Prevalence of Neuropathic Pain and Related Characteristics in Hidradenitis Suppurativa: A Cross-Sectional Study

Burden of Hidradenitis Suppurativa: A Systematic Literature Review of Patient Reported Outcomes

INTRODUCTION

Hidradenitis suppurativa (HS) has a profound negative impact on patients' health-related quality of life (HRQoL). Here we summarize the evidence on HRQoL and Patient Reported Outcomes (PROs) in patients with HS in real-world settings by conducting a systematic literature review (SLR) of observational studies.

METHODS

Data sources included MEDLINE, Embase & PsycINFO between January 1, 2010 and August 29, 2021, and conference proceedings between 2019 and 2021. Identified abstracts were reviewed and screened independently by two reviewers. Eligibility criteria included patients with HS of any severity, sample size ≥ 100, reporting PROs including HRQoL measures. Included studies were critically appraised.

RESULTS

Fifty-eight observational studies matched inclusion criteria. Dermatology Life Quality Index (DLQI) was the most commonly utilized instrument: 57% of included studies reported mean baseline DLQI scores, ranging between 8.4 and 16.9, indicating a very large impact on the patients' HRQoL. Higher scores were reported with increasing disease severity and among female patients. Pain was assessed mostly by an 11-point (0-10) numeric rating scale (NRS) with a mean baseline score ranging from 3.6 to 7.7 indicating moderate to high pain levels. There was a negative impact of HS on patients' psychological well-being, based on PRO scores related to depression and anxiety. A high proportion of sexual dysfunction was reported, with a larger impact on women than men. Work productivity and leisure activity were consistently found to be impaired in patients with HS.

CONCLUSIONS

All included studies reported a negative impact of HS on patients' lives. A diverse set of disease- and non-disease-specific PRO instruments were utilized highlighting the need for more consistent use of HS-specific validated PRO instruments to assess the impact of HS on the different aspects of patients' HRQoL to allow for data to be more meaningfully interpreted and compared in real-world settings. Patients with HS need better disease management approaches that address the observed low quality of life.

Quantitative Sensory Testing to Characterize Sensory Changes in Hidradenitis Suppurativa Skin Lesions

Importance

Pain is the most impactful symptom in patients with hidradenitis suppurativa (HS). Characterization of sensory profiles may improve understanding of pain mechanisms in HS and facilitate identification of effective pain management strategies.

Objective

To characterize somatosensory profiles in patients with HS at clinically affected and nonaffected sites compared with pain-free reference data.

Design, Setting, and Participants

This cross-sectional study was conducted at the Emory University Dermatology Clinic. It was hypothesized (1) that patients with HS would demonstrate hypersensitivity to pain in HS lesions and (2) that some patients would have sensory profiles consistent with complex pain mechanisms. Therefore, adults with dermatologist-diagnosed HS and at least 1 painful HS lesion at the time of testing were enrolled between September 10, 2020, and March 21, 2022. Patients with other diagnoses contributing to pain or neuropathy were excluded. Data analysis was conducted between March and April 2022.

Exposure

Quantitative sensory testing was performed on HS lesions and control skin according to a standardized protocol.

Main Outcomes and Measures

Quantitative sensory testing outcomes included innocuous thermal and mechanical sensitivity (cold, warmth, and light touch detection thresholds), noxious thermal and mechanical sensitivity (cold, heat, pinprick, and deep pressure pain thresholds and suprathreshold pinprick sensitivity), temporal summation of pinprick, paradoxical thermal sensations, and dynamic mechanical allodynia (pain upon light stroking of the skin). Sensitivity in HS lesions was compared with sensitivity in a control location (the hand) and in pain-free controls using t tests.

Results

This study included 20 participants with a median age of 35.5 (IQR, 30.0-46.5) years, the majority of whom were women (15 [75%]). In terms of race and ethnicity, 2 participants (10%) self-identified as Asian, 11 (55%) as Black, 6 (30%) as White, and 1 (5%) as more than 1 race or ethnicity. Compared with site-specific reference values from healthy, pain-free control participants, HS lesions were insensitive to innocuous cold and warmth, noxious heat, and light touch (t = -5.69, -10.20, -3.84, and 4.46, respectively; all P < .001). In contrast, HS lesions also demonstrated significant hypersensitivity to deep pressure pain (t = 8.36; P < .001) and cutaneous pinprick (t = 2.07; P = .046). Hypersensitivity to deep pressure pain was also observed in the control site (t = 5.85; P < .001). A subset of patients with HS displayed changes in pain processing that are often seen in neuropathic and nociplastic pain conditions, including hypersensitivity to repetitive pinprick (5 [26%]), paradoxical thermal sensations (3 [15%]), and pain upon light stroking of the skin (10 [50%]).

