Parental reports of behavioural outcome among paediatric leukaemia survivors in Malaysia: a single institution experience

Authors


Abstract

Objectives

To determine the behavioural impact of chemotherapy in survivors of acute lymphoblastic leukaemia (ALL) treated with chemotherapy only and to identify treatment-related or sociodemography-related factors that might be associated with behavioural outcome.

Methods

We examined 57 survivors of childhood ALL, who were off treatment for at least 2 years and were in remission, aged 4–18 years, and 221 unrelated healthy controls. The Child Behaviour Checklist (CBCL) parent report was used either in English or in Bahasa Malaysia (the national language of Malaysia) to assess the behavioural outcome.

Results

Childhood ALL survivors had significantly higher scores on externalising behaviour on the CBCL parent report than did controls. Higher problem scores were found in ALL survivors with single parents on ‘total problems’ (P = 0.03) and subscales ‘withdrawn’ (P = 0.03), ‘social problems’ (P < 0.01) and ‘delinquent behaviour’ (P = 0.03) than in survivors with married parents. Significant associations were seen between a lower education level of the father and the variables representing internalising (withdrawn, anxious/depressed) and externalising (aggressive behaviour). We observed trends on higher scores in all scales in ALL survivors with single parents than in controls with single parents or with fathers with low education level, especially primary education only.

Conclusions

Malaysian childhood ALL survivors had a significantly increased risk for externalising behavioural problems, and there was a trend towards increased risk of problems in many other behavioural scales. Understanding the sociocultural dimension of patients’ health is important to be able to design the most appropriate remedy for problem behaviours detected in this multi-ethnic population.

Abstract

Objectifs

Déterminer l'impact de la chimiothérapie sur le comportement chez les survivants de la leucémie lymphoblastique aiguë (LLA) traités par la chimiothérapie seule et identifier les facteurs sociodémographiques ou liés au traitement qui pourraient être associés aux résultats comportementaux.

Méthodes

Nous avons examiné 57 survivants de LLA pédiatrique âgés de 4 à 18 ans, qui n’étaient plus sous traitement pendant au moins 2 ans et étaient en rémission et 221 témoins sains non apparentés. Le report des parents sur la liste de vérification du comportement de l'enfant (CBCL) a été utilisé soit en anglais ou en bahasa malaysia (la langue nationale de la Malaisie) pour évaluer les résultats comportementaux.

Résultats

Les survivants de LLA pédiatriques avaient des scores significativement plus élevés que les témoins pour les comportements extériorisés dans le report CBCL des parents. Des scores plus élevés de problèmes ont été trouvés chez les survivants de LLA de familles monoparentales que chez les survivants de parents mariés pour ce qui est de «problèmes totaux» (P = 0.03) et des sous-échelles: «retranchement» (P = 0.03), «problèmes sociaux» (P < 0.01) et «délinquance» (P = 0.03). Des associations significatives ont été trouvées entre un faible niveau d’éducation du père et les variables représentant l'internalisation (retranchement, anxieux/déprimé) et l'extériorisation (comportement agressif). Nous avons observé des tendances pour des scores plus élevés dans toutes les échelles chez les survivants de LLA de familles monoparentales que chez les témoins de familles monoparentales ou de pères avec un faible niveau d’éducation, en particulier avec une éducation primaire uniquement.

Conclusions

Les survivants de LLA pédiatriques malaisiens avaient un risque significativement accru d'extériorisation des problèmes comportementaux et il y avait une tendance vers un risque accru de problèmes dans de nombreuses autres échelles comportementales. La compréhension de la dimension socioculturelle de la santé des patients est importante pour permettre de concevoir la solution la plus appropriée pour les problèmes comportementaux détectés dans cette population multiethnique.

Abstract

Objetivos

Determinar el impacto que tiene la quimioterapia sobre el comportamiento en supervivientes de leucemia linfoblástica aguda (LLA) tratados solamente con quimioterapia, e identificar los factores relacionados con el tratamiento o sociodemográficos que podrían estar asociados con los resultados conductuales observados.

Métodos

Hemos examinado a 57 supervivientes de LLA infantil, con edades entre los 4–18 años, que habían recibido tratamiento durante al menos 2 años y estaban en remisión, y 221 controles sanos no relacionados. Se utilizó la versión para padres del Inventario de Conducta de Niños (CBCL), bien en Inglés o en idioma malayo, con el fin de evaluar el comportamiento.

