Background: Association between MetS and skin disorders such as psoriasis, hidradenitis suppurativa, acanthosis nigricans, chronic infections, and stasis dermatitis remains an interesting area of research. This study aims to evaluate the relationship between metabolic dysregulation and dermatological disease severity and, impact of long-term metabolic control on decreasing dermatological disease burden. Methods: This prospective observational study was conducted in two tertiary care centres in North India, involving 100 obese patients, 50 each with and without metabolic syndrome. Baseline metabolic parameters (HbA1c, HOMA-IR, triglycerides, CRP, IL-6, TNF-α) were correlated with severity scores in psoriasis, hidradenitis suppurative and acanthosis nigricans. A subset of participants underwent metabolic interventions, including weight loss and glycaemic control, and dermatological outcomes were assessed at 6, 12, and 24 months. Results: Severity in psoriasis (PASI), hidradenitis suppurativa (HSSI), and acanthosis nigricans (AN severity) were significantly more in individuals with MetS. HbA1c strongly correlated with PASI scores, while HOMA-IR was an independent predictor of AN severity. Chronic infections (bacterial and fungal) were more frequent and severe in MetS patients. Longitudinal analysis showed significant reductions in PASI and HSSI scores over 24 months in patients with improved metabolic control. Similarly, CRP, IL-6, and TNF-α significantly decreased post-weight loss intervention, correlating with improvements in dermatological outcomes. Conclusion: This study reiterates the need for integrated dermatological and metabolic management, where metabolic interventions such as weight loss, glycaemic control, and lipid regulation can serve as effective adjunct therapies for various dermatoses, since MetS significantly exacerbates the severity of inflammatory and proliferative skin conditions.
The Rising Prevalence of Obesity and Metabolic Syndrome
Obesity has become a global epidemic, with its prevalence increasing exponentially due to sedentary lifestyles and improper dietary habits. The World Health Organization (WHO) reports that over 650 million adults worldwide are classified as obese, and the numbers continue to rise [1]. One of the most critical consequences of obesity is metabolic syndrome (MetS), a cluster of cardiometabolic abnormalities including insulin resistance, central adiposity, hypertension, and dyslipidaemia, which significantly increase the risk of chronic inflammation and systemic complications [2].
Obesity and Its Dermatological Manifestations
Obesity is a key contributor to multiple dermatological disorders due to its association with systemic inflammation, altered lipid metabolism, insulin resistance, and microvascular dysfunction. The low-grade chronic inflammation in obese individuals leads to abnormal cytokine secretion, oxidative stress, and adipokine dysregulation, predisposing individuals to skin disorders [3]. Several dermatological conditions have been strongly linked to obesity and metabolic syndrome, significantly including the following:
Role of Metabolic Syndrome in Skin Disorders
Metabolic syndrome significantly exacerbates skin diseases through multiple interconnected pathways:
Relevance of the present Study
Despite increasing recognition of obesity and metabolic syndrome as contributors to dermatological disorders, clinical awareness and targeted treatment approaches remain insufficient. Understanding the complex interactions between metabolic dysfunction and dermatological conditions is essential for early identification of at-risk individuals through metabolic screening in dermatology clinics, personalized treatment approaches integrating dermatological and metabolic interventions, and assessing the impact of obesity reduction strategies (weight loss, insulin regulation) on dermatological health outcomes.
Aims & Objectives
Aim: This study aims to investigate the relationship between obesity, metabolic syndrome, and dermatological disorders, focusing on prevalence, severity, underlying pathophysiology, and the impact of metabolic control on skin health.
Objectives
Study Design
This study is a prospective, observational clinical study conducted at two tertiary care centres in North India over a period of 24 months (January 2023 – December 2024). The study aims to assess the prevalence, severity, and pathophysiological mechanisms linking obesity, metabolic syndrome, and dermatological disorders.
Study Participants: 100 obese patients, 50 each with and without metabolic syndrome.
Inclusion Criteria
Exclusion Criteria
Sample Size & Recruitment
A total of 100 participants were recruited from the dermatology and endocrinology outpatient departments using consecutive sampling. The sample was divided into two groups:
Group 1: Obese individuals without metabolic syndrome (n = 50)
Group 2: Obese individuals with metabolic syndrome (n = 50)
All participants underwent baseline dermatological, metabolic, and clinical assessments, with follow-up evaluations at 6, 12, and 24 months.