Conclusions and Relevance

The findings of this cross-sectional study suggest that HS involves local changes in the skin or its free nerve endings, possibly leading to peripheral neuropathy and alterations in the transduction of innocuous and noxious thermal and mechanical stimuli. For some patients, central nervous system changes in somatosensory processing may also occur, but confirmatory evidence is needed. Better understanding of neuropathic and nociplastic mechanisms in HS pain could lead to individually tailored treatments.

Correlation between PainDETECT Questionnaire and Quantitative Sensory Testing for the Detection of Neuropathic Pain in Hidradenitis Suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease that is often severely painful due to nociceptive mechanisms (i.e., stimulation of cutaneous nociceptors). However, patient-reported pain character suggests that neuropathy may also drive HS pain in a subset of patients. Quantitative sensory testing (QST) can help identify neuropathic pain by testing for heightened and paradoxical pain responses in patients, but it is less feasible for routine clinical use compared with brief questionnaires. We therefore tested the suitability of a standardized neuropathic questionnaire (PainDETECT; PD-Q) for use as a surrogate clinical measure by directly comparing it with QST-identified neuropathic pain in HS.

METHODS

This observational, cross-sectional study included 22 adults with painful HS lesions who completed the PD-Q and underwent QST. A receiver operating characteristic curve was generated and Cohen's Kappa, sensitivity, and specificity were examined at three scoring thresholds.

RESULTS

Of the 22 participants, 14 (64%) exhibited dynamic mechanical allodynia and/or paradoxical thermal sensations in QST, which are characteristically found in neuropathic pain. According to the PD-Q, 8 participants (36%) were unlikely, 8 (36%) were possible, and 6 (27%) were likely to have neuropathic pain. A PD-Q Score indicating possible or likely neuropathic pain (i.e., ≥13) demonstrated 82% agreement with QST-determined neuropathic pain (Cohen's Kappa = 0.61 [p = 0.004]; sensitivity = 86%; specificity = 75%).

CONCLUSION

The PD-Q demonstrates moderate agreement with QST in screening for neuropathic pain in HS and may be a helpful clinical tool.

Can chronic spontaneous urticarial produce symptoms of neuropathic pain?

BACKGROUND

Chronic spontaneous urticaria (CSU) is a condition that is associated with recurrent pruritic hives and/or angioedema lasting for more than 6 weeks and is known to affect 1% of the population. Neuropathic pain can be defined as abnormal pain in the peripheral or central nervous system following injury and results from dysfunctions in the peripheral or central nervous system without peripheral nociceptor stimulation. Histamine appears in the pathogenesis of both the CSU and diseases of the neuropathic pain spectrum.

OBJECTIVE

To evaluate the symptoms of neuropathic pain in patients with CSU using scales.

METHOD

Fifty-one patients with CSU and 47 sex- and age-matched healthy controls were included in the study.

RESULTS

The results of the short-form McGill Pain Questionnaire revealed the scores in the sensory and affective domains, Visual Analogue Scale (VAS) scores and pain indices to be significantly higher in the patient group (p < 0.05 for all cases), while the overall pain assessment and sensory assessment based on the Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) pain scale were also significantly higher in the patient group. Based on the assumption that scores of > 12 indicated neuropathy, 27 (53%) of the patients in the patient group and 8 (17%) in the control group were found to have neuropathy (p < 0.05).

STUDY LIMITATIONS

Cross-sectional study, small patient sample and use of self-reported scales.

CONCLUSION

In addition to itching, patients with CSU should be aware of the potential for the association of neuropathic pain. In this chronic disease that is known to affect the quality of life, using an integrated approach with the patients and identifying accompanying problems are as important as treating the dermatological disorder.

The impact of hidradenitis suppurativa on professional life

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory disease that affects intertriginous skin.

OBJECTIVES

To determine the extent of work ability and productivity impairment as a result of HS in Germany.

METHODS

A prospective, multicentre, epidemiological, noninterventional study of patients with HS was conducted. Medical history, medical examination performed by dermatologists and patient-reported outcomes [Work Ability Index (WAI) and Work Productivity and Activity Impairment (WPAI)] were collected.