Resultados

Los supervivientes de LLA infantil tenían puntuaciones significativamente más altas en la externalización del comportamientos en el informe paterno del CBCL que los controles. Se hallaron unos puntajes más altos para problemas en TODOS los supervivientes de LLA con un solo progenitor en ‘problemas totales’ (P = 0.03) y las subescalas ‘retraído’ (P = 0.03), ‘problemas sociales’ (P < 0.01) y ‘comportamiento delincuente’ (= 0.03) que en los supervivientes con padres casados. Se observaron asociaciones significativas entre un menor nivel de educación del padre y las variables que representan internalización (retraído, ansioso/deprimido) y externalización (comportamiento agresivo). Hemos observado tendencias a puntuaciones más altas en las escalas de los supervivientes a LLA con un solo progenitor que en los controles con un solo progenitor, o con padres con un menor nivel de educación, especialmente solo educación primaria.

Conclusiones

Los supervivientes de LLA infantil en Malasia tenían un riesgo incrementado significativo de externalizar problemas de comportamiento y había una tendencia a un riesgo incrementado de problemas en muchas otras escalas de comportamiento. Entender la dimensión socio-cultural de la salud del paciente es importante a la hora de diseñar el remedio más apropiado para los problemas de comportamiento detectados en esta población multiétnica.

Introduction

The age-standardised incidence rates of acute lymphoblastic leukaemia (ALL) in white populations of Europe, the Americas and Oceania, and also in much of eastern Asia are generally in the range of 25–40 per million and show a marked peak at age 2–3 years (Parkin et al. 1988; Howlader et al. 2013). Cure rates have improved dramatically over the last few years, with 90% of children surviving into adulthood (Pui et al. 2004; Siegel et al. 2011). Improved survival has resulted in a multitude of long-term treatment-related toxicity and functional outcome. The most common late effects reported were neurocognitive, cardiopulmonary, endocrine and musculoskeletal difficulties and secondary malignancies (National Cancer Policy Board 2003). ALL survivors are at risk for neurocognitive deficits due to the impact on the brain of both the disease (leukaencephalopathy) and the medications, especially methotrexate (Moore et al. 2008; Bhojwani et al. 2014; Kunin-Batson et al. 2014). Side effects include difficulties with attention, visual–motor function, processing speed, working memory and mathematical reasoning, which further put patients at risk for poor quality of life (Mulhern & Palmer 2003; Krull et al. 2008; Barnes & Raghubar 2014; Kunin-Batson et al. 2014). Also the diagnosis and treatment of cancer were extremely stressful experiences, which could be associated with post-traumatic stress disorder (PTSD) (Meeske et al. 2001; Wiener et al. 2006; Rourke et al. 2007). This makes it important to monitor long-term effects of treatment, as behavioural problems could arise from the side effects.

Many studies focused on examining behavioural problems in ALL survivors who received both chemotherapy and cranial irradiation, but chemotherapy alone is becoming more common as a treatment worldwide. Studies that examine the impact of chemotherapy alone on behaviour of ALL survivors are scarce. Anderson et al. (1994) found that children with ALL who received cranial irradiation showed behavioural problems, but other studies did not suggest that such children had more behavioural problems than children who did not (Mulhern et al. 1989; Sawyer et al. 1989; Noll et al. 1997). Buizer et al. (2006) reported that survivors of childhood ALL who received chemotherapy only had a moderately increased risk of behaviour and educational problems compared to children with Wilms’ tumour or a control group of healthy peers. Schultz et al. (2007) found that adolescent survivors of cancer were 1.5 times more likely than siblings to have symptoms of depression/anxiety, and 1.7 times more likely to have antisocial behaviours. The scores in the depression/anxiety, attention deficit and antisocial domains were significantly elevated in adolescents treated for leukaemia or central nervous system tumours when compared to siblings. Schultz et al. (2007) also found that treatment with cranial irradiation and/or intrathecal methotrexate (IT MTX) was a specific risk factor. Mackie et al. (2000) reported that adult survivors of childhood ALL and Wilms’ tumour have long-term effects on interpersonal functioning and coping.

