronic haemolytic anaemias are rare in Germany, so aplastic crisis following B19 infection1 is not the main complication in this country. The most important clinical manifestation of B 19 seems to be erythema, which was classified as either erythema infectiosum or atypical erythema. So far, no seasonal peak has been observed,2 except for epidemic outbreaks in institutions such as kindergartens or schools. However, the very different clinical manifestations of this infection make it necessary to include B 19 infection in the differential diagnosis of other viral diseases. cases
52 anti-B19
Fig 2-Monthly incidence of
B19 infections.
been recorded for school outbreaks of erythema infectiosum.5 Sporadic cases outside schools constitute the majority of infections reported here. Fig 2, however, also includes 158 cases of B19 infection diagnosed between January and June 1984 (91 in February) from an extensive outbreak in the North East of Scotland that began in a primary school .6 Our impression is of a ubiquitous infection occurring throughout 1984-86. Continued serological surveillance will be required to establish an epidemiological profile of B19 infection. Department of Medical Microbiology, University College and Middlesex School of Medicine, London WC1E 6JJ
M.
Virus Reference Laboratory, Central Public Health Laboratory, London NW9
B. J. COHEN
J. ANDERSON
Max von Pettenkofer Institute for Hygiene and Medical Microbiology, 8000 Munich 2, West Germany
TINO F. SCHWARZ MICHAEL ROGGENDORF
FRIEDRICH DEINHARDT
of parvovirus B19 in aplastic crisis T, Coccia P, Holman RC, et and erythema infectiosum (fifth disease). J Infect Dis 1986; 154: 383-93. 2. Anderson MJ, Pattison JR. The human parvovirus: Bnef review. Arch Virol 1984; 82: 137-48. 1. Chorba
al. The role
1. Anderson
MJ, Jones SE, Minson AC. Diagnosis of human parvovirus infection by dot-blot hybridisation using cloned viral DNA. J Med Virol 1985; 15: 163-72. 2. Clewley JP. Detection of human parvovirus using a molecularly cloned probe.J Med
MONTH OF BIRTH AND PREVALENCE OF MUSCULOSKELETAL DISEASES LATER IN LIFE
Virol 1985; 15: 173-81. 3. Cohen BJ, Mortimer PP, Pereira MS. Diagnostic assays with monoclonal antibodies for the human serum parvovirus-like virus (SPLV). JHyg (Camb) 1983; 91: 113-30. 4 Anderson MJ, Davis LE, Hodgson J, Jones SE, Murtaza L, Pattison JR. Occurrence of infection with a parvovirus-like agent in children with sickle cell anaemia during a two year period. J Clin Pathol 1982; 35: 744-49. 5. Cherry JD. Erythema infectiosum. In: Feigin RD, Cherry JD, eds. Textbook of pediatric infectious diseases. Philadelphia: Saunders, 1981. 6. Tuckerman JG, Brown T, Cohen BJ. Erythema infectiosum in a village primary school clinical and virological studies. J Roy Coll Gen Pract 1986; 36: 269-70.
SiR,—The influence of time of birth on events in later life is usually regarded as a matter for astrologers. However, there is evidence for influences of season of birth on height and intelligencel-5 and on the incidence of abnormalities at birth such as anencephaly, patent ductus arteriosus, and congenital dislocation of the hip.6 While working at the Nord-Norges Kurbad, a rehabilitation centre in Tromse, I noticed that the shelf length necessary to store
740 OBSERVED AND EXPECTED NUMBER OF PATIENT RECORDS IN THE
NORD-NORGES KURBAD REHABILITATION CENTRE BY MONTH OF BIRTH I
I
will be at its lowest. The patients at this centre were bom 60-70 years ago when access to fresh fruit and vegetables was probably more dependent on season than it is today. Babies bom in the summer months in those days will have been in utero at a time of relative shortage of fresh fruit and vegetables. It has been proposed that osteoarthritis is associated with abnormal stresses on the joints." If reduced sunlight during pregnancy or at weight-bearing age in small children or poor nutrition in the last two-thirds of the pregnancy causes minor axial deviations in joint movements, people born in the summer could be at greater risk of degenerative joint disease.
