Health-related quality of life in Canadian adolescents and young adults: normative data using the SF-36.
Hopman, Wilma M. ; Berger, Claudie ; Joseph, Lawrence 等
The Medical Outcomes Trust 36-item health survey (SF-36) (1,2) is
widely used to assess health-related quality of life (HRQOL). However,
Canadian normative data exist only for adults over 25 years, (3) leaving
those who work with younger populations to infer either from Canadians
over age 25 or from youth norms from other countries. Neither is ideal,
as there is mounting evidence that younger respondents differ from older
age groups. (1,2,4) For example, while younger subjects may generally be
in better physical health, those under 25 are more likely than older
groups to be struggling with major decisions about relationships and
career choices, which can negatively affect HRQOL. Normative data from
the US and Sweden exist for younger age groups, (1,2,4) but the
differences between countries can affect the validity of using these
norms for Canadian research. (3,4)
HRQOL research has historically focused extensively on older adults
to the exclusion of young adults. (5) The need for normative data is
underscored by the fact that population surveys of youth generally focus
on aspects of poor health, behavioural problems or risk-taking
behaviours and do not reflect the HRQOL of the majority. (5,6) It is
important to have normative data for the appropriate age and gender
group if HRQOL is to be examined in adolescents and young adults.
Data from the Canadian Multicentre Osteoporosis Study (CaMos) were
used to develop age- and sex-standardized norms for Canadians over 25
years. (3) CaMos recently recruited a sample of young Canadians between
16 and 24 years of age. The purpose of this study was to develop
normative SF-36 data for this age group.
METHODS
CaMos is an ongoing, prospective cohort study of 9,423 randomly
selected men and women aged 25 years and older at baseline (1996/1997),
drawn from within a 50 km radius of nine Canadian cities (St.
John's, Halifax, Quebec City, Toronto, Hamilton, Kingston,
Saskatoon, Calgary and Vancouver). In 2004, the CaMos cohort was
supplemented by a sample of Canadians aged between 16 and 24 years,
using the same methodology. Detailed descriptions of these methods are
available elsewhere, (3,7) but, in brief, households within each region
were randomly selected from listed telephone numbers, and one randomly
selected household member of the appropriate age was asked to
participate. Those who agreed to participate were sent a one-page form
prior to the interview, asking them to enquire if any of their family
members had any of the conditions of particular interest to CaMos, such
as osteoporosis or history of fracture. Those who declined were asked to
complete a short questionnaire concerning age, gender, fracture history,
family history of osteoporosis, height, weight, smoking history and
activity level. Ethics approval was obtained through the review boards
of each participating centre.
Participation involved a detailed interview, including paper-based
self-administration of the SF-36. The SF-36 measures eight aspects of
HRQOL, including physical function (PF), role physical (RP), bodily pain
(BP), general health (GH), vitality (VT), social function (SF), role
emotional (RE) and mental health (MH). Scores range between 0 (poor) and
100 (best) HRQOL. A Physical Component Summary (PCS, primarily based on
the PF, RP, BP and GH domains) and Mental Component Summary (MCS,
primarily based on the VT, SF, RE and MH domains) are standardized to a
mean of 50, with a score above 50 representing better than average and
below 50 poorer than average function. (1,2) Two methods were used to
assess the differences among the groups. First, 5-point differences in
domain scores and 2-3 point differences in summary scores were
considered clinically meaningful. (1,2) In addition, the 95% confidence
intervals (CIs) of the differences were interpreted using the
methodology described by Joseph and Reinhold. (8) Comparisons that did
not meet the 5-point (domain) or 2-3 point (summary scores) level were
still noted if the lower or upper limits of the 95% CI were clinically
interesting. (8)
After direct standardization to the Canadian population (2006
Census data), a basic descriptive analysis was completed for the eight
domain and two summary scores. This included means, standard deviations
(SD), 95% CIs and percentage at floor and ceiling (proportion receiving
the minimum and maximum score, respectively). All analyses were done
using SAS version 9.1 for Windows (Cary, NC, US). Separate analyses were
completed for men and women and for two age cohorts, those between 16
and 19 years and 20 and 24 years. Participant data were also compared
with those of the refusal group to evaluate possible selection bias:
means and 95% CIs were compared for the continuous data and frequencies
for the categorical data.
