Supplementary Appendix to “Comparison of Trends in U.S. Health-Related Quality of Life over the
2000’s Using the SF-6D, HALex, EQ-5D, and EQ-5D Visual Analog Scale versus a Broader Set of
Symptoms and Impairments”
This Appendix gives sample sizes and covers three issues: the distribution of scores across
measures, comparison of the health trend in MEPS data to the trend another national survey (NHIS)
using the Survey Based Symptom/Impairment measure (SSI), and alternate mapping of SF-12
questions that changed in 2003, for both the SSI and SF-6D measures.
Sample Sizes
Table 1A shows sample sizes in each year of MEPS, for those with complete health data on
all three measures available from 2000-2010, and those with complete data on measures available
from 2000-2003. While those with incomplete HRQOL data were slightly younger, male, and nonwhite, and a higher proportion were missing in 2000 than in other years, rates of missingness
differed little across years by age, gender, and race (results available from authors).
Table 1: Sample Sizes
Survey
Sample 18+
Sample age 18+
that returned
mailed health
questionnaire*
Percent of those returning health
questionnaire with complete data on:
SF-6D, SSI, and HALex
VAS
EQ-5D
2000 MEPS
17,555
15,502
90.6
86.3
96.5
2001 MEPS
23,686
20,966
96.0
95.7
97.7
2002 MEPS
27,275
24,249
96.3
95.5
98.3
2003 MEPS
23,511
20,821
97.2
95.4
98.3
2004 MEPS
23,819
20,973
95.5
2005 MEPS
23,527
20,680
95.2
2006 MEPS
23,786
20,832
95.4
2007 MEPS
21,745
19,067
95.3
2008 MEPS
23,162
20,526
95.3
2009 MEPS
25,998
23,171
95.1
2010 MEPS
23,422
20,802
95.4
*MEPS survey weights account for this non-response to the entire health questionnaire, but not for nonresponse to particular questions that prevent the calculation of summary health measures.
Distribution of Scores Across Measures
The distribution of scores on each health measure is shown in Figure 1A. While all measures
had some lumping of scores at the high end, the HALex and EQ-5D had the least variation in scores,
and the SF-6D and VAS had the widest variation. The distribution of the SSI measure was in between
that of these other measures.
.6
SSI
.8
1
.5
0
.1
.2
.3
Fraction
.2
.4
.6
SF6D
.8
1
-.5
0
.5
1
HALex
.4
.3
.2
.1
0
0
.1
.2
.3
Fraction
.4
.5
.4
.5
.2
Fraction
.4
.5
.4
0
.1
.2
.3
Fraction
.3
.2
0
.1
Fraction
.4
.5
Figure 1A: Distribution of Scores on each Health Measure in Pooled 2000-2002 MEPS Data
0
.5
EQ5D
1
0
.2
.4
.6
VAS
.8
1
2
Comparison to Trend in the National Health Interview Survey
To test for consistency in SSI scores across two different national health surveys covering the
same time period, we calculated SSI scores in both MEPS and the National Health Interview Survey
(NHIS) using the set of impairments and symptoms available in NHIS. This required omitting only the
questions on cognition, pain and energy from our original SSI scoring in MEPS. Figure 2A shows the
trend in age-adjusted HRQOL scores across these surveys from 200 through 2010. While the trends
show some small differences in variation over time, they are quite similar.
Figure 2A: Comparison of HRQOL Trends in MEPS and NHIS, Age 18+
0.90
0.88
Mean HRQOL Score
0.85
SSI in NHIS
0.83
SSI in MEPS
0.80
0.78
0.75
0.73
0.70
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
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Alternate Mappings of Changed SF-12 Items
The wording of questions for each health measure are given in Table 1A (end of Appendix).
Three of the questions used our ‘survey-based symptom and impairment’ (SSI) approach were
affected by a switch from SF-12 version 1 to version 2 in the MEPS data in 2003. In version 2, the
response choice "a good bit of the time" was dropped for questions on anxiety, depression, and
energy. In addition, the wording of the depression question was changed from “downhearted and
blue” to “downhearted and depressed”. The remainder of this appendix discusses our sensitivity
analysis on the handling of these question changes.