Studies on behavioural problems in paediatric cancer patients in developing countries are scarce (Yeh & Wang 2004). We believe that it is necessary to perform a similar study in the developing countries, especially Malaysia, because the results of studies carried out in the developed countries might not be applicable to our survivors here. Factors such as multi-ethnicity, cultural beliefs and use of complementary or alternative medicine might contribute to different behavioural problems in our survivors. Until recently, there were very few paediatric experts treating childhood leukaemia in Malaysia, and they had to cope with limited resources. However, with improved resources and better parental understanding of the need for chemotherapy for their child's acute leukaemia, more children are receiving and completing treatment. As cure rates improve, it has become more important to assess the patient's behavioural problems. We conducted a study on behavioural outcome among our patients with the following objectives: (i) to determine the behavioural outcome in survivors of ALL treated with chemotherapy only and (ii) to evaluate factors that might be associated with behavioural outcome.

Materials and methods

This was a single-institution study. All patients were referred to the paediatric oncology centre at the National University Hospital Kuala Lumpur, Malaysia. From the database, 136 ALL survivors who fulfilled study criteria were identified. Seventy-one (52%) survivors were lost to follow-up. Those lost to follow-up may be deceased or be in continued follow-up by their primary physician who referred to us at diagnosis. Possibly they sought complementary and alternative medicine (CAM) after completing conventional treatment. CAM use is common among children with cancer in Malaysia, and CAM was primarily used to complement rather than replace conventional treatments in our patients (Hamidah et al. 2009). Another 7 patients missed clinic follow-up appointment, and they were excluded from the study. Thus 58 patients were approached for the study, and 57 consented. The 57 children were aged 4–18 years and visited the clinic between 1 December 2008 and 31 December 2009 for the study. All had been off-treatment for at least 2 years and were in remission. The control group consisted of healthy age-matched school children.

The University Institutional Review Board approved the study, which used a structured questionnaire survey form in English and Bahasa Malaysia (the national language of Malaysia). The internal validation of the questionnaire in Bahasa Malaysia, which was translated from the original English version, was between 0.7 and 0.9 (Cronbach alpha). The questionnaire was reviewed by the members of the research team for content validity and was pilot tested on 100 parents who attended the paediatric clinic follow-up. All eligible patients were approached by one investigator. Written informed consent was obtained from a parent. We hypothesised that the survivors of our ALL patients were at increased risk of behavioural problems.

Questionnaire

The Child Behaviour Checklist (CBCL) parent report is a widely used instrument that assesses social competence and behavioural problems of children 4–18 years of age (Achenbach 2001). The problem scale is comprised of 113 questions that fall into three global scales: internalising, externalising and total behaviour problems. Eight subscales were also computed: ‘withdrawn’, ‘somatic complaints’, ‘anxious/depressed’, ‘social problems’, ‘thought problems’, ‘attention problems’, ‘rule breaking behaviour’ and ‘aggressive behaviour’. Parents answered the questions based on their child's behaviour for the past 6 months. Each question was scored on a 3-point scale (0 = not true, 1 = somewhat or sometimes true, 2 = very true or often true). Raw scores were converted to T scores with a mean of 50 and a standard deviation of 10, with the norms of the developers.

Study design

We evaluated behavioural outcome of the study participants and compared the CBCL scores between the ALL survivors and controls in all three global scales and eight subscales. The association of demographic and medical variables with the CBCL scores among ALL survivors was determined. Demographic and medical variables included the patient's age at diagnosis, age at study entry, gender, ethnic, parental marital status, parental education level and occupation, monthly household income and time since diagnosis. We also compared the CBCL scores between the ALL survivors with single parents and controls with single parents. The basis of our analysis was to find the proportion of scores from our study participants that departed from the normative mean by ≥1.5 SD (within the borderline clinical range and clinical range) after adjustment for age and gender. On the CBCL, a borderline clinical range is demarcated by T scores of 65 (93rd percentile) to 69 (97th percentile) and T scores >70 (98th percentile) are in the clinical range.

