Gender, Depression, and Ankylosing Spondylitis

\die Helen Barlow, Stephen John Macey, and George Robert Struthers

Depression has been established as a common reac- tion to rheumatoid arthritis but has rarely been in- vestigated among people with other forms of arthritis. The present study examined the prevalence and de- terminants of depressive symptoms in people with ankyylosing spondylitis, focusing on gender differences and set in the context of widely held medical views concerning the psychosocial nature of ankylosing spondylitis patients. Results showed that approxi- mately one third of the ankylosing spondylitis patients reported a high level of depressive symptoms and that women reported more depression than men. No ev- idence was found to support the stereotype of the “typical” ankylosing spondylitis patient as being Jess dep.ressed than people with other forms of arthritis. Pain was found to be a major determinant of depres- sion for women, but was of lesser importance for men. The implications of these findings are discussed.

Key words: Depression; Ankylosing spondylitis; Gen- der; Pain.

An association between depression and arthritis is well-established [I] with symptoms of depression de- veloping after the onset of pain and disability [Z]. How- ever, much of the evidence supporting this relation- ship has derived from studies of people with

Julie Helen Barlon, BA, and Stephen John Macey, BSC, MSC, are at the Department of Social Science and Policy Studies, Cov- entry University, Priory Street, Coventry, England. George Robert Struthers, MA, MB, Bchir, MRCP, is at the Department of Rheu- matology, Coventry & Warwickshire Hospital, Stoney Stanton Road, Coventry, England.

Address correspondence to Julie Helen Barlow, BA, Department of Social Science and Policy Studies, Coventry University, Priory Street, Coventry CV1 5FB, England.

Suhmitted for publication February 25,1992; accepted July 8,1992. 0 1493 by the Arthritis Foundation.

rheumatoid arthritis (RA). The psychological aspects of other forms of arthritis, such as ankylosing spon- dylitis (AS], have received little direct attention. Stud- ies of RA are based on samples consisting mainly of women, reflecting the predominance of RA among women. Can it be assumed that similar results would be found among people with AS, where women form a minority? This question is especially salient when considered in the context of the greater reported in- cidenc:e of depressive symptoms among women in general [3].

STEREOTYPES AND ANKYLOSING SPONDYLITIS

Although patient associations such as the National Ankylosing Spondylitis Society (NASS, United King- dom] and the Ankylosing Spondylitis Association (United States] believe depression to be a significant problem for many of their members, widely held med- ical beliefs suggest that AS patients are less depressed than people with other forms of arthritis. Despite a lack of systematic research into the psychosocial na- ture of AS patients, beliefs arising from clinical ex- perience and anecdotal evidence have been consoli- dated into a stereotype of the “typical” AS patient. This patient is perceived as being male, active, well- educai ed, highly motivated, self-reliant and, com- pared to other patients with arthritis, is less depressed, less emotional, more socially oriented, and has a high- er pain threshold [4,5]. It may not be entirely coinci- dental that this “typical” AS patient would be ideally suited to the active style of treatment for AS, which requires the patient to carry out a regular program of exercise.

It is now recognized that the diagnosis of AS is often missed in women and that more women have the dis-

0893-7524/93/$5.00 45

46 Barlow et al. Vol. 6 , No. 1, March 1993

ease than has been acknowledged in the past. Re- ported sex ratios are in the region of three men to one woman [6]. The traditional and widely held belief that fiS is a disease of young men is the most common explanation for the underestimation of AS in women. finkylosing spondylitis is a difficult disease to diag- nose, particularly in women. There is a relatively long delay between the onset of symptoms and diagnosis. Where diagnosis is made on the basis of patient history and clinical judgment, the beliefs of the clinician may be important in determining diagnostic probability.

Psychological distress has consistently been asso- ciated with an increase in physical symptoms [7]. In- teraction between physical disease [arthritis) and psy- c hological distress (depression] may amplify and exacerbate the physical process, thus increasing re- ports of pain and discomfort. The strength of the as- sociation between depression and chronic pain is the subject of controversy: some researchers find a strong positive relationship [8], whereas others report a weak relationship [9]. The association between pain and de- pression among people with AS has not been exam- ined.