status
Institute of Community Medicine, University of Tromsø, N-9001 Tromsø, Norway
the medical records of patients born in the summer was twice that needed for the files on patients born in the winter (medical records are filed by birth month and day). The rehabilitation centre is only allowed to treat patients with musculoskeletal disorders; myalgia, peritendinitis, lumbago, and osteoarthritis accounted for about 60% of admissions in 19827 The catchment area is the three most northerly counties of Norway, and 99.7% of the centre’s patients live in these counties.7 Every patient has only one file, however many times he or she is admitted. From 1970 to the end of 1986 medical records were established for 8806 patients. The distribution by month of birth was compared with that expected from data on month of birth for 1981 in the three most northerly counties of Norway (supplied by Knutt Hanssen from the official population register). The table reveals a significant difference between expected and observed values (chi square 1228; DF = 11 ; p<0’001). The ratio observed/expected was highest in June and July and was lowest in December. A line joining all the monthly ratios illustrates the seasonal variation, and a test for seasonality of events with a variable population at risk8 was significant (chi-square 104-8; DF = 2; p < 0001). The peak ratio can be estimated as June 23 (mid-
summer). An association of this kind and magnitude is unexpected. Could the data be biased? For patients at this rehabilitation centre to be non-representative with regard to month of birth, would mean that patients born in the summer were more likely to go to the centre than patients born in the winter. If people born in the summer are more intelligent (as some have suggestedl3) and if referral to the hospital to some extent reflects a patient’s ability to present his or her problem adequately to the doctor, there would be possible bias. If people born in the summer are richer than people born in the winter, the same would apply, since patients have to pay part of the costs of staying at the centre. If patients bom in the winter prefer rehabilitation centres in southern Norway a difference in season of birth at a northern rehabilitation centre would be demonstrable--but I can think of no plausible mechanism for such behaviour. Might 1981 be unrepresentative of the expected distribution by month of birth for the patients (average age 65)? Data from the Central Bureau of Statistics9 show that the younger generations have more variation in the frequency of births by month than older generations, the peak being in the spring, so any bias from this source would underestimate the true difference. Is there any plausible biological explanation? Two environmental factors vary with season in this part of the world, light and nutrition. In northern Norway in midwinter the sun is below the horizon for one to two months. Markestad’O has demonstrated in Norwegian children in the Bergen area a close association between the levels of vitamin D in mothers and their newborn babies. He also showed that children from 6 to 18 months old had higher levels of vitamin D after the summer than after the winter. Some children measured in March had levels lower than what was regarded as necessary to avoid rickets. This seasonal variation in vitamin D is sunlightrelated, and would probably be even greater above the Arctic Circle. Infants in north Norway who are born in the summer will start weight-bearing in late winter and early spring when their vitamin D
I
V. FØNNEBØ
1. Mills CA. Mental and physical development as influenced by season of conception. Human Biol 1941; 13: 378-89. 2. Fitt AB. The heights and weights of men according to month of birth. Human Biol 1955; 27: 138-42 3. Chenoweth LB, Canning RG. Relation of season of birth to certain attributes of Students. Human Biol 1941; 13: 533-40. 4. Hillman RW, Slater P, Nelson MJ. Season of birth, parental age, menarcheal age and body form: Some inter-relationships in young women. Human Biol 1970; 42: 570-80. 5. Knobloch H, Pasamanick B. Seasonal variation in the births of the mentally deficient. Am J Publ Health 1958, 48: 1201-08. 6. Bailar JC, Gurian JM. Congenital malformations and season of birth Eugen Quart 1965; 12: 146-53. 7. Fønnebø V. Rehabiliteringssenteret Nord-Norges Kurbad. Tidsskr Nor Laegefor 1985; 105: 1896-98. 8. Walter SD, Elwood JM. A test for seasonality of events with a variable population at risk. Br J Prev Soc Med 1975; 29: 18-21. 9. Ekteskap, Fødsler og vandringer 1 Norge 1856-1960. Samfunnsøkonomiske Studier NR 13. Oslo: Central Bureau of Statistics, 1965. 10. Markestad T. Effect of season and vitamin D supplementation on plasma concentrations of 25-hydroxyvitamin D in Norwegian infants. Acta Paediatr Scand 1983; 72: 817-21. 11. Howell DS. Pathogenesis of osteoarthritis. Am J Med 1986; 80 (4B): 24-28.
