The prevalence of anxiety disorders in dermatology outpatients: A systematic review and meta‐analysis

Anxiety is common in those with medical conditions and has significant impacts on mental well‐being as well as physical health outcomes. While several systematic reviews have examined the prevalence of anxiety in specific dermatological conditions, no reviews have examined the prevalence across the entire dermatology outpatient setting. This systematic review aims to provide an overview to dermatologists of the prevalence of, and trends in, anxiety in their outpatient clinics. As such, prevalence of anxiety in dermatology outpatient clinics was examined, and variations across type of anxiety and dermatological conditions were assessed. A search of PubMed, Embase, Cochrane and PsycINFO was conducted for studies that assessed anxiety prevalence in dermatology outpatients, with the last search conducted on 7 September 2022. Results underwent title/abstract and full‐text screening, followed by data extraction. Studies of patients 16 years and older and representative of dermatology clinics were included. Risk of bias was assessed using Joanna Briggs Institute Critical Appraisal Checklist. Meta‐analysis was conducted using CMA software, and subgroup analysis was conducted on relevant variables. 5423 studies were identified, and 32 included, with a total n = 12,812 participants. Under the random effects model, prevalence was estimated at 26.7% (95%CI 22.4–31.4; 95%PI 9.7–55.4). Subgroup analysis revealed a higher prevalence among studies of psoriasis patients than general dermatology studies. Estimates of prevalence were higher when assessed via self‐report screening than diagnostic interview. Anxiety occurred frequently among dermatology outpatients, especially psoriasis outpatients, at a higher rate than common estimates of prevalence in the general population. Given the effect of anxiety on patient outcomes and well‐being, dermatologists are encouraged to consider how anxiety may impact patients in their clinic, and how they can best identify patients with anxiety and subsequently support them.

is seen in other reviews as well, with studies reporting anxiety disorder prevalence ranges such as anxiety disorders at 4.8%-10.9% 6 in the general population, or general anxiety disorder at 3.8%-25% 7 in primary care patients with both reviews reporting significant regional and demographic variation across the globe. However, no significant difference in anxiety prevalence was reported between developed and developing/emerging nations. 6 Rates of anxiety appear substantially higher in people with chronic physical health conditions. 4,7 This prevalence (and variability) is reflected in dermatology; for example, systematic reviews in specific dermatological conditions report prevalence ranges such as 7%-48% in psoriasis studies, 8 and 0%-49.6% in hyperhidrosis 9 or a pooled prevalence estimate of 11.8%-19.3% in patients with rosacea. 10 It is unsurprising that anxiety may significantly vary across health conditions in the dermatology setting, given the significant variations across conditions in severity and impact on patient quality of life.
Systematic reviews in the dermatology setting tend to focus on a specific condition. A recent systemic review examined dermatology patients more broadly; however, this review did not distinguish outpatient clinic patients from other patient groups (e.g. inpatients, primary care patients), did not synthesize prevalence statistics, and used a more general search strategy across all disease types that may miss some key dermatology papers. 11 The tendency to combine outpatient clinic settings with other populations is common. This may further contribute to the variability of results and reduces the validity of applying these findings to patients in dermatology outpatient clinics. There is currently no systematic review that examines the prevalence of anxiety disorders across the entire adult dermatology outpatient setting.
Just as anxiety disorders are commonly comorbid with physical health conditions, they are often comorbid with other mental health conditions. 12 Anxiety disorders, and their comorbidities, are substantially associated with poorer quality of life outcomes in medical patients. 1,2 Furthermore, they may also have a significant impact on the nature of patient presentations; for instance, health anxiety conditions show distinct patterns of excessive careseeking and care avoidant behaviours 3 that may affect the doctor's interaction with the patient and their ability to provide effective care. Different types of anxiety disorders may have different impacts on quality of life; some may be associated with impaired quality of life independently, while others may be dependent on interactions with other psychological comorbidities. 13 This review aims to examine the prevalence of anxiety in dermatology outpatients and examine trends in prevalence across types of dermatological conditions, and other trends/ variables. The review also aims to examine the interaction of anxiety and other patient demographics. In doing so, we seek to provide dermatologists and those working in dermatology a resource with which to understand the psychological needs of the patients in their clinics.

