Clinical Report

Accepted Jul 4, 2016; Epub ahead of print Jul 5, 2016

Acta Derm Venereol 2017; 97: XX–XX.

Corr: Eveline Bijlard, Department of Plastic and Reconstructive Surgery, Faculty building EE-1591, P.O. Box 2040, NL-3000 CA Rotterdam, The Netherlands. E-mail: e.bijlard@erasmusmc.nl

Keloids are abnormal scars, which act like benign tumours growing beyond the margins of the original wound (1). Additional physical symptoms, such as itch and pain, occur in up to 80% of patients (1, 2). Keloid disease can lead to aesthetic, physical and psychological complaints in affected individuals (3, 4). Treatment has varying results and is associated with a high degree of resistance to treatment and recurrence (5).

The advent of health-related quality of life (HRQL) measures has greatly improved our insight into the burden of skin diseases. Skin diseases (e.g. psoriasis) may negatively affect HRQL to a degree comparable to or exceeding that of life-threatening illnesses, such as myocardial infarction and heart failure (6). Thus, the impact of skin diseases should not be underestimated, and HRQL research is warranted for all skin conditions.

The limited research available on HRQL of patients with scars shows negative effects on physical, psychological and social well-being (3, 4, 7–9). These studies, however, have substantial limitations, most importantly, a failure to differentiate between hypertrophic scars (HTS) and keloids, while these conditions are distinct-ly different from one another. HTS stay within the original wound margins, are self-limiting, and respond considerably better to treatment with lower recurrence rates (10). Preservation of HRQL is more likely with favourable symptoms, prognosis and duration of HTS compared with keloids. Research on these 2 conditions combined probably underestimates the burden of the more severe condition, keloid disease. In addition, none of these studies evaluated the effect of keloids on HRQL using both disease-specific and generic health measures. Generic health measures allow comparison of the burden of keloids with that of other major diseases. Thus, the degree of burden of keloids can be illustrated and the need for effective treatment can be formally prioritized. The combined use of different HRQL instruments provides such a broad and sensitive assessment of the burden of skin diseases (11).

Previously we reported on Skindex-29 scores in our population, showing an association of keloid disease and worse HRQL, in which emotional HRQL was severely impaired in 48% of patients (12). Similar outcomes were seen on a generic utility score (EQ-5D-5L), with a drop of 8% in utility for keloid patients (12). In the current paper we provide further details on the effect of keloid disease with the most widely used generic HRQL measure (SF-36), and on which factors are indicators of HRQL impairment. Thus, the current study aimed: (i) to determine the HRQL of patients with keloid disease; and (ii) to identify indicators of high disease burden.

The present study was a multi-centre cross-sectional online survey.

All adults diagnosed with keloid disease by an experienced physician from the participating Departments of Plastic and Reconstructive Surgery and Dermatology at 2 university hospitals were eligible. Diagnosis of keloid disease was made on clinical presentation, most important continuous growth, beyond wound borders, without spontaneous regression after one year. Patients were excluded if there was any doubt about the diagnosis, or if the diagnosis differed between physicians. Patients, who were not proficient in Dutch, no longer had a keloid, or had additional skin diseases, were excluded. All respondents completed an online informed consent form and a series of self-administered questionnaires between February and May 2014. Non-responders were contacted by telephone after 3 weeks to invite them to participate.

Patient and Observer Scar Assessment Scale (POSAS). Scar severity was subjectively assessed using the patient scale of this validated scar assessment tool (PSAS), consisting of 6 items on pain, itch, colour, stiffness, thickness, and irregularity, as well as an overall opinion on the scar. All items as well as overall opinion were rated on a 10-point scale (13). Higher scores represent a more severe scar. A threshold of >3 on the pain and itch items was used to indicate substantial symptoms (14, 15).

SF-36. This widely used generic HRQL questionnaire contains 36 questions that provide scores on 8 different dimensions of functional health and well-being. Scores are given on a 100-point scale, with higher scores indicating better quality of life. Norm-based physical component summary scores (PCS) and mental component summary scores (MCS) (mean 50, SD 10) were calculated using pooled-age-matched norm scores from a Dutch urban (Amsterdam) reference population (16).

Besides the above-mentioned questionnaires, the Skindex-29 (17, 18) and EQ-5D-5L (19) were also used. These results have been reported previously (12).