Statistics

With a significance level (alpha) of 0.05, a difference in mean of 10 ± standard deviation scores in the CBCL between the study group and control group, the calculated power of this study was 86.0%. Statistical analyses were conducted using the Statistical Package for Social Studies (SPSS for Windows version 22; SPSS Inc, Chicago, IL, USA). The demographic data were analysed using t-test (quantitative data) and chi-square test (qualitative data). For the CBCL scores, t-test was used. Pearson correlation was used to determine whether there was any association between continuous variables. Any significant variables found in the earlier analysis were then included into the appropriate multivariate analysis.

Results

Participants’ characteristics

Patients were stratified into risk groups based on clinical criteria, immunophenotype, and presence or absence of extramedullary disease. Of the 57 survivors, 36 were standard-risk ALL, 16 were high-risk ALL, and 5 were relapsed ALL (being in remission after a second treatment). Patients had been treated according to the UKALL 97(99) treatment protocol and were diagnosed between January 2000 and May 2007. Relapse patients were early bone marrow relapse (n = 2), late bone marrow relapse (n = 2) and testicular relapse (n = 1). The BFM2000 relapse treatment protocol was used for the relapsed patients. Patients received CNS-directed chemotherapy as part of their treatment, consisting of intrathecal (IT) monotherapy with methotrexate (MTX) or cytarabine. None of the patients in this study received cranial irradiation.

The demographic and clinical characteristics of the survivors are shown in Table 1. Characteristics of only 34 of 71 patients who dropped out were able to be traced. Two primary schools and a secondary school in Kuala Lumpur participated in the study as controls. We distributed 500 questionnaires to school children. Questionnaires were returned by parents of 325 (65%) school children, but only 221 (44%) questionnaires were properly completed.

Table 1. Characteristics of childhood ALL survivors and controls
 ALL Survivors (n = 57)Controls (n = 221)P-value
  1. NA, not applicable; n, number; SD, standard deviation; *, analysis using t-test; other P-values, analysis using chi-square.

ChildhoodMean (SD)Mean (SD) 
Age in years at diagnosis4.80 (2.81)NANA
Age in years at study entry11 (2.87)12.25 (2.97)<0.05*
Time in years from diagnosis to study6.77 (2.39)NANA
Gendern (%)n (%) 
Female28 (49.1)118 (53.3)0.56
Male29 (50.9)103 (46.7) 
F:M ratio0.961.15 
Ethnicn (%)n (%) 
Malay41 (72.0)151 (68.3)0.44
Chinese10 (17.5)54 (24.4) 
Others6 (10.5)16 (7.3) 
Family
Marital statusn = 52, (%)n = 218, (%) 
Married46 (88.5)193 (90.6)0.64
Single parents6 (11.5)20 (9.4) 
Parents education level
Fathern = 55, (%)n = 215, (%) 
Not schooling0 (0)3 (1.4)0.68
Primary school7 (12.7)19 (8.8) 
Secondary school31 (56.4)125 (58.2) 
Tertiary17 (30.9)68 (31.6) 
Mothern = 56, (%)n = 217, (%) 
Not schooling0 (0)4 (1.8)0.73
Primary school6 (10.7)20 (9.2) 
Secondary school30 (53.6)122 (56.2) 
Tertiary20 (35.7)71 (32.8) 
Parents occupation
Fathern = 51, (%)n = 193, (%) 
Office work18 (35.3)64 (33.2)0.93
Field work19 (37.3)71 (36.8) 
Professional2 (3.9)12 (6.2) 
Others12 (23.5)46 (23.8) 
Mothern = 52, (%)n = 189, (%) 
Office work16 (30.8)91 (48.1)0.08
Field work2 (3.8)3 (1.6) 
Professional0 (0)6 (3.2) 
Housewife29 (55.8)78 (41.3) 
Others5 (9.6)11 (5.8) 
Monthly householdn = 48, (%)n = 191, (%) 
Income (MYR)
0 to 1000 (US$0-333/€0-250)15 (31.3)31 (16.2)0.13
1001 to 3000 (US$334-1000/€250-750)8 (16.7)45 (23.6) 
3001 to 5000 (US$1000.33-1666.67/€750.25-1250)12 (25.0)63 (33.0) 
5001 to 7000 (US$1667-2333.33/€1250.25-1750)4 (8.3)28 (14.7) 
7001 to 9000 (US$2334-3000/€1750.25-2250)4 (8.3)9 (4.7) 
> 9000 (US$>3000/€>2250)5 (10.4)15 (7.8) 

