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Abstract

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

This study explored the epidemiology, treatment, and comorbidities of juvenile psoriasis in Germany using health insurance data. Psoriasis is a chronic inflammatory skin condition that affects approximately 2% to 3% of the world's population. Data were obtained from a database of approximately 6.7 million individuals registered with health insurance organizations throughout Germany. The analysis considered all individuals age 18 years and younger with psoriasis who were registered in 2007. Comorbidities were identified using software based on a morbidity-based risk adjustment model. A total of 138,338 patients with a diagnosis of psoriasis were identified in the database, yielding a prevalence of 2.1%. Within this group there were 4,499 children and adolescents (≤18 years of age), a prevalence of 0.4%. The prevalence ranged from 0.1% at the age of 1 year to 0.8% at the age of 18 years. Most of the patients were treated with topical corticosteroids (72.2%) and antipsoriatics (e.g., tars, psoralen; 20.0%). Immunosuppressants were used in 3.3% of the cases. Juvenile psoriasis was associated with numerous significant comorbidities such as rheumatoid arthritis and inflammation (2.1%); delirium, psychosis, and psychotic and dissociative disorder (1.1%); and heart disease (0.6%). Our study demonstrated that psoriasis is more prevalent in children and adolescents than some older international investigations have documented. Analysis of the health insurance data showed that juvenile psoriasis is associated with a range of comorbidities. The data also may suggest an unrecognized burden of mental health problems in young persons with psoriasis.

Psoriasis is a chronic inflammatory skin disease associated with the immune system [1] that affects approximately 2% to 3% of the population [2, 3]. The condition is often characterized by erythematous papules, patches, and plaques covered with silvery scales [4]. Few studies have described the epidemiology of psoriasis in children [5, 6]. Although the incidence of childhood psoriasis is unknown [7], some studies indicate that the first sign of psoriatic symptoms occurs in infants, children, and adolescents [8, 9]. It is estimated that 30% to 50% of adults with psoriasis developed the condition before the age of 20 years [10]. There are limited epidemiologic data on psoriasis in younger individuals [1, 11]. The objective of this study was to obtain data concerning the epidemiology and comorbidity of juvenile psoriasis in Germany based on comprehensive health insurance data.

Patients and Methods

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

Social health insurance in Germany covers approximately 85% of the German population [12]. Data were obtained from a database containing information from several German statutory health insurance (SHI) organizations. This database included patients from all regions of Germany in 2007. A total of 6.7 million individuals were included in the database, representing 9.5% of all insured people in the social health insurance system. The database included 1.2 million individuals age 18 years and younger. The sex distribution was 44.8% female and 55.2% male (Table 1).

Table 1. Sex Distribution in the German SHI Databases, 2007
 TotalAge ≤18 years
N 6,699,1251,215,684
Sex, male/female, %45.3/54.744.8/55.2

Individuals with psoriasis were identified according to the International Classification of Diseases (ICD) Tenth Revision, German Modification, codes applied to all outpatient and hospital contacts. The diagnosis of psoriasis was assumed if there was at least one documented patient contact using the code L40.x and subcodes. In Germany, the ICD coding quality for outpatient diagnoses is labeled as “confirmed diagnosis,” “suspected diagnosis,” “excluded diagnosis,” “history of diagnosis,” or “other.” This is a further description concerning the reliability of the diagnosis. For outpatient contacts, only data labeled “confirmed” were included in the analysis; for inpatient treatment, the primary and secondary diagnoses were both used [13].

Prevalence was adjusted for age and sex using the social health insurance in Germany as standard (everybody enrolled in all SHIs in Germany; unit of time: year). For the identified insured people, the prevalences were age and sex adjusted on the basis of their insured days in comparison to the standard population (insured days in the SHI; [14]). The approximation of the total number of children and adolescents with psoriasis in the SHI was based on the official record type of the German annual compensation statistic for 2007 (German “Satzart [SA] 40,” official statistic of the Federal Insurance Office). For prevalence, the equation for the approximation of a binomial confidence interval (CI; formula 1) was used [15]:

  • display math(1)

where α = alpha error, k = successes in the sample, n = sample size, p = proportion of successes estimated from the statistical sample, r = relative frequency = k/n, and z = number of standard deviations from the mean (z-score). The Anatomical Therapeutic Chemical (ATC) Classification System (2007) was used to classify drugs.