RESULTS
An eligible youth resided in 4,446 of the households contacted. Of
these, 2,419 (54.4%) refused to participate, 1,026 (23.1%) completed the
brief refusal questionnaire, and 1,001 (22.5%, 474 men and 527 women)
agreed to the complete study (questionnaires, height and weight
assessment and bone mineral density measurements). For men, 243 were
16-19 years (mean 17.3, SD=1.1), and 231 were 20-24 years (mean 21.8,
SD=1.3); for women, 264 were 16-19 years (mean 17.4, SD=1.1), and 263
were 20-24 years (mean 22.0, SD=1.3).
The age- and sex-standardized scores for the eight domains and two
component summaries are presented in Tables 1 (men) and 2 (women).
Although several domains showed a ceiling effect, there did not appear
to be a floor effect. Overall, there were small differences between the
men and women, but only two exceeded the five-point difference
considered to be clinically relevant. The women aged 16-19 scored 5.6
points higher on the RP domain than the men of the same age. The men
aged 20-24 scored 7.7 points higher than the women of the same age on
BP. The 95% CIs for the differences were 1.4-9.8 and 3.9-10.9,
respectively. In both cases, the upper but not the lower CI limits are
of clinical interest, suggesting that these differences may be
meaningful. (8)
When the two age groups were combined, the men had the higher score
on 7 of 10 comparisons, although many of the differences were not large.
The largest was in the domain of BP, with a mean difference of 4.7
points. Once again, although the difference fell short of the 5 points
considered to be clinically relevant, the 95% CI of the difference
(2.3-7.1) suggests that the upper CI limit may be of clinical interest
and that the difference may be meaningful. (8)
For men, there was a relatively large difference between age groups
for the RP domain, with the younger sample scoring a mean of 4.1 points
lower than the older sample. Although the 95% CI of the difference (-0.8
to 8.9) includes the null value of zero, the upper CI limit may be of
clinical interest. (8) For domains other than RP, the younger and older
groups of men were comparable. The scores of the two age groups of women
were also comparable for most domains and both summary components.
However, the younger group had higher mean scores on both the VT (6.3
points) and RE (6.8 points) domains. The 95% CIs for these differences
were 3.6-9.0 and 1.5-12.1, respectively. In both cases, the upper but
not the lower CI limits are of clinical interest. (8)
When participant and refusal questionnaire data were compared,
there were differences in mean weight for women aged 16-19 (62.0 and
57.8 kg for participants and refusals, respectively), but height was
similar (164.0 and 164.4 cm), suggesting that participants had a
somewhat higher body mass index. These differences may, in reality, be
smaller given that the refusal questionnaire data were based on
self-reported weight (often underestimated), whereas the
participants' weight was measured. In addition, participating women
were more likely to engage in regular physical activity (64.9% versus
57.9%).
Participating men were more likely than refusals to have fractured
a bone (44.5% versus 37.5%) and to have a family history of osteoporosis
(29.0% versus 19.5%). Similarly, participating women were more likely to
have fractured a bone (31.1% versus 21.8%) and to have a family history
of osteoporosis (30.5% versus 18.7%). This may be because they were
asked to complete an information sheet regarding family medical history
before being interviewed, whereas those who only completed the refusal
questionnaire may have had less knowledge of their family history.
DISCUSSION
The HRQOL of Canadian youth is good, on average. However, both
young men and women scored somewhat better on the physically oriented
domains, such as PF and RP, than on the mentally oriented domains, such
as VT and MH. The exception is the SF domain, one of the mentally
oriented domains, which was quite high for both men and women. The
overall pattern is similar to published normative data for those aged
25-34 years, (3) although the younger men scored 2.4 points lower on the
MCS than the adjacent age group. The relatively high physically oriented
scores but somewhat lower mentally oriented scores suggest that while
these younger groups are in good physical health, they are more likely
than older groups to be struggling with major decisions about
relationships and career choices, which can negatively affect mental
aspects of HRQOL. In general, men tended to score somewhat higher than
women, and younger (15-19 years) women tended to score somewhat higher
than older (20-24 years) women.