Child Behaviour Checklist

We found statistically significant differences in scores for externalising behaviour, former patients scoring higher than controls [t(276) = 2.1, P = 0.04)] (Table 2). We observed a trend of higher scores for total problems, internalising, ‘withdrawn’, ‘somatic complaints’, ‘social problems’ and ‘aggressive behaviour’ in ALL survivors compared to controls although this was not statistically significant (Table 2). Significant group differences were detected in total problems, and 3 of 8 subscales of the CBCL, with significantly higher problem scores for ALL survivors with single parents compared to ALL survivors with married parents: ‘total problems’ [t(50) = 2.29, P = 0.03)], ‘withdrawn’ [t(50) = 3.12, P = 0.03)], ‘social problems’ [t(50) = 3.8, P < 0.01)] and ‘delinquent behaviour’ [t(50) = 2.2, P = 0.03)] (Table 3). In this study, the single parent could be a divorced/separated or widowed mother (or rarely father). When we compared the ALL survivors with single parents against controls with single parents, we observed higher scores in all main scales and subscales in the former group which points to an important association (Table 3). The very small numbers in the group analysis most likely contributed to insignificant results, but the trend implies that the association likely becomes significant with a larger numbers of subjects. Significant associations were seen between the variables ‘internalising’ (F(2,52) = 3.4, P = 0.04), ‘withdrawn’ (F(2,52) = 3.9, P = 0.03), ‘anxious/ depressed’(F(2,52) = 6.6, P < 0.01) and ‘aggressive behaviour’(F(2,52) = 4.2, P = 0.02) and the father's level of education, with significantly higher problem scores for ALL survivors with lower education levels of the fathers (Table 3). Interestingly, we observed the highest scores in all other CBCL scales associated with fathers with primary education only. Thus, our ALL survivors whose fathers had low-level education were at increased risk of reporting behavioural problems. The number of subjects in group comparison was small in this study; thus, this interesting trend could be the subject of a larger study. There was no association between CBCL scores and age at diagnosis, age at study entry, time from diagnosis, gender, ethnicity, parents’ occupation, mothers’ education level or household income.

Table 2. Child Behaviour Checklist (CBCL) parent report scores by group
 ALL Survivors (n = 57)Controls (n = 221)P-value
Mean (SD)Mean ( SD )
  1. ALL, acute lymphoblastic leukaemia; n, number; SD, standard deviation.

Main scales
Total problems56.67 (10.34)54.65 (10.99)0.21
Internalising58.39 (10.15)56.05 (10.87)0.14
Externalising55.79 (8.48)52.72 (10.32)0.04
Subscales
Withdrawn58.28 (7.33)56.89 (7.45)0.21
Somatic complaints60.21 (9.26)58.43 (7.99)0.19
Anxious/depressed57.33 (6.51)57.40 (8.22)0.95
Social problems58.42 (6.42)57.94 (7.04)0.64
Thought problems55.81 (6.79)55.85 (7.04)0.97
Attention problems57.16 (5.88)57.71 (6.78)0.58
Delinquent behaviour54.46 (5.60)54.58 (5.49)0.88
Aggressive behaviour58.18 (7.27)56.39 (6.88)0.09
Table 3. Demographic risk factors for CBCL scoring in ALL survivors
 Parent's marital statusSingle parentsFather's education
Married (n = 46)Single (n = 6)P-valueALL Survivors (n = 6)Controls (n = 20)P-valuePrimary (n = 7)Secondary (n = 31)Tertiary (n = 17)P value
Mean (SD)Mean (SD)Median (IQR)Median (IQR)Mean (SD)Mean (SD)Mean (SD)
  1. n, number; SD, standard deviation; IQR, interquartile range.

