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The clinical features of elderly-onset rheumatoid arthritis. A comparison with younger-onset disease of similar duration

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THE CLINICAL FEATURES OF ELDERLY-ONSET
RHEUMATOID ARTHRITIS
A Comparison With Younger-Onset Disease of Similar Duration
CHAD L. DEAL, ROBERT F. MEENAN, DON L. GOLDENBERG, JENNIFER J. ANDERSON,
BURTON SACK, ROBERT S. PASTAN, and ALAN S. COHEN
Patients with elderly-onset rheumatoid arthritis
(EORA) may represent a clinical subset of individuals
who differ prognostically and therapeutically from patients with younger-onset disease (YORA). In order to
test this hypothesis, we reviewed the records of 212
patients with rheumatoid arthritis and grouped them
according to age at onset above or below 60 years old.
Seventy-eight EORA patients and 134 YORA patients
with disease duration of 510 years were used for a
comparison of presenting features and disease outcome.
Abrupt onset occurred somewhat more frequently in
EORA, but was not associated with a significantly
different clinical course than was an insidious pcesentation in this older group. There were no differences
between the EORA and YORA groups in terms of mean
initial joint score, although the scores for the YORA
group had wider variation. An initial clinical pcesentation resembling polymyalgia rheumatica (PMR) was 4
From the Arthritis Center of Boston University, the Departments of Medicine, University and Boston City Hospitals, and
the Thorndike Memorial Laboratory, Boston City Hospital, Boston,
Massachusetts.
Supported by Multipurpose Arthritis Center grant AM20613 and Arthritis Training grant AM-07014 from the National
Institutes of Health, a Clinical Research Center grant from the
Arthritis Foundation, and an institutional grant from the Massachusetts Chapter of the Arthritis Foundation.
Chad L. Deal, MD: Assistant Professor of Medicine; Robert F. Meenan, MD, MPH: Associate Professor of Medicine; Don L.
Goldenberg, MD: Associate Professor of Medicine; Jennifer J.
Anderson, PhD: Assistant Research Professor of Medicine (Biostatistics); Burton Sack, MD: Associate Clinical Professor of Medicine;
Robert S. Pastan, MD: Clinical Instructor of Medicine; Alan S.
Cohen, MD: Conrad Wesselhoeft Professor of Medicine.
Address reprint requests to Chad L. Deal, MD, Case
Western Reserve University, Lakeside Hospital, 2073 Abington
Road, Cleveland, OH 44106.
Submitted for publication September 18, 1984; accepted in
revised form March 4. 1985.
Arthritis and Rheumatism, Vol. 28, No. 9 (September 1985)
times as frequent in EORA. Elderly patients were less
likely to have subcutaneous nodules or rheumatoid
factor at disease onset. At the final examination, the
EORA patients had lower joint scores and higher health
assessments despite similar courses of treatment. These
outcome differences persisted when patients with PMRlike presentations were excluded. Multivariate analyses
indicated that joint scores and disease duration made
important contributions to a better outcome of EORA,
whereas PMR presentation and abrupt onset did not.
After an adjustment was made for these 4 features, age
at onset was an important contribution to joint score
outcome. These results confirm the existence of important differences in onset, clinical features, and prognosis
between patients with EORA and those with YORA.
Longitudinal studies of rheumatoid arthritis
(RA) patients have identified historic, clinical, and
laboratory findings which have important associations
with disease severity and outcome. For example, the
presence of rheumatoid factor (seropositive RA) identifies a group of patients with greater functional disability, greater erosive disease, and higher frequency
of use of remittive agents (1-3). Sex, race, type of onset, rheumatoid nodules, antinuclear antibodies, and
HLA type have also been identified as important determinants of disease outcome (4-7). However, age as a
determinant of disease course and outcome is controversial. Several reports have claimed that patients
whose rheumatoid arthritis begins later in life (generally defined as after age 60) represent a clinical subset of
patients with important differences in presentation,
disease manifestations, and prognosis compared with
patients who develop RA at a younger age, while other
studies have found no significant differences (8-13).