Additional psychological variables associated with depression are self-esteem 1101 and health locus of control beliefs [IT] . The latter refers to the locus or place of perceived control over one’s health and has been related to self-care activities among people with A S [U]. To summarize, there are many areas of un- certainty, controversy, and pronounced, but unsub- sl.antiated, views relating to AS that may affect both physical and psychological well-being.

STUDY OBJECTIVES AND HYPOTHESES

The purpose of the study was to provide an initial examination of the prevalence and determinants of depression in a sample of people with AS focusing on possible gender differences and set in the context of widely held beliefs regarding the “typical” AS patient. The specific questions and hypotheses were as follows. What is the level and prevalence of depression among people with AS? Are there gender differences relating to depression in this patient group? Are people with A S less depressed than other arthritis patients, as sug- gested by widely held medical beliefs? What are the main determinants of depression in AS patients? Do these determinants differ for men and women? What is the relationship between pain and depression in AS patients? Is this relationship the same for men and women with AS? We hypothesized that people with A S would report higher levels of depression than is found in community samples. Within the study sam-

ple, we predicted that more women than men would be at risk of developing clinical depression.

METHODS

Subjects All AS patients (American College of Rheumatology

criteria] attending local rheumatology clinics, local AS self-help groups, and the NASS Annual Symposium in 1990 were invited to participate in the research. This approach was adopted according to the recom- mendations of Gran and Husby [13] to avoid possible referral, bias resulting from recruiting patients solely through rheumatologic institutions that treat patients with more severe disease. Comparisons were made between NASS members and nonmembers, self-help group members and nonmembers, and those recruited through rheumatology clinics versus those recruited through NASS and self-help groups. In the United Kingdom, patients with AS are referred to self-help AS exercise groups by rheumatology clinics and/or physiot’herapy departments. Members of such self-help groups also tend to be those who attend local rheu- matology clinics. The only study variable to distinguish between self-help exercise group participants and nonparticipants was that of exercise frequency. Self- help group members were found to exercise more often than nonmembers [means = 4.47 and 3.36, re- spectively; t = -2.16, P = 0.03, two-tailed test], a dif- ference that could be accounted for by weekly atten- dance at a self-help group. No differences, on any of the studly variables, were found between nonmembers and members of NASS or between those recruited through rheumatology clinics and other sources. The sample was considered to be homogeneous for the purposes of this investigation.

The study was a cross-sectional survey. Data were collected by self-administered questionnaires. Re- sponse rate was 72%. The sample consisted of 129 men, 48 women; sex ratio, 2.7 M:l F; mean age, M =

43.9 years and F = 43.5 years, mean disease duration, M = 1’3.8 years and F = 17.4 years. The sex ratio corresponds to that reported in the literature: 3 M:l F. The sarnple was thus assumed to be representative of the AS population. There were no indications of a differential response rate between men and women.

Measures The Center for Epidemiological Studies-Depression

[CES-D) scale [14] was designed to measure symptoms of depression, rather than clinical depression, in the general population and was chosen because it contains fewer somatic items than many other instruments. The

.4rthritis Care and Research Gender, Depression, and AS 47

TAB'LE 1

Comparison Between Men and Women on Disease Rela.ted Variables

Variables

Age Duration Age at onset Diagnostic delay AS pain MPQ Disability

Men (mean)

43.9 [years] 19.8 (years) 24.3 (years]

7.3 [years] 3.0 6.9 2.6

Women (mean)

43.5 [years) 17.4 [years] 26.2 [years] 8.2 [years) 3.2 7.5 3.0

Signifi- t cance

NS NS NS NS NS NS

2.22 0.03

AS, ankylosing spontfylitis; MPQ. McGill pain questionnaire; NS. not sig- iifica,it.

CES-D scale does not significantly bias estimates of prevalence, severity, or determinants of depressive symptoms in arthritis patients [15] and it measures a c:om,parable underlying dimension of depression in both men and women [16].

Multi-Dimensional Health Locus of Control (MHLC) Scalres [17] measure perceived control over health on three dimensions: beliefs relating to personal control over health; beliefs relating to external control of health hy powerful others; and beliefs relating to the influ- ence of chance, luck, or fate over health.

