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a Departments of Pediatrics
b Psychiatry and Neurosciences
d School of Nursing, McMaster University, Hamilton, Ontario, Canada
c Departments of Epidemiology, Pediatrics, and Human Development
f Economics, Michigan State University, East Lansing, Michigan
e Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| ABSTRACT |
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METHODS. A longitudinal study was conducted of a population-based cohort of 166 extremely low birth weight survivors (501–1000 g birth weight; 1977–1982 births) and a group of 145 sociodemographically comparable normal birth weight individuals. Current health status, history of illnesses, hospitalizations, use of health resources, and physical self-efficacy were assessed through questionnaires that were administered to the young adults by masked interviewers.
RESULTS. Individuals completed the assessments at a mean age of 23 years. Neurosensory impairments were identified in 27% of extremely low birth weight and 2% of normal birth weight individuals. No differences were reported in the current health status for physical or mental summary scores. Extremely low birth weight young adults reported a higher prevalence of chronic health conditions in the past 6 months. A significantly higher proportion of extremely low birth weight individuals had functional limitations in seeing, hearing, and dexterity and experienced clumsiness and learning difficulties. Except for prescription glasses, medications for depression, and home-care services for extremely low birth weight individuals, there were no significant differences between groups in use of health care resources. Extremely low birth weight individuals had significantly weaker hand grip strength and lower scores for physical self-efficacy, perceived physical ability, and physical self-confidence.
CONCLUSIONS. Extremely low birth weight young adults seem to enjoy similar current health status to their normal birth weight peers. However, they continue to have significantly poorer physical abilities and a higher prevalence of chronic health conditions and functional limitations. Contrary to expectations, they do not pose a significant burden to the health care system at young adulthood.
Key Words: health chronic conditions functional limitations health care use physical abilities
Abbreviations: VLBW—very low birth weight ELBW—extremely low birth weight NBW—normal birth weight YA—young adult NSI—neurosensory impairments OR—odds ratio CI—confidence interval
Recent reports on the long-term outcomes of very low birth weight (VLBW) and extremely low birth weight (ELBW) infants who were born in the early post–neonatal intensive care era have moved beyond midchildhood and adolescence into young adulthood. At adolescence, most reports indicate that substantial morbidity persists in intellectual status, school achievements,1–3 behavioral difficulties,4 and lower growth attainment compared with the normal birth weight (NBW) group.5–7 Although there is some reduction in acute health care problems, the VLBW individuals have significantly higher rates of functional limitations, greater compensatory dependence, and increased use of health care resources.8,9
In the few studies that have pursued additional follow-up, many of the educational and growth disadvantages that are associated with being of ELBW and VLBW have persisted to adulthood.10–16 However, little is known of the functional limitations, health status, and health care needs of these vulnerable young adults (YAs) once they are too old to use pediatric services. Such information is necessary to project and plan for medical services beyond those that routinely are required by the general population at adulthood and middle age.
In this report, we present data at young adulthood on the general health, physical abilities, functional limitations, and health care use of a regional cohort of former ELBW infants who have been followed longitudinally from birth17 in comparison with a term-born NBW group.18 We hypothesized that although ELBW YAs would continue to have more chronic health problems, greater functional limitations, and poorer physical abilities than NBW YAs, there would be no differences in their current health status; furthermore, the absolute rates of use of health care services would decline even further than previously reported at adolescence.6
| METHODS |
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At 8 years of age, term-born children (1977–1981 births) who were comparable in gender, age, and social class19 to the ELBW group were randomly recruited from a list that was provided by the local school boards and followed longitudinally.18
Interview Protocol
The YAs were the primary respondents for all questionnaires and were interviewed by lay professional interviewers who were unaware of the group status. The interview process involved a structured format using scripted questions with a skip pattern that was administered in the same order. The majority (93%) of interviews were conducted at McMaster Children's Hospital (Hamilton, Ontario, Canada) between January 1, 2002, and April 30, 2004. Information regarding health status and health care use of YAs with severe impairment was obtained from their parents.
Questionnaires
Ethics approval was obtained from the Research Ethics Board of Hamilton Health Sciences, and written informed consent was obtained from all YAs and their parents.