Socio-demographic and clinical characteristics, including sex, age, skin colour as described by Fitzpatrick, location and visibility of the keloid, number of keloids (quantity), disease duration, origin of the keloid, previous treatments, and comorbidities, were collected.

Characteristics of the study population were analysed using descriptive statistics. Cohen’s d effect sizes were calculated; values > 0.20 were considered small effects, > 0.50 medium effects, and > 0.80 large effects (20).

Correlations were calculated between the independent variables and the 4 Skindex-29 scales, the SF-36 PCS and MCS scales, and EQ-5D-5L index scale. Previously-reported data from Skindex-29 and EQ-5D-5L instruments were also used to improve the validity of the correlation and regression analysis.

Pearson’s correlation coefficients (r_p) were calculated for normally distributed data, and Spearman’s correlation coefficients (r_s) for not normally distributed data.

Seven multiple linear regression models were made to assess the predictive value of the independent variables (sex, age, visibility of the keloid, number of keloids as well as all the PSAS variables: pain, itch, colour, stiffness, thickness, and irregularity) on HRQL outcomes. Non-normal dependent variables were root-transformed in order to obtain a normal distribution. Data were entered, followed by a backward procedure, in which non-significant effects (p > 0.10) were removed from the models. Regression coefficients were standardized (betas) to allow for better comparison of different factors in the model, independent of the units of measurement of the variables. A beta of 0.1 indicates a small effect, 0.3 a medium effect, and 0.5 a large effect. R² represents the amount of variability in the outcome that is accounted for by indicators used in the model.

All analyses were executed using IBM^® SPSS Statistics version 22 for Mac OSX. Two-sided p-values ≤ 0.05 were regarded as statistically significant.

The Ethics Board Committees of both participating academic hospitals concluded that this study was exempt from approval because of absence of any risk to participants.

Of the 280 eligible patients who were invited by post to participate in the study, 70 could not be reached after 3 attempts, 17 no longer had a keloid, 38 indicated they did not wish to participate, 8 had another skin disease besides keloids, and 41 did not complete the online survey, leaving 106 patients who successfully completed the questionnaires (36 from a dermatology department, and 70 from a plastic surgery department). The response rate was 57%. Socio-demographic and clinical characteristics of the responders are shown in Table I. Of the non-responders, 49% were male and the mean age was 39.1 years (SD 13.0, range 18–72 years), which was comparable to the responders (Table I).

The outcomes for all the individual dimensions of the SF-36, as well as the PCSs and MCSs of the keloid patients were compared with an age-matched Dutch reference population, including healthy and unhealthy subjects with a living area and sex distribution comparable to our study population (Table II) (16). Compared with the reference population, keloid patients scored considerably lower on the SF-36 dimensions bodily pain, vitality, and social functioning as well as on the MCS, meaning that keloid patients reported a worse mental HRQL. The effect size for the MCS was –0.28, indicating a small effect (20). This is in contrast to the PCS, which was similar to that of the reference population (Table II).

The relationship between HRQL and the individual independent variables sex, age, skin colour, visibility of keloids, quantity of keloids, disease duration, hospital department, and all PSAS items were analysed. Pain and itch were correlated to all Skindex-29 scales (ranging from r_s 0.44 to 0.75, p < 0.001), to both SF-36 component summary scores (ranging from r_s –0.24 to –0.29, p < 0.012) and the EQ-5D-5L index (–0.54, p < 0.001), meaning pain and itch were associated with nearly all HRQL measures. In addition, scar stiffness, thickness, and irregularity showed high correlations with HRQL outcomes. Duration of disease, skin colour, and department type (dermatology vs plastic surgery) showed no significant association with HRQL. Female sex correlated with worse outcomes on emotional, symptomatic, and sum scores of the Skindex-29 (r_p 0.23–0.24, p < 0.017).

Regression analyses revealed that pain was a negative HRQL indicator in 6 (moderate effect on all Skindex-29 scales, small effect on PCS, and moderate effect on EQ-5D-5L index), and itch in 4 (large effect on symptomatic Skindex-29 and moderate effect on Skindex-29 sum, MCS and EQ-5D-5L) models, respectively, making these the most consistent and strongest indicators of HRQL. Besides pain and itch, other indicators were age (moderate effect on PCS), keloid visibility (small effect on MCS), number of keloids (small effect on emotional, functional and sum Skindex-29), scar stiffness (moderate effect on PCS and EQ-5D-5L index) and irregularity (small effect on emotional, functional and sum Skindex-29). Keloid colour was present as indicator in 2 models, but a more aberrant scar colour improved the HRQL, while there was no proof of multi-collinearity. The Skindex-29 models could explain between 29% and 60% of the variability in outcome (R²) and for the PCS, MCS, and EQ-5D-5L index it was 17%, 11%, and 34%, respectively (Table III).