The Carlson Adjective Checklist [18] assesses self- esteem on two dimensions. The equal numbers of items

relating to social and personal self-esteem were de- signed to remove the sex bias often found in other self-esteem measures. The scale was scored in the manner recommended by Skevington et al. 1191.

The CES-D, MHLC scales, and the Carlson Adjec- tive Checklist have been demonstrated to be reliable and valid, and have been used in studies of other chronic disease samples including arthritis patients.

Health status in AS is difficult to measure. At pres- ent, there is no accepted gold standard for either clin- ical or functional assessment [ZO]. However, self-re- port ratings of health status have been shown to be of value 1.211 and were used in this study. Pain was as- sessed by the McGill pain questionnaire (MPQ), a fre- quent1,y used instrument that assesses pain intensity [ZZ], arid a rating scale assessing the amount of pain experienced due to AS. Pain rating scales have been shown to perform similarly to other methods of mea- suring pain such as visual analog scales 1231. Disability was indicated by a rating of the extent to which AS affects the patient's everyday life. Disease-related items included duration and age at onset. Health behavior was assessed by the frequency of exercise per week. Statistical analysis was carried out using SPSS.

RESULTS

Comparisons were made between the men and women in terms of disease-related variables. No sig-

Figure 1. Comparison of those at risk of developing clinical depression. Community figures adapted from Frerichs et al. (31; rheuinatoid arthritis figures adapted from Blalock et al. [2].

48 Barlow et a). Vol. 6, No. 1, March 1993

TABLE 2

Correlation Matrix for Women ~~ ~ ~~~

Variables

1 2 3 4 5 6 7 0 9 10 _____

1 Depression 2 AS Pain 3 MPQ 4 Disability 5 IHLC 6 PHLC 7 CHLC 8 Social SE 9 Personal SE

10 Exercise

~~

0.56" 0.65" 0.47" NS NS 0.35b NS 0.42h 0.72" NS NS 0.34b NS

0.37'' -0.32' NS 0.28' NS -0.27' NS 0.35b NS

-0.25- -0.30" NS NS NS

NS

NS NS NS

0.28' NS NS NS

0.2gL

NS NS

O.3lc NS NS NS NS

0.25L 0.26"

" P < 0.001. b P < 0.01. ' P < 0.05. AS, ankylosing spondylitis; MPQ. McGill Pain Questionnaire; IHLC. internal health locus of control; PHLC, powerful others health locus of control; CHLC,

chance health locus of control, SE, self esteem; NS. not significant.

riificant differences were found in relation to age, du- ration of disease, age at onset, diagnostic delay, or measures of pain (Table 11. The mean score on ratings of disability was found to be slightly higher for women (mean = 2.6 for men, mean = 3.0 for women: t = 2.22, I' < 0.028). The results suggest the disease-related pro- files of the male and female AS patients in this study are similar.

Regarding the psychological variables, the only sig- nificant difference between the women and men was in the level of symptoms of depression. Women re- ported significantly higher levels of depressive symp- toms (means = 15.0 for women, 10.4 for men; t = 2.7, P < 0.006, two-tailed test). No significant differences were found in terms of control over health, self-es- teem. or frequency of exercise per week. Thirty-one percent of the sample (men and women] scored >16 on the CES-D scale (16 is the recommended cut-off point above which respondents are at risk of devel- oping clinical depression [IS]). The percentages of men and women found to be at risk were 26% and 4670, respectively (xz = 6.63, P < 0.01, see Figure 1).

The correlation matrix for women AS patients (Ta- ble 2) shows that depressive symptomatology is posi- tively correlated with measures of pain, disability, and chance control.

The variables correlating significantly with depres- sion for women were entered into a stepwise multiple regression on CES-D scores. The only significant pre- dictors of depression were found to be the two mea- sures of pain (see Table 31, which explained 46.31% of the variance in CES-D scores for women.

The same procedure was repeated for men. The correlation matrix for men shows that depression cor-

related positively with measures of pain and disability; chance health locus of control and was negatively cor- related with internal locus of control (Table 4). Weak correla.tions were found between depression and pow- erful others health locus of control, social self-esteem, personal self-esteem, and exercise frequency.