Normative data for adolescents and young adults also exist for the
US (1,2) and Sweden. (4) Comparisons are somewhat imprecise, as the age
groups, methodology and response rates differ. For example, Sweden
assessed those aged 13-23 years, the US sample was 18-24 years, and the
CaMos sample was 16-24 years. The US sample used a combined mail survey
and telephone survey and had a response rate of 77.1%. The Swedish study
randomly assigned participants to a telephone interview or a postal
questionnaire and reported response rates of 76.7% and 63.5%,
respectively. CaMos had a response rate of 22.5%, and participants
completed the SF-36 on their own in an interview setting.
Swedish SF-36 scores for the telephone-administered and mailed
sample were combined for comparison with the CaMos and US data. For men,
Canadian and US means were all within five points of each other.
However, mean scores for the Swedish sample were considerably better
than Canadian and US scores for four domains, i.e., BP, GH, VT and SF.
In addition, Swedish scores were also more than five points higher than
the RE and MH domains of the Canadian sample. For all six domains on
which the Swedish sample outscored the Canadian sample, the Swedish mean
fell well above the 95% CI of the Canadian sample. However, the PCS and
MCS were within two points of each other for the three countries.
For women, the results were less consistent. Canadian women had
mean scores exceeding 5 points higher than the US women on the RP and SF
domains but scored more than 5 points lower on the BP domain. Swedish
means were substantially higher than US means for PF and SF. Canadian
women scored higher than the Swedish sample on RP and the MCS but scored
7.4 points lower on the BP domain, so although there were differences,
no clear pattern emerged.
A number of limitations of these data need to be considered. First,
although participants were randomly selected, not all who were invited
to do so participated, which may affect the representativeness of the
sample. In addition, the differences between participants and
non-participants as measured on the refusal questionnaire suggest that
participants had higher fracture rates, and a higher percentage had a
family history of osteoporosis. However, this may in part be explained
by the fact that the participants were asked to complete an information
sheet regarding family medical history before being interviewed.
Finally, although the 50 km radius around each CaMos centre often
included rural areas, our data do not allow us to fully differentiate
between rural and urban regions.
Nevertheless, the strengths of the study, including the random
selection of subjects invited to participate, use of a validated
questionnaire and representation from nine centres across Canada,
support our belief that the HRQOL of Canadian youth is generally good
and that these data provide good estimates of the HRQOL of Canadian
youth. The differences among age groups, gender and country underscore
the importance of taking these factors into consideration when using
normative data.
Appendix CaMos Research Group
* David Goltzman (co-principal investigator, McGill University),
Nancy Kreiger (co-principal investigator, Toronto), Alan Tenenhouse
(principal investigator emeritus, Toronto)
* CaMos Coordinating Centre, McGill University, Montreal, Quebec:
Suzette Poliquin (national coordinator), Suzanne Godmaire (research
assistant), Claudie Berger (senior study statistician), Wei Zhou (study
statistician), Lawrence Joseph (consultant statistician)
* Memorial University, St. John's, Newfoundland: Carol Joyce
(director), Christopher Kovacs (co-director), Emma Sheppard
(coordinator)
* Dalhousie University, Halifax, Nova Scotia: Susan Kirkland,
Stephanie Kaiser (co-directors), Barbara Stanfield (coordinator)
* Laval University, Quebec City, Quebec: Jacques P. Brown
(director), Louis Bessette (co-director), Marc Gendreau (coordinator)
* Queen's University, Kingston, Ontario: Tassos Anastassiades
(director), Tanveer Towheed (co-director), Barbara Matthews
(coordinator)
* University of Toronto, Toronto, Ontario: Bob Josse (director),
Sophie Jamal (co-director), Tim Murray (past director), Barbara
Gardner-Bray (coordinator)
* McMaster University, Hamilton, Ontario: Jonathan D. Adachi
(director), Alexandra Papaioannou (co-director), Laura Pickard
(coordinator)
* University of Saskatchewan, Saskatoon, Saskatchewan: Wojciech P.
