Pilot study

The aim of the pilot study was twofold. First, to pilot the tools whose development was described in this chapter, with the particular objectives of establishing their cultural validity and suitability for children in this context and collecting data to examine their discriminatory ability, using the measures o f item difficulty and

response distributions discussed in Chapter Eleven. Second, although long-term

studies of impairments associated with malaria suggest that speech and language deficits persist (section 2.3.3), including a previous study in this geographical area (Holding, et al., 1999), there are few such reports and none that have employed instruments of the same detail as described in this chapter. Therefore, a second aim was to conduct a preliminary investigation into the presence of persisting speech and language impairments associated with severe malaria in children.

10.4.1 Materials and methods

Children were selected from a database of patients admitted to Kilifi District Hospital (KDH) with severe malaria using the following criteria: children bom in 1990-1991, who lived in a clearly defined study area under demographic surveillance. Children who had been admitted to KDH with severe malaria were recmited to the study. Severe malaria included CM, defined as a deep level o f unconsciousness with inability to localise a painful stimulus (Blantyre coma score of <2 for 4 or more hours), a peripheral asexual parasitaemia and exclusion of other causes o f encephalopathy (Newton, et al., 2000) and severe non-cerebral malaria (‘severe non-CM’), defined as parasitaemia with prostration, multiple seizures or severe anaemia but without such a reduction in level of consciousness (Marsh, et al., 1995). Twenty-five children were identified using these criteria: 13 with CM and 12 with severe non-CM.

Twenty-seven children who had not been exposed to severe malaria were recruited from the community as a comparison group. They were the same age (8-9 years) and lived in the same villages as the children exposed to severe malaria. All children were from rural homesteads and spoke Kigiryama. The two assessors were blind to each child’s group status. Informed consent was obtained from the parent and child before the testing procedure. The location for the assessments was the child’s home, as experience in previous studies has shown that children can be reluctant to communicate when in the hospital setting. The basic format o f the session followed the main study procedure described in section 8.8. The specific order of the session was as follows: first, the child was invited to look at the picture to stimulate spontaneous speech. This was followed by conversation and storytelling with each

individual child. This section was tape-recorded for later analysis. After the

spontaneous speech session, the child was given a break. The order o f the

assessments was first the receptive language assessment, followed by the syntax assessment and finally the higher level language assessment. The candidate carried out the pragmatics observation during the play and testing sessions. Including the break, each session took about one hour.

Analysis was carried out using STATA version 6. Multiple regression was used to estimate the difference between the exposed and unexposed group scores, adjusting for age and sex.

10.4.2 Results

On discharge, eight children exposed to severe malaria were reported to have impairments, four of whom had been admitted with CM and four with severe non- CM. Two o f the cases were mute, four had limited speech and language (single words) including two with visual impairment and two had motor deficits (one of whom had disordered behaviour). Seventeen children were reported to have no neurological deficits on discharge from hospital. Twenty children were assessed 5 to 6 years after admission to KDH and five, 2 to 4 years after admission. Children exposed to severe malaria had a median age o f 8 years 8 months (range 8 years 3 months to 9 years 9 months). Twelve were female and 13 were male. The 27 comparison children had a median age of 8 years 11 months (range 7 years 8 months

to 10 years 4 months). There were 11 females and 16 males. None had been admitted

to hospital with severe malaria. All of the children were able to communicate

verbally.

Children who survived severe falciparum malaria had significantly lower scores for the receptive language, syntax and both components of the lexical semantics assessments than children unexposed to the disease (table 10.3). The exposed group’s mean scores were lower in the higher level language and pragmatics assessments but the difference was not statistically significant. Due to difficulties with sections two and three o f the assessment (section 11.2.6), only the results from section one of the pragmatics assessment are included in table 10.3. Only two children (both from the exposed group) had minor phonological problems so this was not included in the statistical analysis.

A qualitative analysis of the language samples indicated the occurrence o f word finding difficulties in 46% of the CM group, 33% o f the severe non-CM group and 7% of the unexposed group. These manifested as consistent pauses and use of fillers, paraphasias and perseveration.