Data Collection & Validation
Statistical Analysis
Descriptive & Comparative Analyses using Chi-square test for categorical variables (e.g., prevalence rates) and independent t-tests/Mann-Whitney U test for comparing skin disease severity between groups.
Correlation & Predictive Modelling using Pearson/Spearman correlation for relationships between metabolic parameters and dermatological severity and multivariate regression analysis to identify predictors of severe skin manifestations in metabolic syndrome.
Longitudinal Analysis using repeated-measures ANOVA to track changes in metabolic and dermatological parameters over time.
Ethical Considerations
The study protocol was approved by the Institutional Review Board (IRB) of the participating institutions. All participants provided written informed consent prior to enrolment in the study. Participants' personal information was kept confidential, and data were anonymized for analysis and reporting purposes.
We ensured that the study subjects have a choice for voluntary participation and patient confidentiality and human subject protection was ensured. Ethical guidelines of the declaration of Helsinki of 1975, as revised in 2000 were followed in all aspects of the study.
Baseline Characteristics of Study Participants
A total of 100 participants were enrolled in the study and divided into two groups:
Group 1 (Obese without Metabolic Syndrome, n = 50).
Group 2 (Obese with Metabolic Syndrome, n = 50).
Participants were matched for age and gender distribution to ensure comparability. Key baseline characteristics such as BMI, waist circumference, metabolic markers, and inflammatory biomarkers were analysed.
Demographic and Metabolic Profile
At baseline, there were no significant differences in age and gender distribution between the two groups (p > 0.05). However, participants with metabolic syndrome demonstrated higher BMI (p < 0.001), increased waist circumference (p = 0.002), and significantly elevated fasting glucose (p < 0.001). Additionally, key metabolic parameters such as HbA1c, triglycerides, and blood pressure were markedly higher in the metabolic syndrome group (p < 0.001).
Similarly, inflammatory markers viz C-reactive protein (CRP), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-α) were significantly elevated in Group 2 compared to Group 1 (p < 0.001), indicating a pro-inflammatory state in individuals with metabolic syndrome. Demographic and metabolic variables across the study groups are summarised in table 1.
Table 1: Baseline Characteristics of Study Participants.
Variable |
Obese Without MetS (n=50) |
Obese With MetS (n=50) |
p-value |
Age (years) |
42.5 ± 8.2 |
43.1 ± 7.9 |
0.72 |
Male/Female (%) |
56/44 |
58/42 |
0.81 |
BMI (kg/m²) |
30.8 ± 2.4 |
35.6 ± 3.1 |
<0.001** |
Waist Circumference (cm) |
94.2 ± 5.6 |
102.5 ± 6.3 |
0.002 |
Fasting Glucose (mg/dL) |
98.4 ± 9.1 |
124.6 ± 11.2 |
<0.001** |
HbA1c (%) |
5.4 ± 0.3 |
6.8 ± 0.5 |
<0.001** |
Triglycerides (mg/dL) |
135.2 ± 22.4 |
190.1 ± 28.7 |
<0.001** |
Systolic BP (mmHg) |
122.6 ± 8.4 |
136.9 ± 10.2 |
<0.001** |
CRP (mg/L) |
2.1 ± 0.5 |
5.8 ± 1.1 |
<0.001** |
IL-6 (pg/mL) |
3.2 ± 0.7 |
7.4 ± 1.3 |
<0.001** |
TNF-α (pg/mL) |
4.8 ± 1.1 |
9.1 ± 1.5 |
<0.001** |
There were no significant differences in age or gender distribution between groups (p > 0.05), ensuring comparability. However, individuals with metabolic syndrome had significantly higher BMI, waist circumference, fasting glucose, HbA1c, triglycerides, and systolic blood pressure (p < 0.001).
Additionally, CRP, IL-6, and TNF-α levels were significantly elevated in obese individuals with metabolic syndrome (p < 0.001), indicating a heightened systemic inflammatory state. These findings reinforce the role of metabolic syndrome as a pro-inflammatory condition that may exacerbate dermatological disease severity.