Comorbidities were identified based on the hierarchical disease groups (German: Hierarchische Morbiditätsgruppen [HMG]) and grouped based on the morbidity risk adjustment model that the Federal Insurance Office uses to calculate allocations to SHIs from the Health Fund. For technical reasons, data on comorbidities from a subset of 3.2 million patients were analyzed. For this subset, logistic regression was used to analyze the binary outcome variables. The independent variable (psoriasis) predicted the dichotomous outcome (comorbidity), controlling for age and sex as confounders. Comorbidities (HMG) that were statistically not significant or were reported in fewer than five children and adolescents were not included in the analysis. p < 0.05 was considered statistically significant. Statistical analyses were performed using SPSS Statistics, version 18 for Windows (IBM, Ehningen, Germany).

Results

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

Prevalence

A total of 138,338 patients (including adults) with the diagnosis of psoriasis were identified in the database, yielding a prevalence of 2.10% (95% CI 2.10, 2.10). Psoriasis was identified in 4,499 children and adolescents (age ≤18 years), a prevalence of 0.40% (95% CI 0.40, 0.40). Girls had a higher prevalence (0.44%, 95% CI 0.43, 0.46) than boys (0.35%, 95% CI 0.33, 0.36; Table 2).

Table 2. Juveniles (≤18 years) Identified with a Diagnosis of Psoriasis in the Database
 FemaleMaleTotal
N 2,4541,9954,449
%0.440.350.40
95% confidence interval0.43, 0.460.33, 0.360.40, 0.40

There is an almost linear increase in prevalence with age, from 0.09% (95% CI 0.09, 0.09) at 1 year old to 0.82% (95% CI 0.82, 0.83) at 18 years old. There is remarkable growth of prevalence during the first 18 years (Fig. 1).

image

Figure 1. Juvenile psoriasis: prevalence according to age group (N = 4,449).

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Treatment Data

Patients had on average 1.9 ± 1.4 outpatient contacts coded as psoriasis in the study year. Most of the outpatient contacts occurred during the winter (first and fourth quarter 2007), with the fewest occurring during the summer (third quarter 2007). Most of the diagnoses (46.3%) were for psoriasis vulgaris (L40.0), followed by psoriasis, unspecified (L40.9; 38.4%). With respect to inpatient stays, 1.8% of patients were hospitalized with psoriasis as a primary diagnosis. Children and adolescents who were hospitalized had in average of 1.1 ± 0.5 inpatient stays. The most frequently coded diagnoses for these inpatient stays were psoriasis vulgaris (L40.0; 39.8%) and psoriatic arthropathy (L40.5; 29.3%).

A total of 2,141 children and adolescents (48.1%) were administered a drug for their psoriasis. On average the children and adolescents received 2.4 ± 3.9 drug prescriptions for psoriasis in the study year. Drugs from 55 different ATC categories were used to treat patients. Corticosteroids for dermatologic preparations (D07) were the most common drug identified (72.7%), followed by antipsoriatics (D05; 20.0%), emollients and protectives (D02; 4.0%), and immunosuppressants (L04; 3.3%; Figs. 2 and 3).

image

Figure 2. Juvenile psoriasis: medicines used according to the ATC classification (N = 2,141).

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Figure 3. Juvenile psoriasis: antipsoriatics, emollients and protectives, and immunosuppressants according to the ATC classification (N = 2,141).

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The average cost for a prescribed drug for psoriasis was €85.57 ± 432.33. The cost per package ranged from €5.11 (hydrocortisone) to €5,271.94 (biologic agent). The average cost for the psoriasis drug treatment per patient per year was €122.87 ± 974.20. The cost ranged from €5.11 (one prescription of hydrocortisone) to €28,182.27 (five prescriptions of biologic agents).

Comorbidities

Juvenile psoriasis was associated with a higher rate of comorbidity than in individuals without psoriasis. The prevalence of the comorbidities was (Fig. 4) rheumatoid arthritis and inflammation, 2.1% (non-psoriatic patients 0.1%); delirium, psychosis, psychotic and dissociative disorder, 1.1% (0.4%); depressive episodes, 0.7% (0.2%); heart valve disease and rheumatic heart disease, 0.6% (0.3%); congenital heart disease, 0.6% (0.4%); serious endocrine disease and metabolic disease (including lysosomal storage diseases: ICD E72–E77), 0.4% (0.2%); and hypertonia, 0.3% (0.1%).

image

Figure 4. Comorbidities in juveniles with (Pso; n = 4,499) and without psoriasis (1-Pso; n = 138,338). p < 0.05 was considered statistically significant.

