Health Related Quality of Life

Health, as formulated by the World Health Organization (WHO, 1958) is a 'state' of complete physical, mental and social well-being and not merely the absence of disease or infirmity. Health-related quality of life (HRQL) is a narrower concept that considers the net impact or consequence of a disease or impairment and implicitly reflects the personal values of the individual (Gill and Feinstein, 1994). Measurement of HRQL can be used for comparisons with different disease conditions, as well as for cost-effectiveness and cost-utility analyses.

The challenge in pediatrics is that children are constantly developing and changing; and their personal values may also evolve over time (Rosenbaum and Saigal, 1996). Traditionally, parents or caregivers have been accepted as reliable proxy respondents on behalf of younger children or those with severe disabilities. However, there is evidence that proxy responses by parents correlate poorly with the perceptions of children. Parents have more consistent agreement with children for observable functioning (physical health), than for emotional and social functioning. Overall, parents are generally more negative, and their responses may be influenced by the burden of caregiving (Eiser and Morse, 2001). Also, health professionals have limited abilities to judge patients' HRQL, and their values may differ from those of children and their parents (Saigal et al 1999). Further work is required to understand how the characteristics of patient proxy responses influence agreement. However, it is acknowledged that although children's perspectives may differ from that of parents or health professionals, they are valid, and should be accepted. There are strong arguments for obtaining HRQL perspectives from multiple respondents (Eiser and Morse, 2001). Recently a few 'generic' and 'disease-specific' HRQL instruments been developed to measure the physical, psychological and social domains of health in young children from their own perspective. To date, there are limited studies on Quality of Life (QL) in children, and even fewer in children born preterm. In this section a few such studies conducted at various ages are described.

On a preschool quality of life questionnaire (TAPQOL) (Fekkes et al., 2000) administered to parents and neonatologists in The Netherlands, 1- to 4-year-old children born before 32 weeks gestation were reported to have significantly lower HRQL than the reference group (Theunisson et al., 2001). However, the study found differences between the neonatologists' and parents' perceptions of HRQL in terms of what conditions needed treatment. A Canadian study from British Columbia (Klassen et al 2004) used both the Infant Toddler Quality of Life Questionnaire (ITQOL) (Landgraf et al 1999) and the Health Status Classification System for Preschool children (Saigal et al. 2005), and found that the 1,140 children who required NICU care at birth had poorer health status and HRQL on a range of domains compared with the findings for 393 children who had been born full term.

A series of studies on the HRQL of children born in Ontario Canada between 1977 and 1982 weighing less than 1,000 were conducted by Saigal and colleagues. In the initial study of 156 8-year-old children who weighed less than 1,000 grams at birth and 145 full term controls (Saigal et al., 1994 a), health status was determined by health professionals using a multiattribute classification system, which also provided the levels of functional limitations (Feeny et al, 1992). This descriptive information was used to map HRQL scores using a utility function formula (HUI2), based on preferences about hypothetical health states expressed by the general public (Torrance 1995). The low birth weight children had functional limitations in several attributes, and mean HRQL scores were significantly lower than in controls (Saigal et al 1994b). In a subsequent study of the same cohort (Saigal et al 1996), directly measured preferences were elicited for the first time at adolescence using the standard gamble technique. The teenagers born weighing less than 1,000 grams reported a higher frequency and more severe functional limitations in their health status in several domains as compared to full term controls. Although their overall mean HRQL scores were significantly lower, the majority of adolescents with birth weight less than 1000 grams viewed their HRQL to be similar to normal birth weight controls (71% vs 73%). Parents of both groups rated their adolescent children's HRQL higher than the children's self ratings (Saigal et al. 2000).

In a further study to determine whether the preferences of health professionals differed systematically from those of the Ontario teenagers and their parents, hypothetical health scenarios were employed, and preferences were elicited by standard gamble technique (Saigal et al. 1999). Although there was a fair degree of agreement between the groups for milder disabilities, parents and teenagers appeared to be more 'accepting' of the more severely disabling health states than health professionals. These findings have clinical implications for medical decision-making around the birth of a very preterm infant.

Other investigators have measured parental perspectives of HRQL in 244 10-year-old children who weighed less than 1,250 grams at birth. These children participated in the landmark CRYO trial for retinopathy of prematurity (ROP) (Cryo therapy for ROP cooperative group, 1988). Using the HUI2 system (Feeny et al., 1992), threshold ROP was associated with functional limitations in health and reduction in HRQL scores and, as expected, children with poorer visual outcomes had lower HRQL scores (Quinn et al., 2004). HRQL in relation to the severity of brain ultrasounds was measured in a cohort of adolescents born preterm (Feingold et al., 2002). Paradoxically, the overall self-perceived HRQL of adolescents with a higher degree of severity of intraventricular hemorrhage was better than that of adolescents with mild (i.e. grade 0 to 2) intraventricular hemorrhage.

Recently, several studies have reported the HRQL at young adulthood on infants who were born preterm. In a telephone survey, the quality of life of 85 Danish young adults born between 1971 and 1974 in Denmark with birth weights less than 1,500grams was compared with that of subjects with normal birth weights by using both objective and subjective measures (Bjer-ager et al., 1995). Although the self-reported quality of life scores for those with physical and mental handicaps were significantly lower, the scores of non-disabled subjects were comparable to those of the group with normal birth weights. In a subsequent study in Denmark, a cohort of young adults born from 1980 to 1982 with birth weights less than 1,500 grams had similar subjective quality-of-life scores but lower objective quality-of-life scores compared to the reference group (Dinesen et al 2001). Tideman and colleagues (2001) found that on the visual analogue scale, the HRQL of 19-year-olds born at less than 35 weeks gestation was similar to the HRQL of the normal birth weight group. The quality of life of a British cohort of very low birthweight young adults assessed by SF36 was found to be similar to that of normal birthweight group (Cooke 2004). Similarly, at a mean age of 23 years, Saigal and colleagues (2006) found no differences in the self-reported mean HRQL scores in the Ontario young adults weighing less than 1000 g compared to normal birthweight controls.

Although measurement of quality of life appears to be popular, a well-defined theoretical framework for the accurate assessment of the child's conceptual and developmental viewpoint is not yet available ( Jenney and Campbell, 1997). Furthermore, most of the currently available quality-of-life measures focus to a large extent on how children are functioning in different domains as determined by age-appropriate roles. Although functional measures provide considerable valuable information, they are considered to be tapping health profiles, and not the values of individual subjects (Gill and Feinstein, 1994). Such health profiles generally paint a picture more negative than that obtained when personal valuation is sought (Guyatt, 1994). However, inperson interviews are time-consuming and expensive, and impose considerable cognitive demands on respondents. Feeny et al. (2004) compared directly measured standard gamble utility scores of the Ontario cohort at adolescence with indirectly measured scores from the HUI, based on self-assessed health status but valued using community preferences. Although HUI scores matched directly measured utility scores reasonably well at the group level, at the individual level they were poor substitutes for directly measured preferences.

Finally, despite the growing literature, measurement of self-reported quality of life continues to be viewed with skepticism by the medical community and even by some parents (Hack, 1999; Harrison, 2001). Although a considerable challenges the view that the quality of life of people with disabilitie is inevitably compromised, the prevailing perception appears to be largely negative.

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