MEASURES OF NUTRITIONAL STATUS
SiR,—The poor relation between mid-upper-arm circumference (MUAC) and weight-for-height which Mr Rees and colleagues (Jan 10, p 87) observed in north-east Brazil has also been observed amongst Khmer refugee children encamped along the Thai/ Kampuchean border.1 In the early stages of this emergency, MUAC was useful for rapid screening of children for undernutrition but was quickly replaced by nutritional assessment with weight and height data. MUAC measurement requires the minimum of equipment, and MUAC is relatively age-independent between 1 and 4 years (an important consideration in populations where accurate ages are difficult to obtain) and correlates well with muscle circumference, which is reduced in moderate to severe undemutrition. However, in Khmer children aged from 1 to 4, MUAC was only moderately correlated with weight-for-height. The correlation coefficients for each age group were similar to Philippine dataThe difference between the two indicators of leanness became more apparent when the sensitivity of MUAC in the detection of wasted children (less than 80% weight-for-height) and its specificity in rejecting non-wasted children was calculated for cut-offs of 13.5, 12-5, and 12.0 cm (table). With a cut-off of 13.5 cm, MUAC measurement can correctly classify 90% of wasted children but at the expense of including a large proportion (36%) of those not wasted. By lowering the cut-off to 12.5 cm or less, the number of non-wasted children selected is considerably reduced, but at the cost of rejecting half of those who are less than 80% weight-forheight and therefore considered to be most in need of attention. As Rees and colleagues state, which cut-off to choose will depend on local circumstances. But the Khmer study indicates that, at a cut-off of 12.5 cm or less, MUAC measurement cannot identify many more than half of those children who are wasted and even fails to identify all of the severely malnourished cases (less than 70% Relief workers should bear this in mind if MUAC alone is to be used for nutritional assessment. Because of these considerations and also because of the relatively large standard error, MUAC measurement was abandoned as the criterion for special care in favour of percentage weight-for-height. In situations that required rapid screening of large groups of
weight-for-height).
Fig 1-Clinical presentation of B19 infection.
SIR,-Dr Lefrere and Dr Courouce suggest that laboratories which diagnose human parvovirus B19 should report B19 cases, to establish an epidemiological profile. A lack of B19 antigen means that few centres can serologically diagnose B19 infection. No method for propagating this virus in cell culture has been established, and diagnostic tests for anti-B19 IgM and IgG rely on blood obtained during the viraemic phase of infection. Large-scale screening of blood donations or of people who have been in contact with B19-affected patients is still the only way to obtain sufficient antigen. We screened 160 blood units from the Munich Red Cross Blood Transfusion Service by DNA spot hybridisation with a 32P-Iabelled cloned DNA fragment of the B19 genome (PgemPTMl, kindly provided by H. Wolf, Munich), and found one positive blood unit from a symptomless donor. With this unit, an ELISA system for routine detection of anti-B19 IgM and IgG has been established. Sera (n=76) from children aged 1-15 years admitted to the paediatric unit of the University of Munich and from blood donors (n 692) aged 18-68 were tested for anti-B 19 IgM. The prevalence of anti-B19 IgG is shown in the table. =
"Other" includes abnormalliver(funcaontests,) glandular Ifever,l factor VIII treatment, intrauterine infection, and neuralgic amyotrophy.