In this study HRQL, specifically emotional wellbeing, of patients with keloid disease was considerably lower compared with a matched reference population on the generic instrument SF-36. This corresponds with the large proportion of keloid patients with severe impairment on the emotional scale of the Skindex-29, while the symptomatic and functional Skindex-29 scales were less affected, with 27% and 25% (12). Reinholz et al. (9) found similar results on HRQL of keloid patients using the Dermatology Life Quality Index (DLQI); specifically symptoms and feelings were affected.

Factors associated with worse HRQL of keloid patients were pain and itch symptoms that are more prominent in keloids than in other scar types (12). Remarkably, cosmetic issues correlated less, or even inconsistently with HRQL. These findings support priority setting, as surgery for cosmetic issues can be interpreted as “luxury healthcare”, instead of a medical need, which relates to its current lower priority in health policy decision-making (21). The current study showed that HRQL can be considerably impaired in patients with keloid disease, causing reasonable doubt on current priority setting.

Skin colour, age, and disease duration did not interact with HRQL. Generally, pain and itch are frequently reported symptoms of keloid disease (1). Of the patients with pain and itch scores >3, 70% had severe emotional HRQL impairment (Skindex-29) compared with 16% in the group of patients that had low pain and itch scores. Moreover, we showed that pain and itch were consistently and strongly associated with HRQL impairment.

A previous study on HRQL in patients with scars found less pain (26%) and itch (44%) complaints and minimal correlations of pain and itch with emotional HRQL (4). These discrepancies can be explained by the large differences between keloids and other scar types, which are less severe than keloids.

Furtado et al. (8) specifically studied keloid patients and similarly found that pain and itch correlated with worse HRQL. They showed non-visible keloids resulted in worse physical HRQL, while we could not find an effect of keloid visibility on physical HRQL. However, we did find impairment of mental HRQL in patients with a visible keloid. Visible keloids could affect HRQL because they are socially more disturbing. Furtado et al. (8) explained that in their population non-visible keloids were long-existing recalcitrant pre-sternal keloids, resulting in worse HRQL in this group.

High-profile reviews on pathological scarring focused mainly on the morphological and disfiguring aspects of keloid disease, and considered the accompanying symptoms of secondary concern (22–24). However, the results of our study challenge this view by clearly showing that itch and pain symptoms are the main indicators of HRQL impairment. Consequently, we believe that these symptoms should be of primary concern in the evaluation and treatment of keloid disease, as well as in scientific research on this topic.

A limitation of the current study is that all patients were recruited from academic hospitals, possibly resulting in a selection bias towards patients with a relatively high burden of disease. This could limit the generalizability of the current results to the entire keloid patient population. On the other hand, the patients from the present study represent those who seek treatment from a medical specialist. The sample was evenly distributed on sex and contained a variety of skin types, disease durations, age groups, and other clinical characteristics and had similar composition to other population-samples described in the literature (9, 12). The incomplete response rate could also have introduced selection bias.

Another issue could be the cross-sectional design with online questionnaires for scar quality and HRQL assessment that completely relied on self-reports. Patients may think that exaggerating their burden may result in better treatment, a higher chance of insurance fees or sick leave. These disease induced benefits, or secondary gains, may have influenced their answers. However, a large part of our study group was not currently under treatment or clinically re-evaluated, and was probably less affected by secondary gains.

Our previous report (12) and the present report show that keloid disease is strongly associated with mental and emotional HRQL impairment, which suggests a high need for effective treatment and thus a priority in healthcare policymaking. HRQL is most severely affected in patients with an itching or painful keloid, suggesting that, in these patients, cosmetic appearance is less of a concern than physical symptoms.

We are indebted to the NutsOhra Foundation. We also thank Dr F. B. Niessen, Professor Dr E. P. Prens and Dr E. Hajderbegovic for their kind help.

The authors declare no conflict of interest.