RESULTS

Of the 481 patients with HS included in the study, 99% were below the current statutory retirement age. In total, 53·3% of patients were working full time, 16·8% part time and 7·3% had retired. The unemployment rate was 12·6%, two times higher than in the general German population. Medical leave because of HS, within the last 6 months, was reported in 41·4% [95% confidence interval (CI) 36·9-46·0], with a duration of 39·3 days on average (95% CI 32·4-46·1). The mean HS-related WPAI absenteeism was 13.3% (95% CI 9·7-16·8), and the loss in productivity because of HS during working hours (WPAI presenteeism) was 25.2% (95% CI 21·8-28·6). Presenteeism was associated with HS disease severity. Overall work impairment because of HS was 33·4% (95% CI 29·3-37·6). The WAI score for patients was 32·2, ∼20% lower than for the average German employee. Only 62·8% of patients were relatively certain that they would be able to perform their work in the coming 2 years. Being more depressed and having more severe pain were associated with lower work ability and overall work impairment. The estimated annual loss of gross value added because of HS for Germany was ∼€12.6 billion (€3.3 billion related to a lower employment rate, €3.5 billion related to absenteeism and €5.8 billion related to presenteeism).

CONCLUSIONS

HS leads to a substantial decrease in work ability and productivity and considerable loss of gross value added. Impairment during working hours correlates with disease severity, underlining the socioeconomic importance of early and adequate treatment. Furthermore, decreased work ability and productivity is linked to depressed mood and severe pain, aspects that need more attention in patient care.

Pain experiences among those living with hidradenitis suppurativa: a qualitative study

BACKGROUND

Pain is rated by patients with hidradenitis suppurativa (HS) as the disease's most impactful symptom. HS therapies are often insufficient to control inflammatory disease activity and pain. A better understanding of patient experiences with pain may improve patient-provider relationships and help identify strategies for addressing HS pain.

OBJECTIVES

This qualitative study sought to characterize lived pain experiences of those with HS.

METHODS

English-speaking patients ≥ 18 years old with a dermatologist-confirmed diagnosis of HS and an average numerical rating scale pain score of ≥ 1 over the preceding week were recruited from a single academic medical centre in Atlanta, Georgia, USA. Semistructured interviews were conducted from November 2019 to March 2020 to explore participants' HS pain experiences and the subsequent impact on their lives. Thematic saturation was reached after interviewing 21 participants. Interviews were audio recorded, transcribed, and analysed using thematic analysis.

RESULTS

Among 21 study participants, the median 7-day average pain score was 6 (interquartile range 3-7; scale ranges from 0 to 10, with 10 being most pain). Participants' descriptions of pain were consistent with nociceptive pain, neuropathic pain and itch. Pain impacted multiple life domains, including physical limitations (decreased mobility and impaired sleep), decreased psychological wellbeing (irritability, depression, loss of control, and difficulty communicating pain experiences) and impaired social relationships (social isolation, intimacy problems and difficulty fulfilling social responsibilities). Although participants reported chronic discomfort, acutely painful and unpredictable HS disease flares caused more distress and quality-of-life (QoL) burden. Participants frequently treated their pain without input from the medical team, sometimes with unsafe medication doses or combinations. Factors contributing to self-management of pain included difficulty accessing timely outpatient care during disease flares and fear of stigma from healthcare providers.

CONCLUSIONS

When present, HS-related pain may impact not only physical wellbeing but also mental health and relationships. In addition to therapies that target the inflammatory disease burden, treating the symptom of pain may improve patients' QoL and wellbeing. Because patients with HS have difficulty explaining their pain, proactively asking them about pain may identify unmet needs, facilitate better pain control and improve QoL. Further, the influence of HS-related pain on numerous aspects of QoL suggests the need for multidisciplinary, patient-centred approaches to HS pain management.

A Practical Guide for Primary Care Providers on Timely Diagnosis and Comprehensive Care Strategies for Hidradenitis Suppurativa

Hidradenitis suppurativa is a chronic, progressive inflammatory disease of the skin with many systemic implications. Hidradenitis suppurativa is frequently underdiagnosed or misdiagnosed, particularly because of heterogeneity in presentation and low disease recognition. Patients can see multiple types of health care providers, including primary care providers, along their journey to an accurate diagnosis. This review provides a comprehensive overview of the clinical presentation, associated comorbidities, and life impact associated with hidradenitis suppurativa. Disease features described here can facilitate earlier identification of hidradenitis suppurativa, differentiation from common mimickers, and timely referrals for multidisciplinary management when needed. Engagement of the medical community will also support comprehensive care strategies necessary in hidradenitis suppurativa.