PREVALENCE OF
ANTI-B19 IgG IN SERA OF CHILDREN (n BLOOD DONORS
In
sera
=
76) AND
(n = 692)
(n = 400) from patients with clinical indications of B 19
infection, mainly from southern Germany and Austria, between July, 1986, and February, 1987, we detected anti-B19 IgM in 52 and viral B19 DNA in one case. The clinical diagnoses of the IgM positive cases were: erythema infectiosum (15), atypical erythema (28), hydrops fetalis (2), enteritis (2), juvenile chronic polyarthritis (1), arthralgia (1), transient anaemia (1), lymphadenitis (1), and acute atypical dermatomyositis (1). An additional 300 sera from pregnant women, dialysis patients, and vaccinated medical students, examined primarily for hepatitis B markers, were tested for anti-B19 IgM. In 11sera anti-B19 IgM was detected, but no clinical picture was associated with these seroconversions. Viral B19 DNA was detected by Southern blot and DNA hybridisation in an amniotic sample from a case of hydrops fetalis with fetal loss. Chronic haemolytic anaemias are rare in Germany, so aplastic crisis following B19 infection1 is not the main complication in this country. The most important clinical manifestation of B 19 seems to be erythema, which was classified as either erythema infectiosum or atypical erythema. So far, no seasonal peak has been observed,2 except for epidemic outbreaks in institutions such as kindergartens or schools. However, the very different clinical manifestations of this infection make it necessary to include B 19 infection in the differential diagnosis of other viral diseases. cases
52 anti-B19
Fig 2-Monthly incidence of
B19 infections.
been recorded for school outbreaks of erythema infectiosum.5 Sporadic cases outside schools constitute the majority of infections reported here. Fig 2, however, also includes 158 cases of B19 infection diagnosed between January and June 1984 (91 in February) from an extensive outbreak in the North East of Scotland that began in a primary school .6 Our impression is of a ubiquitous infection occurring throughout 1984-86. Continued serological surveillance will be required to establish an epidemiological profile of B19 infection. Department of Medical Microbiology, University College and Middlesex School of Medicine, London WC1E 6JJ
M.
Virus Reference Laboratory, Central Public Health Laboratory, London NW9
B. J. COHEN
J. ANDERSON
Max von Pettenkofer Institute for Hygiene and Medical Microbiology, 8000 Munich 2, West Germany
TINO F. SCHWARZ MICHAEL ROGGENDORF
FRIEDRICH DEINHARDT
of parvovirus B19 in aplastic crisis T, Coccia P, Holman RC, et and erythema infectiosum (fifth disease). J Infect Dis 1986; 154: 383-93. 2. Anderson MJ, Pattison JR. The human parvovirus: Bnef review. Arch Virol 1984; 82: 137-48. 1. Chorba
al. The role
1. Anderson
MJ, Jones SE, Minson AC. Diagnosis of human parvovirus infection by dot-blot hybridisation using cloned viral DNA. J Med Virol 1985; 15: 163-72. 2. Clewley JP. Detection of human parvovirus using a molecularly cloned probe.J Med
MONTH OF BIRTH AND PREVALENCE OF MUSCULOSKELETAL DISEASES LATER IN LIFE
Virol 1985; 15: 173-81. 3. Cohen BJ, Mortimer PP, Pereira MS. Diagnostic assays with monoclonal antibodies for the human serum parvovirus-like virus (SPLV). JHyg (Camb) 1983; 91: 113-30. 4 Anderson MJ, Davis LE, Hodgson J, Jones SE, Murtaza L, Pattison JR. Occurrence of infection with a parvovirus-like agent in children with sickle cell anaemia during a two year period. J Clin Pathol 1982; 35: 744-49. 5. Cherry JD. Erythema infectiosum. In: Feigin RD, Cherry JD, eds. Textbook of pediatric infectious diseases. Philadelphia: Saunders, 1981. 6. Tuckerman JG, Brown T, Cohen BJ. Erythema infectiosum in a village primary school clinical and virological studies. J Roy Coll Gen Pract 1986; 36: 269-70.
