Dupuytren's disease in France--1831 to 2001--from description to economic burden

Dupuytren Disease: Prevalence, Incidence, and Lifetime Risk of Surgical Intervention. A Population-Based Cohort Analysis

BACKGROUND

Health care burden attributable to Dupuytren disease (DD) is largely unknown. The authors determined (1) the prevalence and incidence of DD, (2) the incidence of first surgical intervention, and (3) the lifetime risk of surgical intervention in the United Kingdom National Healthcare Service.

METHODS

In this population-based dynamic cohort analysis, data of the Clinical Practice Research Datalink was linked to Hospital Episode Statistics, to characterize the diagnosis and surgical treatment of DD. Secular trends of incidence of DD diagnosis and first surgical treatment were calculated for 2000 to 2013. A multistate Markov model was designed to estimate the lifetime risk of first surgical intervention.

RESULTS

A total of 10,553,454 subjects were included in the analyses, 5,502,879 (52%) of whom were women. Of these, 38,707 DD patients were identified. Point prevalence in 2013 was 0.67% (99% CI, 0.66 to 0.68). The incidence of DD almost doubled from 0.30 (99% CI, 0.28 to 0.33) per 1000 person-years in 2000, to 0.59 (99% CI, 0.56 to 0.62) per 1000 person-years in 2013. The incidence of first surgical intervention similarly increased from 0.29 (99% CI, 0.23 to 0.37) to 0.88 (99% CI, 0.77 to 1.00) in the same period. A man or woman newly diagnosed with DD at age 65 has a lifetime risk of surgical intervention of 23% and 13%, respectively, showing only a very subtle decrease when diagnosed later in life.

CONCLUSIONS

DD is an important health condition in the older population, because prevalence and incidence rates have almost doubled in the past decade. Estimated lifetime risk of surgical treatment is relatively low, but almost twice in men compared with women.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Outcomes and Direct Costs of Needle Aponeurotomy, Collagenase Injection, and Fasciectomy in the Treatment of Dupuytren Contracture

PURPOSE

The aims of our study were to evaluate the rates and predictors of reinterventions and direct costs of 3 common treatments of Dupuytren contractures-needle aponeurotomy, collagenase injection, and surgical fasciectomy.

METHODS

A retrospective review identified 848 interventions for Dupuytren contracture in 350 patients treated by a single surgeon from 2005 to 2016. The treatments included needle aponeurotomy (NA) (n = 444), collagenase injection (n = 272), and open fasciectomy (n = 132). We collected information on demographics, contracture details, and comorbidities. Outcomes included reintervention rates, time to reintervention, and direct cost of treatments. Standardized costs were calculated by applying 2017 Medicare reimbursement to professional services and cost-to-charge ratios to hospital charges.

RESULTS

Demographics were similar among the 3 treatment groups. The fifth finger was the most commonly affected digit including 43% of the NA, 60% of the collagenase, and 45% of the fasciectomy groups. The 2-year rates of reintervention following NA, collagenase, and fasciectomy were 24%, 41%, and 4%, respectively, and the 5-year rates were 61%, 55%, and 4%, respectively. Younger age and severity of preintervention proximal interphalangeal (PIP) joint contracture were predictive of reintervention in the NA and collagenase groups. The standardized direct costs for NA, collagenase, and fasciectomy were $624, $4,189, and $5,291, respectively. Including all reinterventions, the cumulative costs per digit following NA, collagenase, and surgery at 5 years were $1,540, $5,952, and $5,507, respectively.

CONCLUSIONS

Treatment with collagenase resulted in the highest rate of reintervention at 2 years, comparable reintervention rates to NA at 5 years, and the highest cumulative costs. The NA was the least expensive and resulted in longer duration before reintervention compared with collagenase. More severe PIP joint contractures and younger age at time of initial intervention were predictive of reintervention after collagenase and NA. Fasciectomy has a high initial cost but the lowest reintervention rate.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Impact on costs of switching one-ray aponeurectomy to percutaneous needle aponeurotomy in Dupuytren's disease: A model analysis

OBJECTIVE

To assess the cost of switching surgical aponeurectomy to percutaneous needle aponeurotomy in one-ray Dupuytren's disease.