M ATER I A L S A N D M ETHODS
This review was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement 14 and was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021282416). PubMed, PsycINFO, Cochrane and EMBASE were searched, and the final search date was 7 September 2022 (see Appendix A).
This search was conducted as part of a review of anxiety across five common medical outpatient settings (including dermatology, cardiology, gastroenterology, endocrinology, respiratory medicine; for further details, see Appendix A). Due to the unexpected large volume of results (Figure 1), the research team determined that it would be more meaningful for each medical specialty to be reported separately, allowing for a more detailed analysis of results. The PROSPERO protocol was amended to reflect this change, and the required changes to screening and extraction as a result, prior to extraction.
Covidence systematic review software was used for screening and extraction procedures. Two reviewers independently screened titles and abstracts and completed full-text review. Data extraction and risk of bias quality assessment were conducted by both reviewers. Any conflicts were resolved by a third reviewer. The primary outcome was the prevalence of anxiety and anxiety symptoms as measured by anxiety rating scales or clinical diagnosis. Secondary outcomes investigated how prevalence of anxiety varied across diagnosis method, dermatological condition, and country of study. Studies were required to report either the prevalence or provide enough data to enable its calculation. Where fulltext papers were unavailable, authors were contacted. If no response was received in 2 weeks, the paper was excluded. The Joanna Briggs Institute Checklist for Prevalence Studies tool (JBI) 15 was used to assess the quality (risk of bias) of the identified studies. This critical appraisal tool consists of nine questions and the scoring system is: 'yes' scores 1, 'no' or 'not clear' or 'not applicable' score 0. Therefore, lower scores indicate higher risk of bias.
Meta-analyses were conducted using Comprehensive Meta Analysis version 4.0 (CMA 4). 16 The proportion of variance was assessed using τ 2 test and I 2 statistics. Potential sources of heterogeneity were explored using random-effect subgroup analyses. The impact of publication bias was assessed via funnel plot and Egger's regression intercept. 17

Studies included
Our search strategy identified 5423 studies ( Figure 1). Thirty-two studies met the dermatology outpatient inclusion criteria, with a total n = 12,812 participants. Nine of the studies achieved the maximum JBI score of 9, 18 scored 8, 2 scored 7, and 3 scored 6, meaning all 32 studies met the JBI quality assessment requirements for inclusion. These included cross-sectional studies (n = 19), prevalence studies (n = 10) and case-control studies (n = 3). Study participants were recruited from hospital dermatology outpatient clinics and the sample sizes across studies ranged from n = 16 to n = 3519. Most (n = 11) of the studies were conducted in Europe; others were undertaken in the Middle East (n = 4), Asia (n = 6), South America (n = 3), North America (n = 3) and Africa (n = 3). One multi-centre study 18 combined data from 13 countries across Europe, including data from Russia and Turkey, and one study combined data from clinics in Canada and China. 19 Studies used self-report measures (n = 22), diagnostic interviews (n = 8) and patient records (n = 2) to assess anxiety. Papers reported the prevalence of overall anxiety symptoms/diagnoses (n = 24), obsessive-compulsive disorder (n = 8), general anxiety disorder (n = 5), panic disorder (n = 3), social anxiety/phobia (n = 2), agoraphobia (n = 2), illness anxiety disorder (n = 1), somatisation (n = 1) and post-traumatic stress disorder (n = 1). Prevalence of anxiety was investigated in the general dermatology outpatient population (n = 16), psoriasis patients (n = 9) and patients with other specific dermatological conditions (n = 7). The full study characteristics are summarized in Table 1. Two studies were excluded from the meta-analysis as they specifically examined only female 20 or geriatric 21 outpatients. Another study was identified as an outlier due to the reported prevalence of 100% 22 and was also excluded from the meta-analysis.