Pain measurement in painful skin conditions and rheumatoid arthritis randomized controlled trials: a scoping review to inform pain measurement in hidradenitis suppurativa

BACKGROUND

Pain is the most common and bothersome symptom experienced by people with hidradenitis suppurativa (HS) and has been prioritized as an outcome domain by the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC).

OBJECTIVES

To perform a scoping review of pain measurement in randomized control trials (RCTs) of painful skin conditions (PSCs) and use of the pain numerical rating scale (NRS) and visual analogue scale (VAS) in rheumatoid arthritis RCTs, to inform the efforts of HISTORIC to reach consensus on how to measure pain intensity in HS trials.

METHODS

A search was conducted on several publication databases. Inclusion criteria were RCTs with a minimum of 10 participants that measured pain intensity.

RESULTS

Pain NRS and VAS were used in 68% of PSC trials. Respectively, 77% and 87% of PSC and rheumatoid arthritis RCTs did not specify the recall window. The commonest recall window in PSCs when specified was 24 h. In total, 33% of PSC trials assessed maximum pain intensity and 3% average pain intensity, while 87% of rheumatoid arthritis trials did not provide details. Pain data were reported as mean difference by 76% of PSC trials and 75% of rheumatoid arthritis trials. Respectively, 10% and 11% of PSC and rheumatoid arthritis studies reported pain as the percentage of patients reaching a desirable state and only 1% and 2% reported number needed to treat.

CONCLUSIONS

While pain NRS and VAS are standard methods to measure pain intensity in PSCs, key details such as the recall window are often omitted and there is no consensus on how to report pain NRS data. What is already known about this topic? Pain is the most burdensome symptom experienced by patients with hidradenitis suppurativa and has been prioritized as an outcome domain by the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). What does this study add? Our review shows substantial variation in how pain numerical rating scale (NRS) and visual analogue scale are utilized in clinical trials. This variation restricts meta-analysis of pain intensity results. There is a need for consensus regarding the recall window for pain NRS and maximum vs. average pain, and whether current pain should be measured.

Dermatological Conditions Inducing Acute and Chronic Pain

Pain is a common condition in dermatology. The aim of this review is to analyse the characteristics of pain in dermatology. Some skin diseases are conventionally known to cause pain; e.g. ulcers, pyoderma gangrenosum and herpes zoster. Common dermatoses, such as psoriasis or atopic dermatitis, can also cause significant pain. Some conditions are characterized by neuropathic pain and/or pruritus, without visible primary lesions: e.g. the neurocutaneous diseases, including small fibre neuropathies. Patients often fear pain in skin surgery; however, surgical procedures are rather well tolerated and any pain is mainly due to administration of local anaesthetic. Some therapies may also be uncomfortable for the patient, such as photodynamic therapy or aesthetic procedures. Thus, pain in dermatology is common, and its aetiology and characteristics are very varied. Knowledge of the different situations that cause pain will enable dermatologists to propose suitable analgesic solutions.

New treatments and new assessment instruments for hidradenitis suppurativa

Research interest in Hidradenitis Suppurativa (HS) has grown exponentially over the past decades. Several groups have worked to develop novel scores that address the drawbacks of existing investigator assessed and patient reported outcome measures currently used in HS trials, clinical practice and research. In clinical trial settings, the drawbacks of the HiSCR have become apparent; mainly it's lack of a dynamic measurement of draining tunnels. The newly developed (dichotomous) IHS4 and HASI-R are backed up by adequate validation data and are good contenders to become the new primary outcome measure in HS clinical trials. Patient reported outcomes, as well as physician reported measures, are being developed by the HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). For example, the Hidradenitis Suppurativa Quality of Life (HiSQOL) score is a validated measure of HS-specific quality of life and is already being used in many HS trials. Magnitude of pain measurement via a 0-10 numerical rating scale is well-established, however consensus is still required to ensure consistent administration and interpretation of the instrument. A longitudinal measurement over multiple days rather than at one time point, such as for example the Pain Index could provide increased reliability and reduced recall bias. Ultimately, these newly developed scores and tools can be included in a standardized registry to be used in routine clinical practice.