The variables correlating significantly with depres- sion were entered into a stepwise multiple regression procedure. Significant predictors of depression in men were found to be disability, MPQ, exercise frequency, internal control, and personal self-esteem, which com- bined to explain a total of 31.35% of the variance in CES-T) scores for men (Table 5).

A further multiple regression for the male AS pa- tients was carried out with depression as the depen- dent variable and the measures of pain as the inde- pendent variables. Pain was found to explain 11.0% of the variance in CES-D scores for men compared to 46.3% for women (Table 6).

TABLE 3

Stepwise Multiple Regression Analysis on Depression for Women

~~

Percentage of Addition to Step variable variance percent fl in final

entered explained variance equation

M PQ 35.82 35.82 0.46" AS pain 46.31 10.49 0.35"

-

MR = 0.68. F = 19.41", df = 2.45. " P < 0.001. " P < 0.01.

Arthritis Care and Research Gender, Depression, and AS 49

TABLE 4

Correlation Matrix for Men

Variables

1 2 3 4 5 6 7 8 9 10

1 Depression 2 AS Pain 3 MPQ 4 Disability 5 IHLC 6 PHLC 7 CHLC 8 Social SE 9 Personal SE

10 Exercise

0.29" 0.28c8 0.42" -0.24" 0.17' 0.29" -0.16' -0.19' 0.16' 0.36" 0.52'' NS 0.22" NS NS NS NS

NS NS 0.25" NS NS NS NS NS 0.21" 0.29" NS NS NS

NS -0.26" NS NS NS NS NS NS 0.20'

NS NS NS 0.77" NS

NS

'f P : 0.01. ') P < 0.001.

P < 0.05. AS, ankylosing spondylitis; MPQ, McGill Pain Questionnaire; IHLC, internal health locus of control; PHLC, powerful others health locus of control; CIILC,

chance health locus of control; SE, self esteem; NS. not significant.

DISCUSSION

The preliminary investigation of psychological fac- tors in AS suggests that depression may be more prev- alent than is indicated by the widely held beliefs con- cerning the psychosocial nature of AS patients. The level of depression in the sample as a whole was found to be 3170, similar to that noted among physically dis- abled people, eg., 35% [24]. People with AS appear to have a risk ratio for developing depression com- parable to that of people with other forms of physical disability. In relation to gender, the results show that the prevalence of depression is significantly greater in female AS patients than male AS patients. Women were 1.8 times more likely to report being depressed than men, The ratio of depressed female to male AS

TABLE 5

Stepwise Multiple Regression Analysis on Depression for Men

70 of Step variable variance Addition to j3 in final

entered explained 70 variance equation .~

i3isatiility 15.63 15.63 0.34" MPQ 20.39 4.76 0.28" l<xerc:ise 24.96 4.57 0.22b 1 HLC: 28.60 3.63 -0.19,- Self-esteem (personal) 31.39 2.79 -0.17' --

" P .: 0.001. " P ': 0.01. ' P s: 0.05. MPQ, McCill pain questionnaire; IHLC, internal health locus of control

patients was found to be of exactly the same magnitude as thar found in epidemiologic surveys: 1.8 times great- er for women, albeit at greater absolute values. Al- though longitudinal studies are necessary to address issues of causality, the results suggest that the presence of AS may have a similar effect on depressive symp- tomatology for both men and women. In addition, the level of depression among women was found to be equivalent to that reported by women with other forms of arthritis. Therefore, the stereotyped view of the "typical" AS patients as being less depressed than other arthritis patient groups may not be accurate.