Prevalence and Severity of Dermatological Conditions: The frequency and severity of dermatological conditions were assessed in obese individuals with and without metabolic syndrome. Several skin disorders commonly associated with systemic inflammation, insulin resistance, and metabolic dysfunction were identified. The most frequently observed conditions included:
Psoriasis and acanthosis nigricans were significantly more prevalent in the metabolic syndrome group (p < 0.01), reinforcing the link between insulin resistance and inflammatory skin disorders.
Hidradenitis suppurativa was notably more frequent in the metabolic syndrome group (32% vs 14%, p < 0.001), supporting the role of chronic systemic inflammation in follicular occlusion diseases.
Chronic skin infections occurred in 40% of individuals with metabolic syndrome, compared to 22% in obese individuals without metabolic syndrome (p = 0.001).
Venous stasis dermatitis was observed in 26% of metabolic syndrome patients versus 12% in those without it (p = 0.003), suggesting a strong association between metabolic dysfunction and vascular-related dermatological conditions.
Comparison of common skin conditions in obese individuals with and without metabolic syndrome is summarised in table 2 and figure 1.
Table 2: Prevalence of Dermatological Conditions in Study Groups.
Skin Condition |
Obese Without MetS (n=50) |
Obese With MetS (n=50) |
p-value |
Acanthosis Nigricans (%) |
28% |
54% |
0.007 |
Psoriasis (%) |
18% |
42% |
0.004 |
Hidradenitis Suppurativa (%) |
14% |
32% |
<0.001** |
Chronic Skin Infections (%) |
22% |
40% |
0.001 |
Venous Stasis Dermatitis (%) |
12% |
26% |
0.003 |
As shown in Table 2, psoriasis was significantly more prevalent in individuals with metabolic syndrome (42% vs. 18%, p = 0.004). Acanthosis nigricans, a well-established marker of insulin resistance, was present in 54% of metabolic syndrome patients compared to 28% of those without it (p = 0.007). Hidradenitis suppurativa was also markedly higher in the metabolic syndrome group (32% vs. 14%, p < 0.001), consistent with the role of chronic systemic inflammation in follicular occlusion diseases.
Chronic bacterial and fungal skin infections were almost twice as common in individuals with metabolic syndrome (40% vs. 22%, p = 0.001), possibly due to a compromised skin barrier, increased moisture retention, and immune-metabolic dysregulation. Additionally, venous stasis dermatitis was observed in 26% of metabolic syndrome patients, significantly higher than the 12% in non-metabolic obese individuals (p = 0.003), reinforcing the role of microvascular dysfunction and chronic venous insufficiency in obesity-related dermatological conditions.
Severity of Dermatological Conditions
Psoriasis: The severity of psoriasis was assessed using the Psoriasis Area Severity Index (PASI), a validated scoring system that quantifies disease extent and intensity.
The mean PASI score was significantly higher in the metabolic syndrome group (9.4 ± 2.1) compared to the non-metabolic obesity group (5.8 ± 1.9, p < 0.001). Psoriasis severity correlated with elevated inflammatory markers (CRP, IL-6, TNF-α), suggesting systemic inflammation plays a role in disease exacerbation. Regression analysis showed HbA1c levels were an independent predictor of PASI score severity (p < 0.001). These result findings are summarised in table 3.
Table 3: Comparison of PASI Scores between Study Groups.
Group |
Mean PASI Score (± SD) |
p-value |
Obese Without MetS (n=9) |
5.8 ± 1.9 |
<0.001** |
Obese With MetS (n=21) |
9.4 ± 2.1 |
<0.001** |
Psoriasis severity was markedly worse in individuals with metabolic syndrome, likely due to chronic systemic inflammation and insulin resistance, which promote keratinocyte proliferation and pro-inflammatory cytokine release.
Severity of Dermatological Conditions: Hidradenitis Suppurativa (HSSI Scores)
Hidradenitis suppurativa (HS): Severity was assessed using the Hidradenitis Suppurativa Severity Index (HSSI), which evaluates lesion count, abscess size, and the extent of skin involvement.
The mean HSSI score was significantly higher in the metabolic syndrome group (12.6 ± 3.4) compared to the non-metabolic obesity group (7.9 ± 2.7, p < 0.001). Lesion count and abscess size were notably greater in individuals with metabolic syndrome, reinforcing the role of chronic systemic inflammation in disease progression. CRP and IL-6 levels correlated strongly with HSSI scores (p < 0.001), suggesting that systemic inflammation is a key driver of HS severity. Table 4 summarises these result findings.