988
DEAL ET AL
The present study attempts to clarify this issue
by a direct comparison of the presentation and course
of elderly-onset rheumatoid arthritis (EORA) and
younger-onset rheumatoid arthritis (YORA). It differs
from previous studies of EORA in that the sample size
is larger, the subjects are drawn from both academic
and community settings, and adjustments were made
for differences in duration of disease. The results
confirm that there are important differences in presentation and clinical features between EORA and YORA
patients. With controlling for disease duration and
initial severity of disease, there are still important
differences in outcome between the 2 groups, despite
highly similar courses of treatment. The results support the theory that age at onset is an important factor
which influences outcome in rheumatoid arthritis.
PATIENTS AND METHODS
We reviewed the charts of 300 patients with RA who
were being followed by 4 rheumatologists in the Boston area.
Two rheumatologists based at a medical center were following 55 (20%) of the subjects, and 2 rheumatologists based in
the community were following 245 patients (80%). All 300
patients met the American Rheumatism Association (ARA)
criteria for definite or classic RA (14). Subjects were categorized as having EORA or YORA based on a cutoff age of 60.
We chose this cutoff since it represented the modal age used
by previous investigators who have studied EORA.
A subset of RA patients with disease duration of 5 1 0
years at the time of the study was selected for analysis. This
allowed analysis of groups with similar disease duration
since duration has a major impact on clinical manifestations
and the outcome of RA (15). The final study sample comprised 212 subjects (71% of the total), including 134 (62%) of
the YORA group and 78 (95%) of the EORA group.
A standard chart review procedure was used to
collect data on the following variables from the initial and
most recent routine visit (final visit) of each subject: type of
onset, duration of morning stiffness (>30 minutes), presence
of constitutional symptoms, subcutaneous nodules, joint
score, and laboratory values (including complete blood
count, erythrocyte sedimentation rate, and rheumatoid factor [RF]). Type of onset was classified as abrupt if the
arthritis reached full intensity within 2 weeks of the initial
symptoms. Joint score was based on a 0-3 grading of
swelling or tenderness for 13joints or joint groups (proximal
interphalangeal/metacarpophalangeal,wrists , elbows, shoulders, acromioclavicular, sternoclavicular, temporomandibular, toes, ankles, knees, hips, cervical spine, lumbar spine).
A positive joint on either side of the body resulted in a score
of I (mild), 2 (moderate), or 3 (severe) for that joint pair or
group, so that the score for joint count could potentially
range from 0-39. For example, severe tenderness in all 10
metacarpal joints resulted in a joint score of 3, as did
bilateral severe tenderness of the wrists. Gradings for involved joints had been recorded in a large majority of patient
charts; therefore these scores could be used directly. When
exact grades were not available, scores were estimated from
the narrative description. One author (CLD) reviewed all
charts.
Data were also collected on all medications, including those used before the first visit and those used during the
interval between the initial and most recent visit. Information was gathered on whether the patient had had orthopedic
surgery and whether each patient had been referred for
physical and/or occupational therapy. Overall outcome was
analyzed by using 4 measures of current status at the time of
the final visit. These included the physician’s overall assessment, the patient’s overall assessment, the patient’s ARA
functional class, and the joint score. The first 2 estimates
were based on a 5-point scale ranging from very good to very
poor. The attending physicians estimated the patient’s functional class using the standard 4-point scale (16).
Statistical analysis focused on differences between
groaps, using t-tests and analysis of covariance for continuous variables and chi-square tests for categorical variables.
The t-tests were based on assumptions of independent
samples and unequal variances, utilizing 2-tailed probability.
The chi-square tests used Yates’ correction.
Since multiple comparisons were performed, P values for a Type I error were given for each reported difference, and the Bonferroni adjustment was applied to maintain
an overall significance level of 0.05 (17). The analysis of
covariance was used to adjust for presenting features that
would possibly confound differences in final joint count
between the age at onset groups. The significance of these
factors was tested using t-tests. The factors adjusted for
included initial joint count, which has a quadratic relationship with final joint count in these data. Both linear and
quadratic terms were included in adjusting for this variable
(18).
RESULTS
The study group consisted of 53 men and 159
women. The age at disease onset in the EORA subSD (range 60-84). The
jects was 67.2 4.7, mean
age at disease onset in the YORA patients was 46.6 ?