In addition to variation in prevalence rates, the de- terminants of depression were gender differentiated Pain was the only significant predictor of depression for women but was found to be of less importance for men. The gender differences in prevalence and de- terminants of depression cannot be explained by vari- ation in disease-related variables, measures of pain, or health behavior. The sample was found to be ho- mogen eous along these dimensions. Although levels of reported pain were similar, the influence of pain on psychological well-being differed by gender. A strong relationship between pain and depression was found for women, but only a moderate relationship was found for men. It may be that other empirical studies reporting a strong relationship between pain and depression were based on samples comprised mainly of women, e.g., the Kazis et al. study [8]. A difference in the sex ratio of samples may therefore contribute to inconsistent findings concerning the re- lationship between pain and depression. It should be noted ihat the high percentage of variance in depres-

511 Bm-low et al. Vol. 6, No. 1, March 1993

TABLE 6

Multiple Regression Analysis on Depression for Men Using Pain Measures

~ ~ ~~ _____ _____

% of tariance Addition to fl in final Variables explained % variance equation

AS pain 7.95 7.95 0.22“ bIPQ 1 3 .o 3.04 0.19’’

’/ P < 0.01. “ P < 0.05. ’ P < 0.001. AS, arikylosing spondyli tis; MPQ. McGill pain questionnaire.

s:lon explained by pain among the women may have been influenced by the relatively small number of women in the sample. The percentage of variance explained in outcomes for large samples tends to be smaller than that explained in small samples. The number of women in this survey reflects reported sex ratios and although relatively small, does greatly ex- ceed the recommended minimum of five times more cases than independent variables [25]. However, as pain was the only significant predictor of depression for women compared to a combination of five factors for men, it does seem likely that pain is an important influence on psychological well-being for women.

IMPLICATIONS

Health care professionals need to be aware that, despite the stereotyped view of the AS patient as being well-adjusted psychologically, people with AS may be susceptible to periods of psychological distress during the course of their disease. Indications of emotional distress are often ignored in patients with pre-existing physical disorders [26]. It may be necessary for health care professionals to give more consideration to psy- chological well-being in AS, particularly because women demonstrate increased vulnerability to de- pression. Additionally, the significant influence of pain on symptoms of depression in women suggests that improved control of pain, either by drug therapy or alternative methods such as exercise or relaxation, niay have the added benefit of improving psycholog- ical well-being.

The problems of detecting psychological distress are further complicated by the fact that patients tend to present depression in terms of somatic, rather than psychological symptoms [27]. Several of the most com- mon symptoms reported by depressed patients (e.g.. tiredness and backache [28] ) can also be indicative of AS. Thus, a health care practitioner may find it difficult

to distinguish between symptoms of AS and symptoms of depression. On a more positive note, depressive disorders detected by health professionals have a bet- ter outliook than those that remain undetecied [29]. Therefore, showing an awareness of the patient’s psy- chological distress and allowing time for discussion or free expression of feelings may help to improve the outlook for depression for many AS patients.

The emotional consequences of rheumatic diseases in general remain largely neglected [30]. The psycho- social aspects of living with AS have rarely been ad- dressed, despite the fact that this disease has a rela- tively early age of onset and patients have to cope with the problems of living with a painful form of arthritis for most of their adult lives. This preliminary inves- tigation of the psychosocial nature of people with AS has indicated the importance of pursuing further re- search in this area.

Cautionary Notes The results of this study must be viewed with cau-

tion due to several methodological difficulties. First, although the sex ratio found in this study reflects that reported in the literature (3 M:l F), the total number of womlen AS patients is relatively small, so the sta- bility of the findings needs to be replicated in larger samples. Second, much of the data relies on patient self-report measures. Further research may benefit from thle inclusion of objective measures of severity and disability although this may be difficult to put into practice due to the lack of recognized techniques for measuring clinical or functional status in AS patients [ZO] and the lack of appropriate objective measures of disease activity [31]. Finally, the study was of a cross- sectionid design and therefore longitudinal research is necessary before causal issues can be addressed.

CONCLUSIONS

These findings may have important practical im- plications for health care professionals. People with AS may be at risk of developing clinical depression during the course of their disease. Future research is needed to identify when episodes of depression are most likely to occur, e.g., during a flare, and also to determine effective methods of dealing with psycho- logical problems when they occur. In addition, women with AS are likely to present with a differential symp- tom profile to that commonly found in men: a com- bination of AS symptoms and depressive symptoma- tology. ]Health care professionals should be aware that women in particular may not fit the stereotype of the “typicall” AS patient.

firthritis Care and Research Gender, Depression, and AS 51

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