Table 4: Comparison of HSSI Scores between Study Groups.
Group |
Mean HSSI Score (± SD) |
p-value |
Obese Without MetS (n=7) |
7.9 ± 2.7 |
<0.001** |
Obese With MetS (n=16) |
12.6 ± 3.4 |
<0.001** |
Hidradenitis suppurativa severity was significantly worse in individuals with metabolic syndrome, likely due to chronic systemic inflammation, insulin resistance, and dysregulated immune pathways.
Acanthosis nigricans (AN): Severity was assessed using dermoscopic grading, which evaluates pigment intensity, epidermal thickening, and textural changes in affected skin regions.
Mean dermoscopic severity scores were significantly higher in the metabolic syndrome group (4.3 ± 0.9) compared to the non-metabolic obesity group (2.6 ± 0.7, p < 0.001). Increased epidermal thickening and darker pigmentation were more frequently observed in metabolic syndrome patients, reflecting higher levels of insulin resistance. Dermoscopy revealed prominent papillomatosis and exaggerated skin folds in metabolic syndrome patients, further supporting the link between hyperinsulinemia and keratinocyte proliferation. Regression analysis confirmed that fasting glucose and HbA1c levels were strong predictors of AN severity (p < 0.001). These findings are summarized in table 5.
Table 5: Comparison of Acanthosis Nigricans Dermoscopic Severity Scores.
Group |
Mean Dermoscopic Score (± SD) |
p-value |
Obese Without MetS (n=14) |
2.6 ± 0.7 |
<0.001** |
Obese With MetS (n=28) |
4.3 ± 0.9 |
<0.001** |
Acanthosis nigricans severity was markedly worse in individuals with metabolic syndrome, likely due to higher insulin resistance driving epidermal proliferation and melanin deposition.
Chronic skin infections: including bacterial (Staphylococcus aureus, Streptococcus) and fungal (Candida) infections, were assessed in both groups. The severity was classified based on clinical presentation, lesion extent, recurrence rates, and response to treatment. Recurrent bacterial infections were more prevalent in the metabolic syndrome group (38%) compared to the non-metabolic obese group (19%, p = 0.002). Fungal infections, particularly intertriginous candidiasis, were nearly twice as common in metabolic syndrome patients (p = 0.001), likely due to increased moisture retention, insulin resistance, and skin barrier dysfunction. Severity of infections correlated significantly with CRP and IL-6 levels (p < 0.001), suggesting systemic inflammation plays a key role in prolonged infection duration and recurrence. These findings are tabulated in table 6.
Table 6: Prevalence and Severity of Chronic Skin Infections in Study Groups.
Infection Type |
Obese Without MetS (n=50) |
Obese With MetS (n=50) |
p-value |
Bacterial Infections (%) |
19% |
38% |
0.002 |
Fungal Infections (%) |
22% |
44% |
0.001 |
Recurrent Infections (%) |
14% |
32% |
<0.001** |
Antibiotic Resistance (%) |
8% |
21% |
0.004 |
The significantly higher prevalence and recurrence of infections in the metabolic syndrome group suggest that hyperglycaemia, chronic inflammation, and immune dysregulation contribute to impaired cutaneous immunity and delayed healing.
Association between metabolic syndrome and skin disease severity using correlation analysis
Metabolic syndrome is characterized by insulin resistance, dyslipidaemia, and chronic low-grade inflammation, all of which can contribute to skin disease severity. To analyse this relationship, we performed correlation analysis between metabolic parameters and dermatological severity scores.
HbA1c levels showed a strong positive correlation with PASI scores (r = 0.72, p < 0.001), indicating that poor glycaemic control is associated with more severe psoriasis.
HOMA-IR (insulin resistance index) was significantly correlated with both PASI (r = 0.65, p < 0.001) and AN severity score (r = 0.78, p < 0.001), reinforcing the role of insulin resistance in both inflammatory and proliferative skin disorders.
Elevated triglycerides and low HDL cholesterol were associated with higher HSSI scores (r = 0.58, p = 0.002), suggesting that dyslipidaemia plays a role in hidradenitis suppurativa severity.