10.0, mean
SD (range 20-59). Seventy-eight subjects were 2 6 0 at disease onset, 134 were <60 at
disease onset; 34 patients were between the ages of 55
and 60, and another 26 were between 50 and 55.
Women were predominant in both groups. The average disease duration for both groups was 4.8 +: 3.1
years (4.06 2.87 for EORA; 5.25 3.17 for YORA).
Presenting symptoms. An abrupt onset, with
symptoms peaking in days to weeks, occurred nearly
twice as often in the EORA group (Table 1) (27%
versus 14%; P = 0.024). Morning stiffness >30 minutes duration was extremely common in both groups.
There were no major differences in constitutional
symptoms such as fatigue ( P = 0.185) or weight loss
(P = 0.169). The groups were also very similar in
terms of selected extraarticular symptoms of RA,
*
*
*
*
*
ELDERLY-ONSET AND YOUNGER-ONSET RA
Table 1. Presenting features of elderly-onset rheumatoid arthritis
(EORA) and younger-onset rheumatoid arthritis (YORA)*
~
~~
~
EORA
Presenting feature
(n = 78)
67.2 lr 4.7
Age at onset (years)
Disease duration at initial visit
1.1 % 1.9
(years)
69%
% female
21%
Positive family history
27%
Abrupt onset
85%
Morning stiffness
23%
PMR symptomst
4.9 f 2.6
Total joint score
24%
Small joint disease5
14%
Large joint disease
6%
Subcutaneous nodules
52 f 1.6
Erythrocyte sedimentation rate
48%
Positive rheumatoid factor
YORA
(n = 134)
46.6
f
P
-
10.0
1.9 f 2.5
78%
24%
14%
90%
5%
5.1 f 3.6
46%
8%
20%
40.7 f 23.6
72%
0.005
0.188
0.782
0.024
0.309
O.OOO$
0.696
0.003t
0.186
0.016
0.008
0.001$
* Values are mean ? standard deviation unless designated otherwise.
t Polymyalgia rheumatica (PMR) symptoms are positive if all 4 of
the following are true: involvement of shoulders or hips, nodules
absent, erythrocyte sedimentation rate >50, latex fixation titer
<1:20.
i: For significance at the 0.05 level, with 13 comparisons, the
Bonferroni adjustment requires a P value of s0.05/13 = 0.0038.
5 Small joint disease = involvement of fingers and toes; large joint
disease = involvement of shoulders and hips.
including dry eyes (7% overall), dry mouth (4% overall), and carpal tunnel syndrome (10% overall).
The initial physical examination revealed significant differences between the 2 groups. The joint score
at the time of the first visit was nearly identical in the 2
groups (4.9 ? 2.6 in the EORA group versus 5.1 3.6
in the YORA group; P = 0.696), but the spread of
values was much greater in the YORA group (P <
0.003 in the F-distribution test for equality of variances). The pattern of joint involvement was also
somewhat different. Younger patients were twice as
likely to have small joint disease with evidence of
active inflammation in both finger and toe joints (46%
versus 24%; P = 0.0025). Elderly patients tended to
have more arthritis in both hips and shoulders (14%
versus 8%; P = 0.186). This latter difference was
primarily due to a higher frequency of shoulder synovitis in the EORA group (56% versus 36%; P = 0.060).
The EORA patients were less apt to have subcutaneous nodules present at the initial examination (6%
versus 20%; P = 0.016).
The EORA group had a higher initial erythrocyte sedimentation rate (ESR) (P = 0.008) and was
significantly less likely to have a positive RF ( P =
0.001). There were no differences between groups in
initial hematocrit value (mean = 38.7), white blood cell
*
989
count (7,500/mm3), or frequency of antinuclear antibody (ANA) titers >1: 16 (7.5%).
A polymyalgia rheumatica (PMR)-like presentation was defined as the presence of all 4 of the
following features: shoulder or hip synovitis, absence
of nodules, ESR >50 mm/hour, and negative RF. All
of these features were present in 23% of the EORA
group, compared with 5% of the YORA group (P =
0.0002). This difference was also apparent if the number of PMR features was treated as a continuous
variable. In this case, the EORA group exhibited 2.5 k
1.1 of the features, whereas the YORA group had only
1.7 ’-+ 0.9 (P < 0.001).