Demographics
Age, marital status, current living arrangements, household membership, educational attainment and employment were obtained from the YAs by direct interview. Parents provided information on their own education and current employment. Both maternal and paternal variables were included to assign parental socioeconomic status.19
General Health Information
The following standardized questionnaires were used:
Physical Self-Efficacy Scale
The Physical Self-Efficacy Scale25 is a self-administered questionnaire that provides information on total physical self-efficacy, perceived physical ability, and physical self-presentation confidence.
Hand-Grip Strength
Hand-grip strength was measured independently in both hands using a dynamometer. Data are presented for dominant hand for participants without neurosensory impairments (NSI).
Use of Health Care Resources
The questionnaire was based on several sources.26,27 The information included visits to all health professionals, outpatient tests, and use of home-care services in the past 6 months and hospitalizations and surgery in the past 12 months. All medications that were taken on a regular basis (and reasons for taking) were noted. Use of mechanical aids or assistive devices and home/car/house adaptations, etc, were also recorded.
Statistical Analyses
2 tests of significance were used to test differences in categorical variables between groups (ELBW versus NBW) and gender-specific differences. Fisher's exact test was used when necessary. For variables with significant differences, analysis of variance to compare mean differences between groups and odds ratios (ORs) and 95% confidence intervals (CI) were calculated. T tests were used to compare mean values. Although exact P values are provided where applicable, because of multiple testing, Holm's correction28 was applied to all P < .05 separately for each table (for total group and by gender) to establish statistical significance. Values that were found to be significant by Holm's correction are indicated with a superscript Holm's beside the P values. SPSS11.0 (SPSS, Chicago, IL) was used for all statistical analyses.
| RESULTS |
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NBW Participants
Of the 145 term control subjects,18 5 were lost to follow-up, 7 refused (none had NSI), and the remaining 133 (92%) participated.
Birth Characteristics and Sociodemographics of Parents and YAs
Mean birth weight for the ELBW cohort was 841 g (SD: 124 g), and mean gestational age was 27.1 (SD: 2.3) weeks (Table 1). More than one quarter of ELBW individuals were <750 g (27%), 22% were <26 weeks, and 24% were small for gestational age.29 Mean duration of hospitalization was 101 (SD: 32) days. Both cohorts predominantly were white (>94%) and from 2-parent families (>79%), and approximately half were from the upper 2 socioeconomic levels.19 Highest educational achievement did not differ between cohorts. Mean age at assessment was 23.3 years (SD: 1.2 years) for ELBW and 23.6 years (SD: 1.1 years) for NBW (P = .02).
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2) impairments (10% vs 0%; P = .0004Holm's; Table 3). Differences in chronic physical conditions (ELBW versus NBW) were present for the following: seizures (8% vs 2%; OR: 3.8; 95% CI: 1.0–13.7; P = .03), asthma (male individuals only; 18% vs 3%; OR: 6.3; 95% CI: 1.3–29.5; P = .009), and recurrent bronchitis (6% vs 1%; OR: 8.5; 95% CI: 1.0–67.9; P = .02). The proportion of ELBW individuals with asthma by group and gender is higher than the Canadian data23 (see Table 3, footnote i). There were no differences in emotional problems and mental illness between groups.
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3 problems (P = .01). Similar differences were seen in male individuals (P < .001Holm's) but not in female individuals (P = .89). However, when participants with NSI were excluded, these differences no longer were significant for the overall group or for female individuals, but differences among male individuals remained significant (P = .001). Among those who had at least 1 chronic condition, the mean number per individual was 2.8 (SD: 1.9) for ELBW versus 2.2 (SD: 0.14) for NBW (P = .01).
Injuries
Self-report of injuries in the past 12 months, serious enough to limit normal activities, did not differ between groups (ELBW 24% vs NBW 22%; P = .71). However, both groups reported slightly higher rates than the general Canadian population (18%, aged 20–24).23
Late Retinal Detachment
In eliciting details of types of surgeries, we unexpectedly found that 6 ELBW YAs (4%) experienced sudden late retinal detachment, with 2 YAs remaining blind in the affected eye after laser surgery. Voluntary ophthalmologic assessments on 45 ELBW YAs yielded 3 additional cases of retinal tears that also required surgery. None of the NBW YAs experienced the same.
