Análisis de casos prácticos

Several studies have examined the effect o f psychosocial stimulation with or without supplementation on the development o f undemourished children. These studies are reviewed in this section and are summarized in Table 1.2.

In the Bogota study discussed earlier, two o f the six groups were randomised to receive a matemal education intervention. One group received matemal education alone and another received the matemal education in addition to supplementation from pregnancy through to age 3 (Waber et al, 1981). The matemal education component involved home visits by primary school teachers twice per week from birth to age 3. At age 3, matemal education benefited only the hearing and speech subscale o f the Griffiths test. There was no significant interaction between supplementation and education but there was an interaction between education and child age - the effect o f matemal education declining with age. Infants in the education group also performed significantly better on a Piagetian style test at 4 and 6 months but not later and there was a significant interaction between supplementation and stimulation at this age.

In a follow up at age 6-7 years there were no sustained benefits o f matemal education, although there was a hint of benefit to reading readiness for boys only (p < .07) (Super & Herrera, 1991). However, the follow up is reported in an abstract only and hence no details are available to evaluate the study.

Matemal education produced no concurrent gains on child nutritional status but at age 6 a significant benefit was found for linear growth (Super et al, 1990). The authors suggested that mothers receiving the home visiting intervention may have adopted better feeding practices resulting in improved nutritional status o f the children.

In a study in Cali, Columbia (McKay et al, 1978), 301 undemourished 3 year old children were stratified by neighbourhood and the neighbourhoods randomly assigned to one o f five treatments. Treatment involved from one to four 9 month interventions o f a combined health, nutrition and stimulation intervention at a day care centre and one group which received health and nutrition only prior to one 9 month combined intervention. This latter group performed no better at age 7 than the group receiving one

period o f combined treatment indicating that supplementation alone did not measurably benefit the children’s development. At age 7 years, the combined intervention improved general cognitive ability in proportion to the number of treatment periods received (Figure 1.3.). Children receiving treatment also performed better than a group of adequately nourished children from the same neighbourhoods but performed worse than children from high SES backgrounds. At follow up, one and two years after the end of the intervention, the IQ of the children was also directly related to the duration of intervention.

Figure 1.2. Dose -Response Effect on Child Cognition of a Combined Health, Nutrition and Stimulation Intervention in Cali, Columbia

IQ

I IS: m iddle c la ss TO; 0 treatm ent T 1: 1 treatm ent period T2: 2 treatm ent p eriods T 3: 3 treatm ent p eriods T4: 4 treatm ent periods McKay et al, 1978

Height and weight gain were also directly related to the duration of the intervention throughout the study period although at follow up three years later, when the children were 10 years old, no benefits of intervention on growth were evident (Perez-Escamilla & Pollitt, 1995).

The only intervention specifically targeting stunted children was conducted in Jamaica (Grantham-McGregor et al, 1991). 129 moderately or severely stunted children aged 9 - 24 months were randomly assigned to one of four treatment groups - stimulation.

supplementation, supplementation and stimulation or control. An additional group o f 32 non-stunted children, matched for age and sex with the control group, were enrolled as a comparison group. The intervention lasted for 2 years. Supplementation was provided for the whole family on a weekly basis and stimulation involved weekly home visits from a trained paraprofessional.

Over the two years o f intervention, stimulation benefited DQ and all the subscales while supplementation benefited DQ and the performance and locomotor subscale. Supplementation and stimulation combined had an additive rather than interactive effect and the children receiving the combined intervention caught up with the non-stunted children by the end o f the intervention period (Figure 1.4.).

Figure 1.3. Developmental Quotients of Stunted Jamaican Children from Baseline to 24 Months by Intervention Status

110 105 N o n -s tu n te d B oth S tim u la te d S u p p le m e n te d C o n tro l mo 10 mo 24 mo G r a n th a m -M c G r e g o r e t al, 1991

Child behaviour was assessed through home observations at baseline and after 6 months of intervention and no benefits o f supplementation or stimulation were found on measures o f activity, affect and the quality and quantity o f exploration (Meeks-Gardner et al, 1995; 1999). Supplementation benefited height and weight with younger children benefiting the most. No effects o f stimulation on child nutritional status were found (Walker et al, 1991).