Main scales
Total problems55.52 (10.71)65.00 (7.01)0.0363.00 (59.25, 72.75)59.50 (50.25, 66.0)0.2465.14 (6.31)55.26 (11.58)55.35 (8.25)0.06
Internalising57.28 (10.09)66.00 (10.97)0.0566.50 (56.00, 76.75)58.00 (50.0, 68.75)0.2967.57 (7.44)57.10 (10.83)57.47 (8.65)0.04
Externalising55.17 (8.26)61.50 (9.59)0.0961.00 (52.75, 71.00)55.50 (51.0, 62.50)0.2762.57 (8.60)54.87 (8.82)54.06 (6.99)0.06
Subscales
Withdrawn57.39 (6.88)65.67 (8.31)0.036.0 (2.5, 8.25)2.5 (1.0, 6.5)0.1965.29 (6.18)57.45 (7.43)57.12 (6.62)0.03
Somatic complaints59.61 (9.32)64.00 (9.82)0.253.847 (2.25, 9.25)2.0 (1.0, 5.75)0.3264.86 (10.30)60.03 (9.17)59.24 (9.26)0.39
Anxious/Depressed56.87 (6.18)61.67 (8.96)0.056.5 (3.0, 11.25)4.0 (2.0, 9.5)0.3965.14 (5.64)56.61 (6.58)55.94 (4.82)<0.01
Social problems57.26 (5.80)67.00 (6.51)<0.018.5 (4.0, 10.0)4.5 (1.25, 6.0)0.0963.57 (6.55)58.00 (6.20)57.00 (6.42)0.07
Thought problems55.57 (6.98)59.83 (6.34)0.243.0 (1.75, 5.25)2.0 (1.0, 3.75)0.2958.71 (6.87)55.77 (7.14)54.82 (6.44)0.46
Attention problems56.78 (6.02)61.83 (4.36)0.146.5 (5.0, 9.25)6.0 (3.25, 8.0)0.5361.00 (4.93)56.48 (6.05)56.53 (5.85)0.18
Delinquent behaviour54.11 (5.11)59.83 (8.21)0.034.0 (1.0, 5.75)2.0 (1.25, 4.0)0.3956.57 (7.30)54.29 (5.65)53.24 (4.62)0.42
Aggressive behaviour57.67 (7.06)62.00 (8.85)0.199.5 (5.25, 16.0)6.0 (2.25, 10.5)0.1865.14 (8.71)57.39 (6.85)56.47 (6.45)0.02

Discussion

Previous reports on behavioural problems in children with ALL mainly concerned children who were treated with cranial irradiation (Noll et al. 1997; Hill et al. 1998; Mackie et al. 2000; Zebrack et al. 2002; Yeh & Wang 2004; Schultz et al. 2007; Mody et al. 2008; Haddy et al. 2009). A study on survivors who received cranial irradiation reported problems in both internalising and externalising behaviour (Mulhern et al. 1989; Shelby et al. 1998), while another study which did not involve cranial irradiation reported some internalising and attention problems (Buizer et al. 2006). In this study, the CBCL parent-reported score indicated more problems in externalising behaviour for children with ALL compared to controls. This means our survivors could have more problems attributed to aggressive, hyperactive, non-compliant or undercontrolled behaviour. An important observation of higher scores in all main scales and some of the subscales in ALL survivors could indicate increased risk of behavioural problems unrecognised by their surroundings.

A few factors could have contributed to the findings in our study. Given that Malaysia is a multi-ethnic country, cultural differences in lifestyle may contribute to different behavioural processes and outcomes in parents’ perceptions of their children problem behaviour. The Malay ethnic usually has a strong cultural belief, and children are expected to abide by regulations and norms of their culture; any behaviour that parents think could be aggressive or disobedient might be perceived as a significant problem. Factors related to family issues such as marital problems, single-parent status, societal attitudes to illness or poor family dynamics could increase stress levels for parents. Hence, these parents may have perceived more problem behaviours in their children. Having many children or looking after grandparents in the same household could also increase the financial burden and stress to families with lower education who could have lower monthly income. Thompson et al. (2009) in a longitudinal study of 55 children with cancer reported that peer factors could influence later externalising behaviour. Survivors who were older at diagnosis were at greater risk for later externalising behaviour.