Therapy. The younger and older patients were
treated in a similar fashion (Table 2). The percentage
of patients in each group who were treated with any
“second line” drug was virtually identical. While
steroids were used somewhat more often by the elderly-onset group, gold injections, penicillamine, and
cytotoxic drugs tended to be used more frequently by
the younger patients. These differences, however,
were relatively small and none were clearly significant. The younger group was only slightly more likely
to have undergone orthopedic surgery or occupational
therapy, but was substantially more likely to have
received physical therapy. The overall picture, however, is one of nearly identical treatment during the first
years of disease, regardless of the age at onset.
Outcome. The outcome of the elderly-onset
group assessed at the last visit was significantly better
than that of the younger-onset group across a variety
of pertinent disease outcome measures (Table 3). The
elderly subjects were much less apt to experience
morning stiffness or fatigue, despite the fact that
fatigue tended to be more common in the EORA group
at the initial visit.
Table 2. Treatment of elderly-onset rheumatoid arthritis (EORA)
and younger-onset rheumatoid arthritis (YORA)
Treatment
Second line drugs
H ydroxychloroquine
Gold injections
Oral steroids
Penicillamine
Cytotoxic drugs*
Orthopedic surgery
Physical therapy
Occupational therapy
EORA, %
(n = 78)
YORA, %
(n = 134)
P
92
80
25
64
6
91
84
36
59
11
5
14
50
20
0.39
0.50
0.13
0.57
0.40
0.13
0.26
0.06
0.40
0
8
35
14
* Includes azathioprine, cyclophosphamide, chlorambucil, or methotrexate.
DEAL ET AL
990
Table 3. Outcome comparison of elderly-onset rheumatoid arthritis (EORA) and younger-onset rheumatoid arthritis (YORA) in subjects with
disease duration of 10 years or less*
Excluding polymyalgia rheumatica
presentations
All subjects
Outcome measure
EORA
(n = 78)
YORA
(n = 134)
P
EORA
(n = 61)
YORA
(n = 127)
P
Disease duration (years)
Morning stiffness
Fatigue
Total joint score
Small joint disease$
Large joint disease
No active joints
Subcutaneous nodules
Erythrocyte sedimentation rate
Physician assessment§
Patient assessment5
ARA functional class I or 27
4.1 f 2.87
21%
3%
1.9 2 2.2
7%
1%
36%
17%
24.4 f 26.0
86%
84%
94%
5.25 t 3.17
42%
15%
3.3 f 3.3
21%
4%
20%
33%
27.9 2 22.0
72%
70%
83%
0.006
0.0031
0.01 1
0.000t
0.010
0.553
0.031
0.018
0.388
0.032
0.038
0.039
4.4 f 3.0
25%
3%
2.0 2 2.2
8%
2%
38%
28%
25.1 f 29.2
84%
82%
94%
5.4 f 3.1
42%
15%
3.3 & 3.3
21%
3%
20%
35%
27.9 t 22.3
71%
70%
82%
0.041
0.033
0.030
0.002t
0.050
0.926
0.015
0.104
0.597
0.097
0.118
0.056
~~
~~
* Values are mean 2 standard deviation unless designated otherwise.
t For significance at the 0.05 level, with 12 comparisons, the Bonferroni adjustment requires a P value of <0.05/12
$ Small joint disease = involvement
§
of fingers and toes; large joint disease
=
=
0.0042.
involvement of shoulders and hips.
Percent rated as good or very good.
= American Rheumatism Association.
7 ARA
The total joint score at the time of the final visit
was significantly lower in the older group (1.9 5 2.2
versus 3.3 k 3.3; P < O.OOO), and the EORA patients
were much more apt to have no active joints (36%
versus 20%; P = 0.031). Eighty-seven percent of the
EORA group and 74% of the YORA group had a lower
final joint score compared with their initial joint score
(P = 0.039). The younger patients continued to have
more evidence of small joint involvement, while the
older patients no longer exhibited a high frequency of
large joint disease, The YORA group had nearly twice
the frequency of subcutaneous nodules (17% versus
33%; P = 0.018). It is possible that the better outcome
in the EORA group related to shorter disease duration.