SiR,—The influence of time of birth on events in later life is usually regarded as a matter for astrologers. However, there is evidence for influences of season of birth on height and intelligencel-5 and on the incidence of abnormalities at birth such as anencephaly, patent ductus arteriosus, and congenital dislocation of the hip.6 While working at the Nord-Norges Kurbad, a rehabilitation centre in Tromse, I noticed that the shelf length necessary to store
740 OBSERVED AND EXPECTED NUMBER OF PATIENT RECORDS IN THE
NORD-NORGES KURBAD REHABILITATION CENTRE BY MONTH OF BIRTH I
I
will be at its lowest. The patients at this centre were bom 60-70 years ago when access to fresh fruit and vegetables was probably more dependent on season than it is today. Babies bom in the summer months in those days will have been in utero at a time of relative shortage of fresh fruit and vegetables. It has been proposed that osteoarthritis is associated with abnormal stresses on the joints." If reduced sunlight during pregnancy or at weight-bearing age in small children or poor nutrition in the last two-thirds of the pregnancy causes minor axial deviations in joint movements, people born in the summer could be at greater risk of degenerative joint disease.
status
Institute of Community Medicine, University of Tromsø, N-9001 Tromsø, Norway
the medical records of patients born in the summer was twice that needed for the files on patients born in the winter (medical records are filed by birth month and day). The rehabilitation centre is only allowed to treat patients with musculoskeletal disorders; myalgia, peritendinitis, lumbago, and osteoarthritis accounted for about 60% of admissions in 19827 The catchment area is the three most northerly counties of Norway, and 99.7% of the centre’s patients live in these counties.7 Every patient has only one file, however many times he or she is admitted. From 1970 to the end of 1986 medical records were established for 8806 patients. The distribution by month of birth was compared with that expected from data on month of birth for 1981 in the three most northerly counties of Norway (supplied by Knutt Hanssen from the official population register). The table reveals a significant difference between expected and observed values (chi square 1228; DF = 11 ; p<0’001). The ratio observed/expected was highest in June and July and was lowest in December. A line joining all the monthly ratios illustrates the seasonal variation, and a test for seasonality of events with a variable population at risk8 was significant (chi-square 104-8; DF = 2; p < 0001). The peak ratio can be estimated as June 23 (mid-
summer). An association of this kind and magnitude is unexpected. Could the data be biased? For patients at this rehabilitation centre to be non-representative with regard to month of birth, would mean that patients born in the summer were more likely to go to the centre than patients born in the winter. If people born in the summer are more intelligent (as some have suggestedl3) and if referral to the hospital to some extent reflects a patient’s ability to present his or her problem adequately to the doctor, there would be possible bias. If people born in the summer are richer than people born in the winter, the same would apply, since patients have to pay part of the costs of staying at the centre. If patients bom in the winter prefer rehabilitation centres in southern Norway a difference in season of birth at a northern rehabilitation centre would be demonstrable--but I can think of no plausible mechanism for such behaviour. Might 1981 be unrepresentative of the expected distribution by month of birth for the patients (average age 65)? Data from the Central Bureau of Statistics9 show that the younger generations have more variation in the frequency of births by month than older generations, the peak being in the spring, so any bias from this source would underestimate the true difference. Is there any plausible biological explanation? Two environmental factors vary with season in this part of the world, light and nutrition. In northern Norway in midwinter the sun is below the horizon for one to two months. Markestad’O has demonstrated in Norwegian children in the Bergen area a close association between the levels of vitamin D in mothers and their newborn babies. He also showed that children from 6 to 18 months old had higher levels of vitamin D after the summer than after the winter. Some children measured in March had levels lower than what was regarded as necessary to avoid rickets. This seasonal variation in vitamin D is sunlightrelated, and would probably be even greater above the Arctic Circle. Infants in north Norway who are born in the summer will start weight-bearing in late winter and early spring when their vitamin D