Current Functional Limitations
ELBW YAs reported significantly more functional limitations than NBW YAs by group and by gender for the following variables (Table 4): difficulty seeing (group P < .001Holm's, male P = .002Holm's, female P < .001Holm's), bilateral blindness (group P = .001Holm's, female P = .01), clumsiness (group P = .001Holm's; male P = .007, female P = .02), dexterity (P = .002Holm's; male P = .02, female P = .02), and learning disabilities (group P < .001Holm's, male P = .003, female P < .001Holm's). In addition, there were differences by group (P = .04) but not by gender for hearing difficulties and reduced self-care abilities (P = .03). These results include 7 parental proxy responses.
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3, ELBW individuals were less likely to have no limitations and more likely to have multiple limitations. These differences were significant by group (P < .001Holm's) and by gender (P < .001Holm's) and remained significant when NSI were excluded. More ELBW than NBW YAs reported limitations in carrying out "normal daily activities" as a result of health problems (21% vs 11%; OR: 2.1; 95% CI: 1.0–4.0; P = .03, NS by gender; corresponding Canadian data 19.1%23). These differences became NS when individuals with NSI were excluded. Among those with limitations, there were significant differences between groups in the reasons for limitations (P = .00004, data not shown): a significant majority (81%) of ELBW individuals cited mental illness and NSI as the main reasons, whereas a similar proportion (80%) of NBW individuals identified chronic conditions and acute injuries.
There were no significant differences by group (ELBW versus NBW: 24% vs 19%) or by gender (male: 16% vs 13%; female: 30% vs 23%) in the proportion with any absenteeism from school/work as a result of illness during the previous month. The proportions with absenteeism are similar to the Canadian data (male: 14.7%; female: 22.2%; total: 18.3%).23 However, significant differences were noted for mean number of days absent among female individuals (ELBW: 5.5 days [SD: 6.3 days]; NBW: 2.6 days [SD: 2.2 days]; P = .04, data not shown).
Health Care Use
There were no significant differences by group or by gender for the proportion with overnight hospitalizations or surgery in the past 12 months (Table 5). During the past 6 months, there were no differences in the proportion with visits to the emergency department or visits to any health professionals by group or by gender, with the exception of social worker contacts by ELBW female individuals (13% vs 4%; P = .04). The proportion who had outpatient investigations did not differ by group or by gender.
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Although a minority of individuals required home-care services, there were significant differences between groups (8% vs 2%; OR: 5.7; 95% CI: 1.2–26.1; P = .01). Significantly more ELBW than NBW YAs received services such as household help, specialized companionship, and personal care (7% vs 1%; OR: 9.5; 95% CI: 2.0–39.5; P = .009). One ELBW female individual with severe impairment required episodic respite care, and another ELBW female individual was in permanent foster care.
Physical Self-Efficacy, Physical Activity, and Hand-Grip Strength
ELBW YAs had significantly lower total scores in the physical self-efficacy scale (P < .001Holm's) and in the 2 subscales of perceived physical ability (P < .001Holm's) by group and by gender and in physical self-presentation confidence by group (P = .001Holm's) and by female gender (P = .002Holm's; Table 6). These differences persisted even when individuals with NSI were excluded.
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Despite exclusion of those with NSI, ELBW YAs had significantly lower hand-grip strength in their dominant hand compared with NBW YAs (32 [SD: 10] vs 38 [SD: 10]; P < .001Holm's) and by gender (male P = .002Holm's; female P < .001Holm's). The analysis of variance was significant for group (P < .001) and gender (P < .001), but there was no interaction.
| DISCUSSION |
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Cooke et al13 found no significant differences in health status between mainstream 20-year-old British VLBW and NBW YAs, except for lower physical functioning score (SF-36) and lower general health perception by male VLBW YAs. Unfortunately, the response rate in this study was only 50%. Hack et al11 reported higher rates of chronic health conditions (33% vs 21%) and multiple conditions among Cleveland VLBW versus NBW YAs. However, with the exception of those with NSI, the health status of VLBW YAs was equivalent to that of NBW control subjects. Similar findings were reported by Ericson and Källen10 in VLBW male individuals. A few studies reported higher rates of asthma and use of inhalers13,30 and some residual effects on respiratory function.30,31
Remarkably, we found no differences in use of health care resources at young adulthood, in terms of acute illnesses, hospitalizations, surgical procedures, and visits to specialists. There also were no differences in the use of rehabilitative services, such as occupational therapists, physiotherapists, and speech pathologists. Use of prescription medications was similar in both groups, except for medications for depression. Assistive devices such as wheelchairs were limited to those with NSI, and a similar proportion of both cohorts used braces and crutches, usually for acute injuries in the case of NBW YAs. A minority of ELBW YAs required home-care services for personal care and household help, foster care, and temporary respite care.