Olszynski (director), K. Shawn Davison (co-director), Jola Thingvold
(coordinator)
* University of Calgary, Calgary, Alberta: David A. Hanley
(director), Jane Allan (coordinator)
* University of British Columbia, Vancouver, British Columbia:
Jerilynn C. Prior (director), Millan Patel (co-director), Yvette Vigna
(coordinator)
Received: April 7, 2009
Accepted: July 30, 2009
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Wilma M. Hopman, MA, [1,2] Claudie Berger, MSc, [3] Lawrence
Joseph, PhD, [4] Tanveer Towheed, MD, [2,5] Jerilynn C. Prior, MD, [6]
Tassos Anastassiades, MD, [5] Suzette Poliquin, MSc, [7] Wei Zhou, MSc,
[3] Jonathan D. Adachi, MD, [8] David A. Hanley, MD, [9] Emmanuel A.
Papadimitropoulos, PhD, [10] Alan Tenenhouse, MD, [11] CaMos Research
Group [12]
Author Affiliations
[1.] Clinical Research Centre, Kingston General Hospital, Kingston,
ON
[2.] Department of Community Health and Epidemiology, Queen's
University, Kingston, ON
[3.] CaMos Methods Centre, McGill University, Montreal, QC
[4.] Department of Epidemiology and Biostatistics, McGill
University, Montreal, QC
[5.] Division of Rheumatology, Department of Medicine, Queen's
University, Kingston, ON
[6.] Division of Endocrinology, Department of Medicine, University
of British Columbia, Vancouver, BC
[7.] CaMos National Coordinating Centre, McGill University,
Montreal, QC
[8.] Department of Medicine, McMaster University, Hamilton, ON
[9.] University of Calgary, Calgary, AB
[10.] Eli Lilly Canada Inc, Toronto, Canada, and University of
Toronto, Faculty of Pharmacy, Toronto, ON
[11.] Department of Medicine, McGill University, Montreal, QC
[12.] Detailed in the appendix
Correspondence: Ms. Wilma M. Hopman, Clinical Research Centre,
Kingston General Hospital, Angada 4, Room 5-426, 76 Stuart Street,
Kingston, ON K7L 2V7, Tel: 613-549-6666, ext. 4941, Fax: 613-548-2428,
E-mail: hopmanw@kgh.kari.net
Table 1. Mean Age- and Sex-standardized SF-36 Scores for
Canadian Adolescent and Young Adult Men
Age in Years Physical Role Bodily
Functioning Physical Pain
16-19, n=243
Mean score 93.8 87.9 77.3
SD * 13.4 28.8 19.4
95% CI * 92.2-95.4 84.4-91.4 74.9-79.6
% at floor 0.7 6.2 0.3
% at ceiling 63.6 79.4 26.1
20-24, n=231
Mean score 93.5 92.0 80.9
SD 13.3 25.0 19.4
95% CI 91.8-95.1 88.9-95.2 78.5-83.3
% at floor 0.2 4.0 0.5
% at ceiling 60.9 87.9 36.8
16-24, n=474
Mean score 93.6 89.9 79.1
SD 13.3 27.1 19.4
95% CI 92.5-94.8 87.6-92.3 77.4-80.8
% at floor 0.1 5.1 0.2
% at ceiling 62.3 83.6 31.4
Age in Years General Vitality Social
Health Functioning Emotional
16-19, n=243
Mean score 79.6 63.8 86.9
SD * 14.3 16.3 19.0
95% CI * 77.9-81.4 61.8-65.8 84.5-89.2
% at floor 0.3 0.1 0.1
% at ceiling 6.0 0.1 55.4
20-24, n=231
Mean score 77.7 64.2 86.1
SD 15.0 16.7 18.5
95% CI 75.8-79.6 62.1-66.3 83.8-88.4
% at floor 0.6 0.2 2.6
% at ceiling 7.8 0.2 48.9
16-24, n=474
Mean score 78.7 64.0 86.5
SD 14.7 16.5 18.7