I
V. FØNNEBØ
1. Mills CA. Mental and physical development as influenced by season of conception. Human Biol 1941; 13: 378-89. 2. Fitt AB. The heights and weights of men according to month of birth. Human Biol 1955; 27: 138-42 3. Chenoweth LB, Canning RG. Relation of season of birth to certain attributes of Students. Human Biol 1941; 13: 533-40. 4. Hillman RW, Slater P, Nelson MJ. Season of birth, parental age, menarcheal age and body form: Some inter-relationships in young women. Human Biol 1970; 42: 570-80. 5. Knobloch H, Pasamanick B. Seasonal variation in the births of the mentally deficient. Am J Publ Health 1958, 48: 1201-08. 6. Bailar JC, Gurian JM. Congenital malformations and season of birth Eugen Quart 1965; 12: 146-53. 7. Fønnebø V. Rehabiliteringssenteret Nord-Norges Kurbad. Tidsskr Nor Laegefor 1985; 105: 1896-98. 8. Walter SD, Elwood JM. A test for seasonality of events with a variable population at risk. Br J Prev Soc Med 1975; 29: 18-21. 9. Ekteskap, Fødsler og vandringer 1 Norge 1856-1960. Samfunnsøkonomiske Studier NR 13. Oslo: Central Bureau of Statistics, 1965. 10. Markestad T. Effect of season and vitamin D supplementation on plasma concentrations of 25-hydroxyvitamin D in Norwegian infants. Acta Paediatr Scand 1983; 72: 817-21. 11. Howell DS. Pathogenesis of osteoarthritis. Am J Med 1986; 80 (4B): 24-28.
MEASURES OF NUTRITIONAL STATUS
SiR,—The poor relation between mid-upper-arm circumference (MUAC) and weight-for-height which Mr Rees and colleagues (Jan 10, p 87) observed in north-east Brazil has also been observed amongst Khmer refugee children encamped along the Thai/ Kampuchean border.1 In the early stages of this emergency, MUAC was useful for rapid screening of children for undernutrition but was quickly replaced by nutritional assessment with weight and height data. MUAC measurement requires the minimum of equipment, and MUAC is relatively age-independent between 1 and 4 years (an important consideration in populations where accurate ages are difficult to obtain) and correlates well with muscle circumference, which is reduced in moderate to severe undemutrition. However, in Khmer children aged from 1 to 4, MUAC was only moderately correlated with weight-for-height. The correlation coefficients for each age group were similar to Philippine dataThe difference between the two indicators of leanness became more apparent when the sensitivity of MUAC in the detection of wasted children (less than 80% weight-for-height) and its specificity in rejecting non-wasted children was calculated for cut-offs of 13.5, 12-5, and 12.0 cm (table). With a cut-off of 13.5 cm, MUAC measurement can correctly classify 90% of wasted children but at the expense of including a large proportion (36%) of those not wasted. By lowering the cut-off to 12.5 cm or less, the number of non-wasted children selected is considerably reduced, but at the cost of rejecting half of those who are less than 80% weight-forheight and therefore considered to be most in need of attention. As Rees and colleagues state, which cut-off to choose will depend on local circumstances. But the Khmer study indicates that, at a cut-off of 12.5 cm or less, MUAC measurement cannot identify many more than half of those children who are wasted and even fails to identify all of the severely malnourished cases (less than 70% Relief workers should bear this in mind if MUAC alone is to be used for nutritional assessment. Because of these considerations and also because of the relatively large standard error, MUAC measurement was abandoned as the criterion for special care in favour of percentage weight-for-height. In situations that required rapid screening of large groups of
weight-for-height).