Overall prevalence of anxiety
Across the 29 studies included in the meta-analysis, prevalence of anxiety or anxiety symptoms varied substantially from study to study with a range of 2.9%-67.8%. Under the random effects model, the overall prevalence estimates of anxiety/anxiety symptoms reported by the 29 studies produced a mean prevalence estimate of 26.7% (95%CI (confidence interval) 22.4-31.4; 95%PI (prediction interval) 9.6-55.4), with significant between-study heterogeneity (p < 0.001, τ 2 = 0.343, I 2 = 96.0%; Figure 2a). Symmetry in the funnel plot ( Figure 2b) and Egger's test 17 (p > 0.05) indicated no publication bias present in the meta-analysis. Subgroup analyses by diagnosis method, dermatological condition and country were conducted to explore the potential heterogeneity between studies.   Studies where sample size is different to that reported in the abstract due to missing data, prevalence taken from subgroups or miscalculation within the paper. b Studies that reported overall prevalence that included specific other types of anxiety. In such cases we have extracted only the prevalence of anxiety symptoms/disorder or generalized anxiety symptoms/disorder.

Anxiety prevalence by method of identification
A significant difference in the prevalence of anxiety was detected in subgroups diagnosed with anxiety using different methods (p = 0.004). Screening studies assessing anxiety with the anxiety subscale of the hospital anxiety and depression scale (HADS-A; n = 15), 23 Figure 3a). There was not significant data to run subgroup analyses examining types of anxiety.

Anxiety prevalence by dermatological condition
It was intended that a subgroup analysis would be run to examine the prevalence of anxiety across different  dermatological conditions. However, psoriasis was the only condition for which there was adequate sample size to run such an analysis. A subgroup analysis therefore examined differences in prevalence in psoriasis patients, compared to patients in a general dermatology setting, and to other specific conditions. Prevalence of anxiety/anxiety symptoms was higher in studies of psoriasis outpatients (n = 9) 33.9% (95%CI 28.8-39.5; 95%PI 18.6-53.6; I 2 = 83.0%), followed by general dermatology outpatients (n = 14) 27.0% (95%CI 20.8-34.2; 95%PI 8.6-59.1; I 2 = 97.0). Anxiety occurred at the lowest rates in studies of other specific dermatology outpatients (n = 6) 15.1% (95%CI 7.2-28.8; 95%PI 0.9-76.8; I 2 = 96.6). The prevalence of anxiety was significantly different between these three dermatology outpatient conditions (p = 0.026; Figure 3b).

Anxiety prevalence by grouped countries
In the country subgroup analysis, countries were categorized as either developed or developing based on the United Nations Human Development Index. 25 Two studies were not included in this analysis as they provided data from multiple countries but did not provide prevalence rates for each country. There was no significant difference (p = 0.547) in the prevalence estimates of anxiety in developed (n =  Figure 3c).