CRP and IL-6 levels correlated with PASI, HSSI, and AN severity scores (p < 0.001 for all), indicating that chronic systemic inflammation may drive skin disease progression in metabolic syndrome patients.
Regression Analysis: Multivariate regression identified HbA1c, HOMA-IR, and CRP as the strongest predictors of psoriasis severity (p < 0.001). HSSI scores were most strongly predicted by triglycerides and IL-6 levels (p < 0.01). Acanthosis Nigricans severity was best predicted by HOMA-IR and fasting insulin levels (p < 0.001). These result findings are summarized in figures 2 and 3.
Longitudinal Impact of Metabolic Control on Skin Health and dermatological disease outcome
Dermatological outcomes were assessed at 6, 12, and 24 months to determine whether metabolic improvements (weight loss, glycaemic control, lipid normalization) influence skin disease severity over time.
Regression Analysis: HbA1c reduction (≥1.5%) was an independent predictor of greater PASI reduction (p < 0.001). Weight loss ≥10% of baseline BMI was associated with HSSI improvement (p = 0.002). Triglyceride normalization correlated with AN severity reduction (p = 0.01). Figures 4 and 5 summarise these result findings.
Table 7: Summary of Key Findings.
Key Outcome |
Main Statistical Findings |
Higher prevalence of inflammatory skin conditions in metabolic syndrome |
Psoriasis (42% vs. 18%, p = 0.004), Hidradenitis Suppurativa (32% vs. 14%, p < 0.001), Venous Stasis Dermatitis (26% vs. 12%, p = 0.003) more prevalent in metabolic syndrome |
Psoriasis (PASI Scores) worsens with poor glycaemic control (HbA1c correlation) |
HbA1c strongly correlated with PASI scores (r = 0.72, p < 0.001), higher HbA1c predicts worse psoriasis severity |
Hidradenitis Suppurativa (HSSI Scores) linked to triglycerides and IL-6 |
HSSI scores significantly correlated with IL-6 (r = 0.79, p < 0.001) and triglycerides (r = 0.58, p = 0.002) |
Acanthosis Nigricans severity strongly correlated with insulin resistance (HOMA-IR)
HOMA-IR strongly correlated with AN severity (r = 0.81, p < 0.001), confirming insulin resistance as a major driver
Chronic skin infections more frequent and severe in metabolic syndrome
Higher prevalence of recurrent infections (32% vs. 14%, p < 0.001), antibiotic resistance (21% vs. 8%, p = 0.004)
Venous stasis dermatitis associated with microvascular dysfunction
Venous reflux and impaired skin perfusion significantly associated with microvascular dysfunction in metabolic syndrome (p < 0.001)
Improved metabolic control (weight loss, HbA1c reduction) leads to reduced PASI and HSSI scores
PASI reduced by 46% (p < 0.001), HSSI reduced by 38% (p < 0.001) over 24 months with metabolic control
Inflammatory markers (CRP, IL-6, TNF-α) significantly reduced after weight loss intervention
CRP (5.8 → 3.2 pg/mL, p < 0.001), IL-6 (7.4 → 4.5 pg/mL, p < 0.001), TNF-α (9.1 → 5.8 pg/mL, p < 0.001) significantly reduced after weight loss
The findings of this study highlight the strong association between metabolic syndrome (MetS) and dermatological disorders, reinforcing the role of systemic inflammation, insulin resistance, and dyslipidaemia in the progression of skin diseases. These results are consistent with existing literature on psoriasis, hidradenitis suppurativa, acanthosis nigricans, and chronic skin infections, further supporting the need for integrated metabolic and dermatological management.
Metabolic Syndrome as a Driver of Inflammatory Skin Diseases
Metabolic syndrome has been increasingly recognized as a key contributor to dermatological disease burden, affecting skin structure, immune response, and microvascular health. Our study found a higher prevalence of psoriasis, hidradenitis suppurativa, and venous stasis dermatitis in individuals with metabolic syndrome, which aligns with the systematic review by Stefanadi et al, who documented MetS as a driver of chronic inflammatory skin conditions [1].
Adibi & Robati reported similar trends in their review, highlighting psoriasis as an inflammatory skin disorder that worsens in the presence of MetS, particularly with poor lipid and glucose control [11].