95% CI 77.4-80.0 62.5-65.4 84.9-88.1
% at floor 0.1 0.1 0.02
% at ceiling 6.8 0.2 52.2
Age in Years Role Mental
Health
16-19, n=243
Mean score 84.5 74.1
SD * 31.0 15.7
95% CI * 80.7-88.3 72.1-76.0
% at floor 7.1 0.4
% at ceiling 74.2 3.1
20-24, n=231
Mean score 80.7 74.5
SD 34.5 17.5
95% CI 76.4-85.0 72.4-76.7
% at floor 10.8 2.5
% at ceiling 68.6 2.3
16-24, n=474
Mean score 82.7 74.3
SD 32.8 16.6
95% CI 79.8-85.5 72.9-75.7
% at floor 8.9 1.2
% at ceiling 71.5 2.7
Age in Years PCS * MCS *
16-19, n=243
Mean score 53.5 49.6
SD * 6.9 9.8
95% CI * 52.7-54.4 48.4-50.8
% at floor 0.1 0.1
% at ceiling 1.9 0.7
20-24, n=231
Mean score 54.3 48.9
SD 6.8 9.7
95% CI 53.4-55.2 47.7-50.1
% at floor 0.4 0.6
% at ceiling 0.6 0.2
16-24, n=474
Mean score 53.9 49.3
SD 6.9 9.7
95% CI 53.3-54.5 48.4-50.1
% at floor 0.02 0.02
% at ceiling 0.4 0.3
* PCS, Physical Component Summary; MCS, Mental Component
Summary; SD, standard deviation; CI, confidence interval
Table 2. Mean Age- and Sex-standardized SF-36 Scores for
Canadian Adolescent and Young Adult Women
Age in Years Physical Role Bodily
Functioning Physical Pain
16-19, n=264
Mean score 94.5 93.5 75.6
SD * 10.7 19.0 18.6
95% CI * 93.2-95.8 91.1-95.8 73.2-77.9
% at floor 0.5 2.9 0.03
% at ceiling 55.9 85.2 23.5
20-24, n=263
Mean score 93.1 92.7 73.2
SD 10.8 21.0 20.1
95% CI 91.7-94.5 90.1-95.3 70.7-75.8
% at floor 0.1 3.4 0.1
% at ceiling 50.2 86.7 22.4
16-24, n=527
Mean score 93.8 93.1 74.4
SD 10.8 20.0 19.4
95% CI 92.9-94.8 91.3-94.9 72.7-76.1
% at floor 0.2 3.2 0.03
% at ceiling 53.1 85.9 23.0
Age in Years General Vitality Social
Health Functioning Emotional
16-19, n=264
Mean score 75.3 65.6 89.1
SD * 15.2 14.9 13.8
95% CI * 73.4-77.2 63.8-67.5 87.4-90.9
% at floor 0.3 0.03 0.03
% at ceiling 3.4 0.1 51.3
20-24, n=263
Mean score 74.1 59.3 86.6
SD 15.5 16.4 17.3
95% CI 72.2-76.1 57.2-61.3 84.4-88.8
% at floor 0.1 0.04 0.4
% at ceiling 2.0 0.1 51.2
16-24, n=527
Mean score 74.7 62.5 87.9
SD 15.4 15.9 15.7
95% CI 73.3-76.1 61.0-64.9 86.5-89.3
% at floor 0.1 0.04 0.2
% at ceiling 2.7 0.1 51.3
Age in Years Role Mental
Health
16-19, n=264
Mean score 82.9 74.8
SD * 28.0 13.5
95% CI * 79.4-86.4 73.1-76.5
% at floor 4.9 0.03
% at ceiling 68.7 1.9
20-24, n=263
Mean score 76.1 72.8
SD 33.9 14.8
95% CI 71.9-80.4 71.0-74.7
% at floor 11.7 0.04
% at ceiling 62.0 0.1
16-24, n=527
Mean score 79.5 73.8
SD 31.2 14.2
95% CI 76.8-82.3 72.6-75.1
% at floor 8.3 0.04
% at ceiling 65.4 1.0
Age in Years PCS * MCS *
16-19, n=264
Mean score 53.5 49.9
SD * 5.6 7.7
95% CI * 52.7-54.2 48.9-50.9
% at floor 0.27 0.03
% at ceiling 0.16 0.1
20-24, n=263
Mean score 53.2 47.7
SD 5.8 9.9
95% CI 52.5-54.0 46.5-49.0
% at floor .1 0.4
% at ceiling 0.8 0.2
16-24, n=527
Mean score 53.3 48.8
SD 5.7 8.9
95% CI 52.8-53.8 48.0-49.6
% at floor 0.1 0.2
% at ceiling 0.4 0.1
* PCS, Physical Component Summary; MCS, Mental Component
Summary; SD, standard deviation; CI, confidence interval