DISCUS SION
Psychodermatology 'focuses on the intersection between skin and mental health' 26 and is an area of interest within dermatology. This is the first systematic review to assess the prevalence of all types of anxiety in the dermatology outpatient setting. While there was substantial variability in the prevalence of anxiety across studies, the meta-analysis revealed an average rate of anxiety in dermatology outpatients of 26.7%. This falls within the range of prevalence reported in some previous studies of single dermatological conditions (psoriasis; primary hyperhidrosis) 8,9 although not all (rosacea), which reported a lower prevalence than the present study. 10 Not enough studies in rosacea patients were found to examine whether subgroup data would be more consistent with this literature. As expected, the prevalence of anxiety in dermatology outpatients is substantially higher than estimates of anxiety disorders in the general population (e.g. 4.8%-10.9% in one systematic review, 6 and 3.8% pre-COVID and 4.8% post-COVID in another). 5 This is in line with findings that rates of anxiety are significantly higher in those with chronic health conditions compared to general populations. 4 The results of the first subgroup analysis, found substantially higher prevalence rates among studies that used a validated screening tool (e.g. hospital anxiety and depression scale, anxiety subscale; HADS-A; 34.3%) when compared to those using clinical diagnosis (14.8%). Given that clinical diagnosis is considered the gold-standard diagnostic approach, these findings indicate that self-assessment may overestimate anxiety prevalence. The tendency for self-report to overestimate anxiety rates relative to clinical diagnosis has been previously reported in other literature, 10 and is consistent with similar findings in depression assessment. 27 It was found that the prevalence of anxiety in psoriasis patients (33.9%) was generally higher than anxiety in general dermatology clinic studies (27.0%). Studies into other specific dermatological conditions appear to reveal lower prevalence estimates (15.1%). It is possible that the prevalence in the general dermatology clinic is increased by the presence of psoriasis patients within this setting; however, further primary research breaking down anxiety across condition types would be necessary to examine this further. Our prevalence rate for anxiety in psoriasis is in the higher end of the range presented by Fleming et al. in 2017 of 7%-48%. Their systematic review presented a more heterogeneous group of studies on psoriasis across many settings.
No significant difference was found in prevalence in developed countries compared to developing countries. However, much less data were available on developing countries compared to developed (nine studies, compared to 19). No reviews comparing anxiety prevalence in dermatology patients in developing and developed nations could be identified. A prior systematic review of prevalence in rosacea suggested that there may be continental variability (across Europe, Asia and North America), but was unable to make conclusions of significance due to sample size. 10 A study of anxiety in the general population indicated that there was no significant difference in anxiety between developed and developing/emerging nations. 6 However, given the difference in target population and in the classification system used, direct comparisons cannot be made. Ultimately, there is still much to be understood about the relationship between prevalence of anxiety in dermatology patients and international socioeconomic status.
While this review examined a range of anxiety types in the dermatology setting, most identified literature focused on prevalence of either anxiety disorder as a broader concept, or specifically on general anxiety disorder. It appears that there may be trends across types of anxiety, however, further primary studies performing an assessment across anxiety types are needed. For now, dermatologists should keep in mind that anxiety is relatively common in dermatology patients, and that anxiety may take a range of forms.

Clinical
Dermatologists, and their patients, will benefit clinically from seeing robust evidence demonstrating the presence of elevated rates of anxiety in the dermatology outpatient setting. Anxiety can have significant comorbidities with other mental health conditions, such as depression. 12 Further, poorer mental health outcomes correlate with worse physical health outcomes and may be associated with exacerbations of health problems, 28,29 including in dermatology, 30 and worse overall quality of life outcomes. 1,2 In some cases there may be a bidirectional effect between mental health issues and disease severity in dermatology patients. 10 It is important to note that anxiety disorders are treatable conditions, with a number of effective treatment options including psychotherapy and pharmacotherapy available, such as cognitive behavioural therapy (CBT), selective serotonin reuptake inhibitors or combination CBT/drug therapies. 31 Thus, addressing anxiety and referring to appropriate psychosocial care has not only benefits for the mental health outcomes of the patients, but may also help improve outcomes of their dermatological conditions.
Despite the prevalence of anxiety, and its impact on quality of life and health outcomes, doctors may not always be able to identify it in their patients. Anxiety disorders are often underdiagnosed and undertreated across a range of clinical settings. [32][33][34] A systematic review of the use of consultation liaison psychiatry in the hospital setting found a trend of under-referral for mental health matters relative to the prevalence of mental illness, and suggested that improved education may reduce this gap. 35 Hence, these findings indicate value in improved screening for, and assessment of, anxiety disorders in the dermatology setting, and of select patient subgroups. Thereafter, referral for the parallel management of clinical range anxiety can occur depending on the needs of the patients and resources of the clinic.