However, a separate analysis of subjects (EORA [n =
541 and YORA [n = 691) with disease duration 5 5
years, in which the mean duration of disease was
nearly identical in the 2 groups (2.50 years in the
EORA group versus 2.56 years in the YORA group;
P = 0.85), continued to reveal better outcome in the
EORA patients.
Laboratory findings in the 2 groups were quite
similar. The final ESR in the elderly-onset subjects
was found to be nearly equal that of the younger-onset
patients, despite the fact that the initial ESR in the
older group had been significantly higher. Positive RF
and positive ANA were present in both groups, but
these observations were frequently omitted at the last
visit.
The tendency of the elderly-onset group to do
better on specific disease activity measures is reflected
in the fact that they also fared much better in terms of
overall disease status estimates. Patients in the elderly-onset group were much more likely to rate their
status as “good” or “very good” than were patients in
the YORA group, and were more likely to be rated in
the top 2 functional classes by their physicians.
These outcome analyses were repeated after
eliminating the 24 subjects (17 EORA, 7 YORA) who
had a PMR-like presentation. These results are shown
in Table 3. Only minor alterations in the differences
previously described between EORA and YORA
groups were seen in this revised analysis. For example, morning stiffness was no longer significantly less
common in the EORA group. However, the outcome
for the EORA group continued to be substantially
better on all measures even when the subjects with a
PMR-like presentation were omitted.
Because of the tendency of elderly patients to
have a much better outcome compared with younger
patients, an attempt was made to identify the factors
which might account for this difference. One possible
explanation is that abrupt-onset disease is more common in the elderly-onset group, and that this type of
RA tends, in general, to have a better outcome.
Another plausible explanation is that the PMR-like
disease frequently found in the elderly is, in fact,
polymyalgia rheumatica rather than RA and therefore
could be expected to have a more benign course.
In addition to the differences in presenting
ELDERLY-ONSET AND YOUNGER-ONSET RA
Table 4.
99 1
Analysis of variance of joint score outcome in elderly-onset and younger-onset rheumatoid arthritis groups
Excluding polymyalgia rheumatica (PMR)
presentations?
All subjects*
Factorkovariate
Age at onset
Initial joint score
Linear effect
Quadratic effect
Disease duration
Mode of onset
PMR symptomst
Sex
Constant
Regression
coefficient
Standardized
regression
coefficient
-0.04
-0. I8
-0.19
0.05
0.11
-0.48
-0.46
-0.16
3.64
-0.23
0.73
0.13
-0.07
-0.06
-0.03
* n = 187; adjusted R2 = 0.365.
t n = 174; adjusted RZ = 0.431.
t PMR symptoms are positive if all 4 of the following are true:
P
Regression
coefficient
Standardized
regression
coefficient
P
0.004
-0.30
-0.14
0.017
0.286
0.001
0.051
0.249
0.378
0.661
0.000
-0.24
-0.06
0.92
-0.51
-0.28
0.87
-0.10
0.07
0.162
0.001
0.099
0.267
-
-
-
-0. I5
-0.02
0.687
0.000
-
3.43
involvement of shoulders or hips, nodules absent, erythrocyte sedimentation
rate >50, rheumatoid factor titer < 1 :20.
characteristics, there were differences between the
EORA and YORA groups in the distribution of both
initial joint counts and the total duration of disease,
each of which is related to outcome. In order to adjust
for each of these factors in a comparison of the 2
groups, they were included as covariates in an analysis
of variance using final joint count as the outcome
(dependent) variable.
The results of the multivariate outcome analyses are presented in Table 4. (The left half of the table
includes all subjects, the right half excludes those with
PMR-like presentations. There were no substantial
differences between the 2 sets of findings). Initial joint
score and disease duration were strongly associated
with the joint score outcome, whereas the associations
of abrupt onset and PMR features were not. After
covariance adjustment for each of these factors and for
sex, there remained a linear effect of age at onset
(-0.04 t 0.01). This translates to a final joint score 1
unit lower for every 28.5-year increase in age at onset.