Alternate Mapping for the SSI Measure
In constructing the SSI measure, we examined three different adjustments for this dropping
of the “good bit” option from the questions on anxiety, depression, and energy. The first was to
hold constant these three symptoms in 2003, adjusting prior years to account for this. This yielded
scores very similar to the non-adjusted version shown in the main paper. The second was to follow
the SF6D scoring and randomly assign those who responded ‘good bit’ in version 1 to the adjacent
categories (‘most’ and ‘some’). The third was to examine the existing distribution of responses to
these categories in each year and assign those who responded ‘good bit’ to the adjacent categories
in that same proportion. For example, in 2000, 41% reported feeling calm ‘most of the time’ and
17% ‘some of the time’, indicating that only 28% of responses to these two categories were in the
‘some’ category. Thus, in years prior to 2003, we assigned 28% of those who reported ‘good bit’ on
this question to the ‘some’ category, which classified them as ‘anxious’ on our dichotomous
variable, and the remainder were assigned to the ‘most’ category, where they remained classified as
non-anxious. The same method was used to reassign pre-2003 ‘good bit’ responses to the energy
question. This method was not tested for the depression question since its wording changed in
version 2, which could affect the distribution of responses in a manner difficult to account for.
As shown by the black lines in Figures 3A and 4A, this adjustment raised anxiety rates and
reduced low energy rates rates prior to 2003. The resulting drop in anxiety and rise in low energy in
2003 appeared too dramatic. Thus, our first approach of holding these things constant in 2003
appears to be a better approximation of what happened than our attempts to redistribute scores.
The random assignment adjustment had a less dramatic effect, more similar to assuming no change
in these items in 2003. Given this similarity and the fact that it is safest to assume no change in
depressive symptoms due to the change in question wording, it is reasonable to also assume no
change for anxiety and low energy in the SSI scoring. Because the combined effect of assuming no
change in these items was almost identical to making no adjustment for the question changes, we
show the unadjusted version in the main paper.
4
Figure 3A: Prevalence of Anxious Symptoms for SSI Measure Using Alternate Mappings for these
Items to Adjust for Change to SF-6D Version 2 in 2003
Figure 4A: Prevalence of Low Energy for SSI Measure Using Alternate Mappings for these
to Adjust for Change to SF-6D Version 2 in 2003
Items
note: scores in figure not shown all the way through 2010 since focus is on period surrounding 2003 question
change.
Alternate Mappings for the SF-6D Measure
The main paper shows the standard scoring distributed by SF-6D developers for use with
each version of the SF-12. This scoring reassigns responses to role model questions from SF-12v2 to
try to match to the dichotomous response categories in SF-12v1 version. All those responding in
version 2 that they had any problems (a little of the time, some of the time, most of the time, or all
5
of the time) were assigned as having problems (to match ‘yes’ in version 1), resulting in a higher
prevalence of role performance problems in 2003 and beyond. This explains the drop in SF-6D
scores seen in 2003 in the main paper. For the depression and energy questions, the original SF-6D
scoring randomly assigns those responding ‘a good bit of the time’ in SF-12v1 to adjacent response
categories, to match SF-12v2. That adjustment has little effect due to the similarity of scores
assigned to these adjacent categories.
An alternate unpublished item mapping has also been developed for the SF-6D to account
for differences between SF-12 versions 1 and 2 (program obtained via personal communication with
Janel Hanmer). With this alternate mapping, for role questions, all version 2 categories are scored as
version 1 ‘yes’ except “none of the time” and “a little of the time”. For depression, anxiety, and
energy questions, “a good bit of the time” responses are assigned a scoring value that is the average
of the “most” and “some” values. Figure 5A demonstrates the effect of this alternate mapping
(though 2008 only, focus is on period surrounding 2003 question change). This adjustment avoids
the drop in scores when switching to SF-2 version 2, slightly increasing rather than decreasing
scores. It yields scores close to those that would be obtained if no change in SF-6D scores was
assumed in 2003. Thus, SF-6D would not yield scores quite as much lower than other measures after
2003 if this alternate mapping were used.
Figure 5A: Mean SF-6D Scores Among those Age 25 and Over Using Original Scoring and Alternate
Mapping of SF-6D to Adjust Questions from SF-12 Versions 1 and 2
0.90
0.88
0.86
0.84
alternate mapping
(Hanmer)
0.82
0.80
Assume no change in
2003
0.78
0.76
official scoring
(shown in paper)
0.74
0.72
0.70
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
6
Table 1A: Symptom/Impairment Question wording Across Instruments
Survey/Year in which Impairment/Symptom was Measured and Question Wording
MEPS 2000-2010
Primary
activity
Social
activity
Self-care
Moderate: Limited in ability to
perform major activity (work at
a job, do housework, or go to
school) because of an
impairment or a physical or
mental health problem.