Research
It was noted that significant weaknesses or omissions existed in the research methodology and reporting of several papers screened in this study. The most common problems were (a) failure to report actual prevalence of anxiety (i.e. studies provided only mean anxiety scores), (b) unclear calculations, (c) lack of clarity, or failure to report, of exclusion criteria and (d) omission of the reported response rate. This led to a large number of studies being excluded that may otherwise have been eligible.
For studies included, these issues caused problems in determining the validity and generalisability of findings, as well as in conducting subgroup analyses. For instance, studies with a low response rate have a much higher risk of bias. The team addressed this by excluding studies reporting lower than 70% response rate; however, some studies could not be excluded based on this as this was not reported, and researchers had to judge whether a study was likely to have sampled appropriately. While the included studies all scored adequately on the JBI, 17 studies were marked down on one or more domains; 11 did not report response rate, 10 did not describe the subject and setting in detail, one did not clearly outline sampling and one did not clearly outline whether the condition was measured in a standard, reliable way. Further, such matters led to the team contacting authors and re-checking calculations. When publishing, researchers may wish to consider these common issues to strengthen both their studies and future systematic reviews.

Limitations
While this review has yielded informative results relevant to clinical practice results, the ability to conduct subgroup analysis was hindered by the relatively few number of studies that appropriately assessed anxiety prevalence in dermatology outpatients. For instance, while psoriasis was found to be associated with higher rates of anxiety than other dermatological conditions, we were unable to examine variations across other conditions. The analysis of anxiety across dermatological conditions would also be aided by primary research if future studies in the general dermatology clinic provided a breakdown of prevalence across condition.
Similarly, a key area of interest was variation over time, especially given the COVID-19 pandemic and the effect that this may have on anxiety; however, such an analysis could not be run. Further data would also enable a comparison of anxiety rates as determined by self-report tools other than HADS-A. While it was found that self-report studies tend to report a higher prevalence than diagnostic interview studies, 10 more research is needed to examine this across specific self-report tools in the dermatology setting. The above analyses would all benefit from further primary studies. As such, these may be of value to re-visit in the future when more results are available.
Variation in measurement tools have been analysed and reported where possible. However, in some cases this could not be done. It should be noted that the HADS was not always applied consistently, with some papers using different cut-off points than the standard ≥8. The research team standardized this where possible, but this could not be done on four papers. On further analysis (data not reported here), prevalence was higher when other papers using higher cutoffs than standard (e.g. HADS-A ≥ 10) were removed, from 34.3% (95%CI 27.7-41.6) to 37.5% (95%CI 31. 8-43.6). This has been controlled where possible but may have some impact on the variation. In addition, this review was not able to control for variations in sensitivity and selectivity across other self-report tools, as mentioned above, and could not assess variations in outcomes across different language variations of the HADS. Further data would be needed to perform such analysis.

CONCLUSION
This systematic review found that patients in the dermatology outpatient setting have a high prevalence of anxiety, approximately 26.7%. Prevalence was significantly higher in patients with psoriasis when compared with the general dermatology outpatient population. Substantial variation in prevalence estimates were found; notably, a high proportion of this came from method of assessment, with prevalence estimates from a validated screening tool (HADS-A) being significantly higher than those from diagnostic interview. Further research is needed to better elucidate how anxiety rates vary across types of dermatology condition and types of anxiety. Given that anxiety has significant impacts on both mental and physical well-being, dermatologists and those working in the dermatology setting may wish to consider how they can best identify those with anxiety and support these patients.

AC K NOW L E D G M E N T S
The authors would like to thank Jessica Strudwick for her help consulting on this systematic review. Open access publishing facilitated by University of New South Wales, as part of the Wiley -University of New South Wales agreement via the Council of Australian University Librarians.

F U N DI NG I N FOR M AT ION
Mindgardens Neuroscience Network.

C ON F L IC T OF I N T E R E S T S TAT E M E N T
The authors have no conflict of interest to declare.

DATA AVA I L A BI L I T Y S TAT E M E N T
The data that support these findings are available from the corresponding author (J. Newby) upon reasonable request.

E T H IC A L A PPROVA L
This study did not require ethics approval.