Assessment (maximum score) Exposed mean (SD) n=25 Unexposed mean (SD) n=27 Est. difference exposed vs. unexposed * 95% C.I. p-value Receptive language (36) 30.88 (4.32) 33.52 (2.56) -2.35 -4.3 6 --0 .3 4 0.02 Syntax (34) 18.27 (3.83) 21.35 (3.35) -2.64 -4.91 --0 .3 7 0.02 Lexical semantics - function (n/a) 0.28 (0.09) 0.34 (0.08) -0.06 -0.11 --0.01 0.02 Lexical semantics - content (n/a) 0.54 (0.09) 0.63 (0.09) -0.08 -0.14--0.03 0.004 Higher level language (31) 14.46 (4.79) 17.24 (3.89) -2.35 -4 .8 4 -0 .1 5 0.07 Pragmatics (n/a) ** 4.03 (3.24) 3.13(3.15) 0.80 -1 .0 5 -2 .6 4 0.39

Table 10. 3: Results of speech and language assessments for exposed and unexposed groups

* Estimated differences are adjusted for age and sex ** A lower score indicates a superior performance

The distribution of scores was in general lower in children from the exposed group compared to children from the unexposed group, suggesting an overall effect rather than one or two very impaired children (see figures 11.1 to 11.6). There was no evidence that the scores of exposed children reported to have no impairments on discharge were significantly different to the scores of those discharged with impairments.

To illustrate the possible clinical significance o f these results, one child from the exposed group is described. SS was assessed 6 years after admission to KDH with CM: she had no reported neurological deficits on discharge from hospital. Her scores were two standard deviations (SD) lower than the unexposed group mean on the receptive language, syntax and higher level language assessments and on the content word component of the lexical semantics assessment. Other scores were one SD lower. During spontaneous speech, she exhibited poor turn-taking skills, word finding

difficulties and perseveration. Despite being friendly in demeanour, she dominated the conversation, showing poor listening skills, frequently made inappropriate comments and was avoided by the other children in her village. SS did not attend school, although it was not ascertained whether this was due to financial reasons or her behaviour.

10.4.3 Conclusions from the pilo t study

Children who had previously been admitted to KDH with severe malaria had, in general, significantly lower scores on the language assessments. These findings suggest that children who have had severe malaria have impairments in language functions, which persist two to 6 years after discharge. The children’s phonological systems appear unaffected: the minor phonological deficits seen in two of the children from the exposed group did not impair intelligibility. Alternatively, moderate or severe phonological impairments may have occurred in the immediate post-onset period and resolved by the time of assessment.

The improvement in the six children with speech and language problems on discharge implies that initial deficits may improve beyond the stage of mutism or severe aphasia but do not completely resolve by 6 years post-onset. Indeed, the pattern of scores indicates that basic language functions are still affected years after the malarial episode. If the deficits in these children have any parallels with those of children with acquired childhood aphasia (ACA) as a result of other aetiologies, this would suggest that many o f the cases had not reached the final stage of recovery, usually characterised by high level deficits (Lees and Neville, 1990). As all of these children had passed the first 2 years post-insult, it may be postulated that they will never fully recover their language functions. As highlighted in section 3.5, other infectious disease aetiologies are associated with a poor prognosis (Loonen and van Dongen, 1991; Paquier and Van Dongen, 1993), although the pathophysiology is different to malaria.

Although the numbers are small, the finding that children discharged with impairments achieve scores that are not significantly different to children discharged without impairments indicates that this assessment battery is more sensitive to neuro-

cognitive impairment associated with severe malaria than the neurological assessment performed on hospital discharge. This also suggests that language deficits may be an important but under-reported sequela of severe malaria.

A striking observation, possibly due to the small numbers, was that there was no difference between the scores of children who had suffered CM and those who had

severe non-CM. The prevalence of acquired neurological impairment following

severe non-CM has not previously been investigated but it is possible that certain manifestations of severe malaria other than CM may also be associated with impairments. This represents one of the central issues of this thesis and will be discussed further in the presentation of the main study results (Chapters Twelve to Sixteen).

10.5 Summary

This chapter has outlined the development of the speech and language assessment battery, the initial stages of instrument validation and piloting. A two-stage procedure was described for the development and adaptation of assessment tools using the principles of content validation. Six speech and language assessments were developed using these principles, two adapted from tasks previously used in Kilifi and the remainder based on tests or procedures in common use in the UK. The chapter concluded with a presentation of the pilot study methodology and results, suggesting that deficits in speech and language may persist for up to 6 years post-malaria and that impairments may be associated with manifestations o f severe malaria other than CM. Alterations to the battery following these results will be presented in the next chapter.