We found significantly higher problem scores attributable to ‘total problems’, ‘withdrawn’, ‘social problems’ and ‘delinquent behaviour’ in ALL survivors with single parents compared to ALL survivors with married parents. Furthermore, when we compared the ALL survivors with single parents against controls with single parents, we observed interesting trends of higher scores associated with behavioural problems in the former group. In a previous report by Mulhern et al. (1989), a twofold higher risk of having internalising symptoms was seen in children from single-parent residence. These children had a greater risk of showing fearful, inhibited or over-controlled behaviour suggesting that single parents may have more difficulty meeting their children's needs than do parents with a spouse on whom to rely, making the child more vulnerable to problems in school and other settings (Mulhern et al. 1989). However, the study did not report any control group with single parents for a better comparison. In a meta-analysis reported by Amato (2001), children with divorced parents continued to score significantly lower on measures of psychological adjustment, self-concept and social relations. Therefore, clinical or educational interventions should be considered to help to moderate the effects of divorce/separation in this group of patients.

We also found that a lower educational level (especially with primary education only) of the fathers was associated with higher parent-reported problem scores. This association has rarely been reported previously. Fathers with less education might have difficulty understanding the disease, be afraid and anxious, or lack family or other resources for coping. These factors may have resulted in fathers’ feelings of inadequacy, depression and withdrawal especially. Zebrack et al. (2002) reported that survivors of leukaemia/lymphoma with lower educational attainment had significantly more symptoms of depression and somatic distress. In addition, ‘anxious/depressed’ and ‘aggressive behaviour’ could be considered as part of the symptoms of PTSD that occurred after severe life-threatening event of been diagnosed with ALL and been experienced a stressful life during the treatment. In this study, the functional disabilities had been significantly exaggerated in situation fathers with lower education level when other environmental factors were also present. Earlier PTSD was reported significantly more often by survivors of childhood cancer who had a lower education level, lower annual income and who had been unemployed (Stuber et al. 2010). Future studies should investigate school performance, missed school time, repetition of classes and health problems affecting regular school attendance.

The present study has a few methodological limitations that should be considered when interpreting the results. First, the study participants were self-selected, and 71 of 136 survivors (52%) were lost to follow-up. We were unable to determine how the survivors who did not participate in this study differed in behavioural outcomes from those who did. We thought of few measures that could improve the follow-up rate of our survivors: (1) possibly, shared care with state paediatricians/physicians when regular follow-up of patients reaches intervals of 6–12 months or longer; (2) update survivors contact details in the medical records and database periodically; (3) telephone patients if they have difficulty coming to clinic, especially those studying in universities or working; (4) for those possibly on CAM, re-emphasise informed knowledge about CAM and the importance of remaining on allopathic follow-up for monitoring of long-term side effects.

Second, parents’ reports have weaknesses compared to adolescents’ self-reports. Concordance between patient and parent ratings was reported to be lower than between ratings given by mothers and fathers (Seiffge-Krenke & Kollmar 1998). Furthermore, mothers experiencing stress due to marital problems perceived more problem behaviour in their children. Therefore, integrating both adolescents’ self-reports and parents’ reports may be advantageous in future studies. Third, our study findings were based on a cross-sectional study. A longitudinal study involving both parents’ report and adolescents’ self-reports could reveal what changes occur over time, especially any emotional stress pattern.

Despite these limitations, we believe that this study may indicate the kinds of problems seen in similar settings in other areas in Malaysia and maybe also in other SE Asian countries which share sociodemographic factors with Malaysia. The strength of our study was that the sample was homogeneous (all ALL patients). Future studies of problem behaviour in paediatric ALL survivors could be more informative with longitudinal study and involving multiple informants (parents, teachers and medical doctors). Observation by medical personnel in long-term follow-up clinics is important and probably more accurate in their assessment with respect to individual patients. This is important for the development of appropriate and effective psychosocial support interventions tailored to individual patients. For patients in single-parent families, an appropriate support system especially psychological and emotional assistance should be made easily available and accessible to the parent from diagnosis throughout long-term follow-up. Similarly, for fathers with lower education attainment, a structured parent support organisation could help to ease the psychological burden by sharing their experiences in looking after their children with cancer and by giving advices.

Conclusions

Our study findings show that survivors of childhood ALL who received chemotherapy only at our centre reported a significantly higher incidence of externalising behavioural problems than the control group. Furthermore, they reported higher scores in other main scales and some subscales. Also survivors with single parents or lower education level of fathers were at increased risk of reporting behavioural problems.

Acknowledgement

This study was supported by a research grant from the Faculty of Medicine, National University of Malaysia.

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