At age 7-8 years, children were evaluated on a battery o f tests assessing cognitive function, fine motor skills and school achievement. Factor analysis o f the scores from these tests resulted in three factors: general cognitive function, perceptual motor skills and memory. The groups receiving supplementation and/or stimulation performed significantly better than the control group on more of the developmental tests than expected by chance although differences for the individual tests were not significant (Grantham-McGregor et al, 1997). There was also an interaction between matemal PPVT and supplementation on the factor representing general cognitive function indicating that supplementation was particularly beneficial for children whose mothers had a higher verbal IQ. There was also a main effect o f stimulation on a factor score representing perceptual motor skills.

There was no effect o f stimulation or supplementation on child nutritional status at this time point (Walker et al, 1996).

A further follow up at 11-12 years (Walker et al, 2000; Chang et al, in press) showed no lasting benefit o f supplementation although the group receiving stimulation and the combined intervention group had significantly better scores on the Ravens matrices, vocabulary and the WISC-R full scale and verbal scale than the controls. Intervention had no significant benefits to school achievement or child behaviour as assessed through parent and teacher ratings.

An intervention study involving stimulation, this time with severely malnourished children was also conducted in Jamaica (Grantham-McGregor et al, 1987). 16 severely malnourished children were played with daily while in hospital and this was followed by weekly home visits for 2 years and fortnightly visits for a further 1 year. The development o f these children was compared with that o f 18 severely malnourished children enrolled a year previously who received no stimulation and a group o f 21 adequately nourished children in hospital for other reasons. The children in the intervention group had higher scores on the Griffiths test up to 60 months and higher IQ scores at age 60 & 70 months than children in the control group and 2 years after leaving hospital their development caught up with that o f the adequately nourished group.

The behaviour of the children was also assessed in a laboratory setting at the end of the 3 year intervention period and the non-intervened malnourished group stayed closer to their mother and stopped play sooner than the other two groups (Grantham-McGregor et al, 1989b). The intervened malnourished group behaved similarly to the adequately nourished group. It was hypothesised that the less appropriate play behaviour displayed by the non-intervened group contributed to the continuation of their developmental deficits. The children were followed up from 7 and 14 years after leaving hospital (Grantham-McGregor et al, 1994). After controlling for current height, SES and child age, children in the intervention group scored significantly higher on the WISC full scale and verbal subscale than the control children.

Figure 1.4. Developmental Levels of Severely M alnourished Jam aican Children until Adolescence DQ/IQ z-scores Adequately nourished Mai. intervened Mai. Non-intervened Adm .1 2 4 6 8 10 12 14

Years from hospital

Grantham-McGregor et al, 1994

There were no significant differences between the groups on the performance subscale and PPVT. Differences in school achievement between the groups were not significant after controlling for SES, sex and age. There were also no differences between the intervened and non-intervened groups in anthropometry at any time.

Conclusion o f Studies Involving Psychosocial Stimulation

Remedial studies with undernourished children involving stimulation (with or without supplementation) have had more success than the nutritional supplementation programmes in improving child cognition with three out o f four o f them producing concurrent and long-term benefits for children (Grantham-McGregor et al, 1987; Grantham-McGregor et al, 1991, 1997; Walker et al, 2000; McKay et al, 1978). The study in Bogota (Waber et al, 1981) showed very limited concurrent benefits of stimulation and as no details o f the education intervention have been published it is difficult to ascertain if this is due to poor quality of this aspect o f the intervention. Two studies reported benefits to child behaviour from a program o f psychosocial stimulation (Grantham-McGregor et al, 199b; Mora et al, 1979), while one reported no benefits (Meeks-Gardner et al, 1999) although the observations were conducted after only 6 months o f intervention and it may be that a longer period o f intervention would be required to produce an effect.

1,3.5. Summary of Intervention Programs with Undernourished Children

In conclusion, nutritional supplementation programmes for infants and young children do have the potential to reduce developmental deficits and there is some evidence to suggest that supplementation is most effective if begun before the child is 24 months old. However, for greatest effect these programmes should be combined with early stimulation programmes which assist parents and health providers to promote child development through developmentally appropriate activities.