The most frequent compensatory aid that was used by ELBW was prescription glasses. The high prevalence of visual problems at young adulthood also was reported by Hack et al11 and Ericson.10 However, of particular concern in our study were the high rates of late retinal detachment (4%), which seem to have occurred in our study participants (born before the cryotherapy era), since the last assessment at adolescence. The discovery of 3 additional individuals with asymptomatic retinal tears among 45 YAs who volunteered to be tested lead us to believe that there may be other undetected cases. Similarly, the 15-year outcome study of the Cryotherapy for Retinopathy of Prematurity trial for threshold retinopathy32 found retinal detachment in 4.5% of treated eyes and 7.7% of control eyes. What is worrisome is that these events occurred in eyes that were judged to be normal at the 10-year assessment. The development of these adverse outcomes indicates the need for lifelong follow-up of people with a history of retinopathy.32
There are no available reports in the literature for comparison with our study regarding use of health care resources by ELBW individuals at young adulthood. Direct comparison with our same cohort at adolescence6 was not possible because the respondents in the last study were parents and the time frame was in the past 2 years. The respondents this time were the YAs, and for reasons of recall bias, the period of inquiry was only for the last 6 to 12 months. We are aware of differences in perceptions regarding health conditions between parents and children,4,9,33 but whether there also are differences in responses related to health care use is not known. It is possible that the lack of significant differences in this study may be a reflection of the overall low base rates of health care use at this age. It is clear that the costs to the health care system and other services that are associated with extreme prematurity are substantial in the early years and persist into midchildhood.34,35 Thereafter, we have shown that there is a significant decline in use of health services around adolescence6 and beyond. Contrary to the earlier pessimistic projections,36 ELBW YAs do not pose a considerable lifelong burden to the health care system. Economic evaluation is in progress.
Consistent with this study, several investigators9–11 reported that VLBW adolescents and YAs lead a less active physical lifestyle and have limited participation in sports and strenuous activities. A reduction in muscle strength and physical working capacity among VLBW boys was reported by Ericson et al.10 Rogers et al37 found that 17-year-old unimpaired ELBW survivors had significantly lower motor performance than control subjects in aerobic capacity, strength, endurance, flexibility, and activity level. They speculated whether the lower scores on these measures were a result of extreme prematurity (subclinical pulmonary compromise or subtle neuromotor difficulties) or possible sheltering by parents38 or reflected a preference by the ELBW individuals for a lower physically active lifestyle. However, we and others have reported that ELBW children are consistently described by their parents as having problems with clumsiness and coordination,6,37,39 which also were acknowledged by the ELBW YAs themselves in this study. In addition, they rated themselves lower in perceived physical ability and physical self-presentation confidence and were found to have lower hand-grip strength. Overall, a lower proportion of ELBW YAs participated in regular physical activities in comparison with NBW YAs and the Canadian national norms.22
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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We thank the ELBW and NBW YAs and their parents for cooperation with our many studies. We also thank our research staff Liz Merz (for tracing the participants), Lorraine Hoult and Mary Lou Schmuck (for statistical analysis), and Diane Turcotte (for typing the manuscript). We appreciate the support of the department of Pediatrics and the Children's Hospital, McMaster University (Hamilton, ON, Canada).
| FOOTNOTES |
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Address correspondence to Saroj Saigal, MD, McMaster University, Department of Pediatrics, 1200 Main St W, Room 4G40, Hamilton, Ontario, Canada L8N 3Z5. E-mail: saigal{at}mcmaster.ca
The authors have indicated they have no financial relationships relevant to this article to disclose.
| REFERENCES |
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800 g) survivors at 17 years of age compared with term-born control subjects.
Pediatrics. 2005;116(1)
. Available at: www.pediatrics.org/cgi/content/full/116/1/e58
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