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Children and young adults with psoriasis had on average 0.22 ± 0.54 comorbidities, compared with 0.14 ± 0.44 comorbidities in children and young adults without psoriasis. After adjusting for age and sex, patients with psoriasis had a significantly higher number of comorbidities than patients without psoriasis (p < .001).

Discussion

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

It is not unusual for psoriasis to start in childhood and adolescence, although a mild presentation sometimes makes it difficult to establish a reliable diagnosis at this age [16]. Estimates of the total prevalence of psoriasis in childhood vary from 0.1% to 3.0% [17, 18]. Using data from several German SHI organizations, the present study showed that psoriasis is more common in children than has been documented previously.

To aid comparisons with other methodologically similar studies [18], prevalence was calculated separately for ages 0 to 9 years (0.18%) and 10 to 19 years (0.83%). The prevalence of psoriasis in the present study population also underlines results of an earlier study from Germany that found a prevalence of 0.37% in children age 0 to 9 years and 1.01% in children age 10 to 19 years [11]. The study results are also somewhat consistent with those of another from the Netherlands (age 0–10 years, 0.4%; age 11–19, 1.0%) [10] and a study from the United Kingdom (age 0–9 years, 0.55%; age 10–18 years, 1.37%) [1]. Preliminary results from a 2009 study using routine German SHI with almost 300,000 children and adolescents also show a similar prevalence of psoriasis in those age 18 years and younger (0.45%) [18]. Although the prevalence of other common dermatologic conditions, such as acne and atopic eczema, is higher than that of juvenile psoriasis [11], our study highlights that juvenile psoriasis is common in children and adolescents.

This study found that the treatment of psoriasis in childhood is conservative, with most children and adolescents treated using topical corticosteroids or antipsoriatics. This could be a result of uncertainty over appropriate therapy in juvenile patients resulting in prescribers opting to use a conservative therapy with a lower risk of long-term side effects. These results indicate that the treatment of psoriasis still represents a particular challenge. “Children are not small adults” [16] and need a different therapy.

Several comorbidities associated with psoriasis were identified. The present data highlight that a specific group of comorbidities known to be associated with adult psoriasis (e.g., hypertonia) are also associated with childhood psoriasis [11]. Rheumatoid arthritis and inflammation was the most common comorbidity of childhood psoriasis and was more prevalent in children and adolescents with psoriasis than in those without of the same age and sex. The analyses showed that childhood psoriasis was also associated with mental health problems (e.g., depressive episodes). These results correspond to those of earlier studies in which children and adolescents with psoriasis had a higher risk of developing psychiatric disorders, especially depression and anxiety, than did those without [16, 19, 20]. Previous studies have shown that psoriasis can have a significant negative effect on the emotional and psychosocial well-being of affected children and adolescents [2, 21, 22].

There are some limitations that need to be considered in the present study. Although the study included a large number of individuals, the data are not a sample from the whole population but came from several health insurance companies with unique characteristics (e.g., region, morbidity-based risk structure). Patients could be identified only if they had at least one contact with their doctor during 2007. In addition, the routine data used provided no information about clinical details, such as the severity of the psoriasis.

Conclusion

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

Using a national database of 6.7 million nonselected patients covered by national health insurance in Germany, this study showed that psoriasis is a disorder in juveniles (age ≤18 years), with an overall prevalence of 0.40%. Furthermore, the study showed that psoriasis in childhood is associated with statistically significantly greater comorbidity than in juveniles without psoriasis. Most of the juvenile patients were treated with topical corticosteroids and antipsoriatics. The treatment was conservative in younger patients. Further research is needed to generate more epidemiologic data for more in-depth comparisons and to help inform the management of psoriasis in children.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References

We would like to thank Erin Penno and Simon Horsburgh from the Department of Preventive and Social Medicine at the University of Otago in New Zealand for the English review of this article. The study was supported by an unrestricted grant from Pfizer, Germany. Pfizer, Germany played no role in the design or execution of the study or in data collection, data management, data analysis, interpretation of the data, publication preparation, publication review, or publication approval.

References

  1. Top of page
  2. Abstract
  3. Patients and Methods
  4. Results
  5. Discussion
  6. Conclusion
  7. Acknowledgments
  8. References