Analysis using the 4 PMR components (RF titer
<1:20, absent nodules, ESR >50, hip or shoulder
arthritis) as separate variables indicated that none
made a significant contribution to outcome. The lower
frequency of seropositive RA in the EORA group did
not explain the better outcome, since the inclusion of a
separate RF term in the regression equation at either
the 1 :20 or 1 :80 titer level showed no effect. Additional covariance analysis using 3 alternative outcome
measures (absence of active joints at final visit, physician’s assessment, and patient assessment) also demonstrated no effect for the PMR variables.
A comparison of joint outcomes for the YORA
and EORA groups was then carried out within each of
Table 5. Stratified comparison of joint outcome in elderly-onset rheumatoid arthritis (EORA) and
younger-onset rheumatoid arthritis (YORA) groutx
Final joint scores
Stratum*
EORA
Y ORA
Low joint score/short duration
0.9 2 1.15t
(n = 28)
1.92 ? 2.54
(n = 12)
2.20 2.61
(n = 25)
3.25 2 2.30
(n = 12)
1.57 1.47
(n = 46)
2.31 2.53
(n = 26)
5.00 2 3.66
(n = 22)
5.25 2 3.64
(n = 36)
Low joint score/long duration
High joint score/short duration
High joint score/long duration
*
*
*
Difference
P
0.64
0.042
0.39
0.663
2.80
0.002
2 .00
0.034
* Low joint score if initial count 5 4 ; high joint score if >4. Short duration if duration at last visit 5 5
years; long duration if >5 years.
t Values expressed as mean standard deviation.
992
DEAL ET AL
4 strata, based on low or high initial joint score (<4 or
:>4) and long or short disease duration (<5 years or >5
years), since these strata were more uniform than the
data set as a whole, with respect to these 2 measures.
The results shown in Table 5 confirm that joint count
outcome differences between the YORA and EORA
groups depend on disease duration and on initial joint
scores. These results indicate that, given low joint
score and short duration, or any of the other 3 combinations of these 2 factors, EORA joint outcomes
were always better than YORA outcomes. For those
with low initial joint score, for example, there were
final joint count differences of 0.64 ( P = 0.042)
and 0.39 P = 0.663) for the shorter and longer duration
strata, respectively. For those with higher initial joint
counts, the corresponding outcome differences were
2.80 ( P = 0.002) and 2.00 ( P = 0.034). Thus the
outcome differences between EORA and YORA
groups are particularly dependent on initial joint score.
DISCUSSION
The results of this study provided new information with which to address 2 important questions
regarding elderly-onset rheumatoid arthritis. The first
question is the longstanding one of whether elderlyonset rheumatoid arthritis is a substantially different
disease than that found in younger people. Our results
revealed that there are important differences in presentation and outcome when these 2 groups are compared. The second question is whether these differences between EORA and YORA are solely due to the
fact that much of what is diagnosed as elderly-onset
RA is actually polymyalgia rheumatica, a disease with
a substantially more favorable outcome than rheumatoid arthritis. Our findings were not consistent with
this view, and tended to support the theory that
elderly-onset rheumatoid arthritis is a reasonably distinct entity.
The issue of whether RA is different when it
appears in different age groups has been debated since
Cecil first claimed that RA in the aged did not differ
essentially from that seen in younger patients (13).
Subsequent studies, however, have tended to support
the notion that there are differences between elderlyonset and earlier-onset disease. Differences in the
frequencies of such features as abrupt onset, sex
ratios, proximal joint involvement, and erythrocyte
sedimentation rate have been noted (10-12). The researchers, however, have disagreed on the prognostic
implications of elderly-onset disease.
Most studies of EORA have not included a
direct YORA comparison group and thus their conclusions are open to serious question. However, 2 of
them have, as in the present study, involved a YORA
comparison group (9,lO). Both used age 60 as a
criterion for EORA, and both concluded that there
were differences in presentation between EORA and
YORA and a more favorable prognosis in the former.
In each of these studies, however, there was a disconcerting difference in disease duration between the 2
groups, with YORA patients having substantially longer durations. The more favorable outcome of the older
group may have been primarily due to this factor
alone. The present study provides stronger evidence
of the favorable outcome in EORA by using a direct
comparison group with similar disease duration, by
more directly addressing the potential for misdiagnosis
of PMR as EORA, and by analyzing the impact of
selected factors in a multivariate analysis.