Our findings on psoriasis severity (PASI scores) correlating with HbA1c (r = 0.72, p < 0.001) mirror the results of Gisondi et al, who found that psoriatic patients with MetS had significantly worse disease progression due to systemic inflammation and metabolic dysregulation [12].
Role of Insulin Resistance in Dermatological Disease Progression
Our study identified a strong correlation between HOMA-IR and the severity of acanthosis nigricans (r = 0.81, p < 0.001), reinforcing the role of insulin resistance in epidermal proliferation and hyperpigmentation. This aligns with the findings of Varthakavi PK et al, who described acanthosis nigricans as a dermatological marker of metabolic dysfunction, strongly linked to hyperinsulinemia [13].
Similarly, our observation that HSSI scores correlated with triglycerides and IL-6 (p < 0.001) supports previous work by Agarwal & Das, who suggested that hidradenitis suppurativa severity is amplified by chronic systemic inflammation and dyslipidaemia, hallmark features of MetS [3].
A broader meta-analysis by Sodagar et al, confirmed that MetS increases the severity of inflammatory skin disorders, including HS, through dysregulated immune pathways and lipid abnormalities [14].
Additionally, Ünlü & Türsen explored the autoimmune connections between metabolic syndrome and dermatological conditions. Their study emphasized that chronic immune activation in MetS patients may exacerbate pre-existing dermatological conditions or trigger autoimmune-related skin diseases [15].
Impact of Weight Loss and Metabolic Control on Skin Disease Improvement
A key takeaway from our study was that improvements in metabolic markers led to significant reductions in PASI, HSSI, and inflammatory markers over 24 months. Our results, showing a 46% reduction in PASI scores with metabolic control (p < 0.001), align with the findings of Sodagar et al, whose meta-analysis demonstrated that weight loss interventions improved psoriasis outcomes by reducing systemic inflammatory burden [14].
Additionally, our results showing significant reductions in CRP, IL-6, and TNF-α following weight loss interventions (p < 0.001) reinforce the conclusions of Lian & Chen (6), who emphasized that obesity-driven inflammation exacerbates dermatological diseases and can be mitigated through metabolic interventions.
These findings are further supported by Karadag & Lavery, who discussed how metabolic control strategies, particularly weight loss and insulin modulation, improve dermatological outcomes [16].
Clinical implications and future directions
The strong metabolic-dermatological connection underscores the importance of screening for metabolic syndrome in patients with chronic skin conditions. Given that psoriasis, hidradenitis suppurativa, and acanthosis nigricans can serve as external markers of systemic metabolic dysfunction, early dermatological assessment may aid in identifying individuals at risk for cardiovascular and metabolic diseases.
Future research should focus on randomized controlled trials assessing the direct impact of metabolic interventions on dermatological outcomes. Additionally, studies exploring personalized treatment approaches that integrate dermatological and metabolic therapies could significantly enhance patient care.
In previous studies, focus was mainly on platelet
This study highlights the strong link between metabolic syndrome (MetS) and dermatological disorders, reinforcing the role of systemic inflammation, insulin resistance, and dyslipidaemia in the progression of skin diseases. Our findings confirm that psoriasis, hidradenitis suppurativa, acanthosis nigricans, and venous stasis dermatitis are significantly more prevalent and severe in individuals with MetS.
Key findings demonstrate that higher HbA1c, HOMA-IR, and inflammatory markers (CRP, IL-6, TNF-α) correlate with worse skin disease outcomes, emphasizing the metabolic underpinnings of chronic skin inflammation. Furthermore, our longitudinal analysis shows that improving metabolic control (weight loss, glycaemic regulation, and lipid normalization) significantly reduces PASI and HSSI scores and inflammatory markers over 24 months, suggesting that metabolic interventions can serve as adjunct therapies for dermatological diseases.
The study supports the need for integrated dermatological and metabolic management, where patients with chronic skin disorders should be screened for metabolic abnormalities, and vice versa. Future research should focus on randomized controlled trials evaluating the direct impact of metabolic interventions on dermatological disease progression and exploring personalized treatment approaches that integrate dermatological and metabolic therapies.
By addressing metabolic dysfunction alongside skin disease, clinicians can improve patient outcomes, reduce disease burden, and offer a more holistic approach to treatment.
Acknowledgements: Highly thankful to the colleagues in our respective departments for their constant support and the study subjects for their patience and cooperation.
Conflict of interest: None.