Table 1.2. Remedial interventions with undernourished children involving nutritional supplementation and/or stimulation in developing countries

Study Design Intervention Concurrent Effects Long-term Effects

Jamaica Grantham- McGregor et al, 1991, 1997 Walker et al, 1991, 1996, 2000 Chang et al (in press) 129 stunted children age 9-24 mths randomised to 4 groups for 24 mths: 1. supplementation 2. stimulation 3. supplement & stimulation 4. placebo 32 non-stunted children matched for age and sex Supplementation: 1kg milk based formula/week giving 750 kcal, 20g protein daily

Placebo: home visits

only

Stimulation: Weekly

home visits from a trained

paraprofessional

Child outcomes IQ at 24 months:

Supp. benefited DQ, performance and locomotor subscales

Stim. benefited DQ and all 4 subscales Stim. and supp. had an additive effect

Behaviour:

No benefits of supp.or stim. after 6 months of intervention

Nutritional status:

Supp. benefited height and weight and there was a significant supplementation x age interaction with younger children benefiting the most.

Stim. had no effect on growth.

Maternal outcomes Behaviour:

No benefits of supp. or stim. after 6 months o f intervention

Child outcomes IQ:

At 7-8 years:

Supplementation and stimulation benefited significantly more tests than would be expected by chance but no significant differences on any one test.

Stim. also benefited perceptual motor function.

At 11-12 years:

No benefit from supp.

Stim. had benefits in reasoning (Raven’s matrices), vocabulary and IQ on the WISC-R and verbal but not performance subscale.

Schooling:

No significant benefits on school achievement & other cognitive tests.

Nutritional status:

No long-term benefits of supplementation or stimulation on growth were found at follow up Bogota, Columbia Waber et al, 1981; Super & Herrera, 1991; Super et al, 1990; Mora et al, 1979 Details provided in table 1.2.

The 2 groups reported here are E. Maternal education from birth-36 mths F. Supplementation from pregnancy to 36 months + E above. Supplement: Details provided in table 1.2. Maternal education:

Home visits twice a week from a primary school teacher

Child outcomes IQ:

Stimulation benefited hearing and speech subscale only at 36 months

Child behaviour:

Infants receiving stimulation cried less

Nutritional status:

No effect of stimulation on growth at age 3

Maternal outcomes Maternal behaviour:

Mothers in education group more attentive and responsive at 4 months_____________

Child outcomes Schooling:

VA years after intervention, stimulation had a marginally significant effect on reading readiness for boys only.

Nutritional status:

Stimulation benefited height for age at age 6.

Table 1.2. Remedial interventions with undernourished children involving nutritional supplementation and/or stimulation in developing countries

Study Design Intervention Concurrent Effects Long-term Effects

Cali, Columbia McKay et al, 1979 Perez- Escamilla & Pollitt, 1995 301 undernourished children stratified by neighbourhood areas randomised to 5 treatments beginning at different ages Treatment involved combined health, nutrition and stimulation 5 days/wk at center. T la = 75 -84 months T lb = a s T l a with prior supplementation T2 = 63 - 84 months T3 = 52 - 84 months T4 = 42 - 84 months Supplement provided at least 75% of RDA for protein and calorie + vitamins and minerals

Child outcomes

IQ:

General cognitive ability improved with treatment in a dose-response manner. Supplementation and health care alone had no significant effect

Nutritional status:

Height and weight gain also increased with treatment in a dose-response manner.

Child outcomes IQ:

IQ scores measured on the Stanford-Binet were higher with greater duration of treatment at age 8 years

Schooling:

Lower rates of school failure and higher grade level with increasing intervention up to age 10.

Nutritional status:

At age 10 years, effects of intervention on child nutritional status were no longer evident

Jamaica Grantham- McGregor et al, 1987, 1994 3 groups in hospital aged 6 - 2 4 mths. NIM: severely malnourished with standard care (n = 18) WN: matched well nourished with standard care (n = 21) 1 year later; IM: severely malnourished with stimulation (n = 16) Treatment:

Daily play in hospital & 3 years o f home visits (1/week for 2 years and 1/fortnight for 3'^'* year) No supplement after leaving hospital

Child outcomes IQ:

24 mths after leaving hospital: DQ of IM significantly better than NIM & IM group caught up to WN group.

IM significantly higher IQ than NIM, 60 & 72 mths after leaving hospital.

Behaviour:

NIM stayed closer to mother and stopped play sooner than IM and WN after 3 years of study

Maternal outcomes Behaviour:

No benefits of intervention to maternal behaviour

Child outcomes at 14 year follow-up IQ:

IM had significantly higher WlSC full scale IQ & verbal subscale but not better in the

performance subscale or PPVT than NIM

Schooling:

No significant difference between IM & NIM in school achievement

Nutritional status:

No differences between the undernourished groups on nutritional status at any time.