Our study clearly indicated that there are important differences in the presenting symptoms and in
the initial physical and laboratory findings in patients
with EORA. Our results confirm the finding that
abrupt disease onset is substantially more frequent in
elderly-onset disease and that large joint disease,
particularly of the shoulder girdle, tends to be more
common. In contrast, small joint disease is significantly more frequent in the younger-onset group. The
younger patients, in general, have a condition that
more closely resembles “classic” rheumatoid arthritis, with small joint disease, subcutaneous nodules,
and positive latex fixation titers. A substantial proportion of the elderly-onset group have features which are
similar to those found in polymyalgia rheumatica.
Our results support the argument that the outcome of elderly-onset rheumatoid arthritis is substantially better than that of disease beginning at a younger
age. In our large group, better outcomes for the elderly
were found in all parameters including symptoms,
joint evaluations, erythrocyte sedimentation rate
changes, and overall assessment by both physicians
and patients. These more favorable outcomes occurred despite the fact that the 2 groups were treated
in a highly similar fashion in terms of drug, surgery,
and other therapies.
Why does EORA seem to have a more favorable prognosis? The presence of rheumatoid factor has
been a fairly consistent predictor of more severe disease
in patients with rheumatoid arthritis when compared
with patients without RF (2,3). Fewer EORA patients
had seropositive disease (48%, versus 76% of YORA
ELDERLY-ONSET AND YOUNGER-ONSET RA
patients; P = 0.0008), but analysis using rheumatoid
factor as a variable revealed that it did not account for a
better outcome. Although females have been shown to
have less favorable outcomes (4), sex ratios were not
substantially different in our study. Race also did not
differ significantly between the 2 groups.
Abrupt onset, which occurred more frequently
in those with EORA, did not account for a better
prognosis. There are conflicting findings in the literature on the effect of abrupt onset on disease outcome.
Corrigan found that 26% of EORA patients had an
abrupt onset with severe constitutional symptoms and
that all experienced disease remission within 18
months (8). Terkeltaub (lo), in contrast, found no
significant joint count differences between patients
with acute and those with nonacute disease in either
EORA or YORA groups. Both studies used 48 hours
or less as the dividing point between acute and nonacute disease, whereas the present study used 2
weeks. These digerences in definition may account for
some of the disagreement about the effect of this factor
on outcome.
Our findings confirm the notion that features of
PMR are quite common in EORA (14,19-24), but we
believe that the patients with these features in this
study had true rheumatoid arthritis with features of
polymyalgia, rather than having PMR which was confused with rheumatoid arthritis. Diagnosis was made
by rheumatologists, each subject met the ARA criteria
for definite or classic RA, no patient had symptoms of
temporal arteritis or required a temporal artery biopsy
during an average disease duration of 5 years, and the
percentage of patients with PMR features who were
treated with steroids during this period was not significantly different from the percentage of other patients
so treated (74% versus 62%; P = 0.33). Most importantly, the presence of PMR features had minimal
impact on outcome when we controlled for age at
onset.
If a substantial number of these elderly individuals actually had PMR with articular manifestations,
one would expect the better outcome to be explained
in large part by the presence of the PMR features. This
did not prove to be the case. Separate outcome
analyses in which all subjects with PMR presentations
were excluded showed nearly identical findings regarding the differences between the EORA and YORA
groups. The effect of PMR features on outcome found
in this study is consistent with the interpretation that
elderly-onset RA is a relatively distinct subset of this
disease which frequently exhibits PMR-like features
993
and which tends to have a better prognosis. This is not
to say that all or even most elderly patients who
present with a combination of RA and PMR features
actually have EORA. The clinician must remember
that PMR is a frequent rheumatic problem in the
elderly and that it may mimic RA in some cases.
In summary, the study has reviewed the clinical
features and outcome of patients with elderly-onset
rheumatoid arthritis, and has compared them with a
younger-onset group with similar disease duration.
Our findings support the theory that EORA is a
definable clinical subset of rheumatoid arthritis which
differs in initial clinical features and subsequent outcome from that found in younger subjects. Age at
onset appears to be an important determinant of
prognosis in RA, and this is not solely attributable to
the possible effects of abrupt onset or PMR-like disease.
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