Severe: completely unable to do
this.
Besides the limitations we just
talked about, limited in
participating in social,
recreational, or family activities
because of an impairment or a
physical or mental health
problem.
Receive help or supervision with
personal care such as bathing,
dressing, or getting around the
house because of an impairment
or physical health problem.
SF-6D
During the past 4 weeks how
much of the time have you been
limited in the kind of work or
other regular daily activities as a
result of your physical health*
How much of the time have you
accomplished less than you
would like in your work or other
regular daily activities as a result
of any emotional problems (such
as feeling depressed or anxious)*
During the past 4 weeks, how
much of the time has
your physical health or emotional
problems interfered with your
social activities (like visiting
friends, relatives, etc.)?
--
EQ-5D
no problems with
performing usual
activities(e.g. work, study,
housework, family or
leisure activities)/some
problems with performing
usual activities/unable to
perform usual activities
HALex
--
--
no problems with selfcare/some problems
washing or dressing/unable
to wash or dress self
Receive help or supervision with
personal care such as bathing,
dressing, or getting around the
house because of an impairment or
physical health problem.
Routine
Needs
Receive help or supervision
using the telephone, paying
bills, taking medications,
preparing light meals, doing
laundry, or going shopping
Walking
Moderate: Unable or some/a lot
of difficulty walking a mile
and/or some difficulty walking 3
blocks. Severe: Unable or a lot
of difficulty walking 3 blocks.
Bending
Lifting
Standing
Reaching
Dexterity
--
Moderate activities, such as
moving a table, pushing a
vacuum cleaner, bowling, or
playing golf
Difficulty bending down or
stooping from a standing
position to pick up an object
from the floor or tie a shoe
(some/a lot/completely unable).
Difficulty lifting 10 lbs (some/a
lot/completely unable).
Difficulty standing for 20
minutes (some/a lot/completely
unable).
Difficulty reaching overhead
(some/a lot/completely unable).
Difficulty using fingers to grasp
(some/a lot/completely unable).
--
--
Receive help or supervision using
the telephone, paying bills, taking
medications, preparing light meals,
doing laundry, or going shopping
no problems in walking
about/some problems in
walking about/confined to
bed
--
--
--
--
--
--
--
--
--
--
8
Pain
Pain interfered with normal work (including both work outside the
home and housework) during the past 4 weeks
Not at all, a little bit, moderately, quite a bit, extremely (SF-12).
Depressive
Symptoms
Felt downhearted and blue during the past 4 weeks
Anxiety
Felt calm and peaceful during
the past 4 weeks only some, a
little, or none of the time (vs. a
good bit, most or all of the time)
none of the time, a little of the time, some of the time or a good bit
of the time, most of the time, or all of the time (SF-12v1)*
--
no pain or discomfort/
moderate pain or
discomfort/extreme pain
or discomfort
--
not anxious or depressed/
moderately anxious or
depressed/ extremely
anxious or depressed
--
--
--
--
--
--
--
(SF-12v1)*
Energy
Portion of the time person had a lot of energy during the past 4
weeks
none of the time, a little of the time, some of the time or a good bit
of the time, most of the time, or all of the time
(SF-12v1)*
Vision
Difficulty seeing (with
glasses or contacts, if
used): some difficulty
seeing or can not read
ordinary newspaper print
or can not recognize
familiar people standing
--
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two or three feet away or
blind.
Hearing
Cognition
Difficulty hearing (with
hearing aid, if used): some
difficulty hearing or can not
hear some or most things
people say or deaf.
Experience confusion or
memory loss such that it
interferes with daily
activities; have problems
making decisions to the
point that it interferes with
daily activities; require
supervision for own safety.
--
--
--
--
--
--
*These 2 role items have been combined to form a 4-level SF-6D of: no limitations, limitations because of physical problems, limitations because of emotional
problems, and limitations because of physical and emotional problems
*These questions were part of the SF-12 but were not used in the scoring of the SF-6D. Changes to questions on depressive symptoms, anxiety, and energy in 2003
occurred as a result of the switch from SF12 version 1 to version 2: The ‘good bit of the time’ response option was omitted, affecting the distribution of responses into
other categories. Depressive wording changed to ‘downhearted and depressed’.
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