METHODS

A model analysis was performed with a cross-sectional national survey of public and private French hospitals in 2012. All stays for one-ray aponeurectomy were "virtually" replaced with 1, 2 or 3 outpatient sessions of percutaneous needle aponeurotomy. The costs were based on the hospital cost (tariff per disease-related group) and on common classification of medical procedures performed in outpatient care for 2013.

RESULTS

Dupuytren's disease represented 18,707 hospitalizations (€26 million [2013 euros]) in France in 2012, 8534 hospitalizations for one-ray aponeurectomy (€11.9 million). By replacing surgical aponeurectomy with percutaneous needle aponeurotomy for one-ray Dupuytren's disease, 91% to 97% and 56% to 59% of the treatment costs could be saved using hospitalizations for one-ray aponeurectomy or total hospital costs, respectively, as reference.

CONCLUSIONS

Replacing aponeurectomy with percutaneous needle aponeurotomy for one-ray Dupuytren's disease could greatly reduce the treatment costs for all Dupuytren's disease. Effective alternatives to surgery for Dupuytren's disease, such as needle aponeurotomy in an outpatient setting should be considered in the economic perspective.

Epidemiological profile of Dupuytren's disease in Taiwan (Ethnic Chinese): a nationwide population-based study

BACKGROUND

The epidemiologic profile of ethnic Chinese patients with Dupuytren's disease is unknown. We therefore investigated the epidemiology of Dupuytren's disease using Taiwan's National Health Insurance Research Database.

METHODS

Patients who filed claims for treatment for Dupuytren's disease between January 2000 and December 2011 were identified in the database. Age- and gender-specific incidences were estimated by dividing the incidence number by population data.

RESULTS

We identified 1,078 patients with Dupuytren's disease (681 men, 397 women; male/female ratio: 1:1.72). The annual incidence rate ranged from 0.39-0.63/10(5) for men and 0.14-0.44/10(5) for women. A trend analysis revealed a rising trend in the annual incidence from 2001 to 2011 (p = 0.0199). The prevalence rate increased steadily from 0.46/10(5) in 2000 to 4.52/10(5) in 2011 (p = 0.0186). The mean age at onset was significantly higher in men than in women (60.7 ± 18.4 vs. 53.7 ± 15.5 years). Peak age at onset for men was 70-79 (28.1%) and for women was 50-59 (33.5%). Men > 60 years old had higher incidence rates than did women (incidence rate ratios: 2.0, 4.5, and 6.6 for those 60-69, 70-79, and ≥ 80, respectively). Hypertension (29.6%), diabetes mellitus (21.9%), hyperlipidemia (14.8%), ischemic heart disease (10.5%), and chronic obstructive pulmonary disease (8.0%) were the most common comorbidities.

CONCLUSIONS

The incidence and prevalence of Dupuytren's disease and the male/female ratio were significantly lower in ethnic Chinese than in Western ethnic groups. Moreover, the age at onset was significantly lower in ethnic Chinese women. However, the incidences of three comorbidities (hypertension, diabetes mellitus, and hyperlipidemia) were similar to those in other ethnicities.

Hospitalization for Dupuytren's disease: a French national descriptive analysis, 2002 to 2009

OBJECTIVES

The goal of this study is to describe hospitalization for treatment of Dupuytren's disease in France between 2002 and 2009.

METHODS

A repeated, annual, cross-sectional national survey of public and private French hospitals was performed between 2002 and 2009, with planned selection criteria for data extraction. Outcomes were age, sex, number of hospitalizations, length of stays, and types of surgical procedure. Types of surgical procedure included aponeurectomy, aponeurotomy, transplantation (skin graft), arthrolysis, amputation, arthrodesis, combined procedures.

RESULTS

The selected hospital stays represented 95% to 97% of all stays with Dupuytren's disease coded as the primary diagnosis. The hospitalizations involved mainly men in the 7th decade. The mean number of hospitalizations for Dupuytren's disease was 16,487, for between 7 and 8/10,000 total hospitalizations each year. Most of the hospitalizations for Dupuytren's disease were one-day stays in private settings. Over time, the mean length of hospital stay significantly shortened and the proportion of one-day stays significantly increased. Aponeurectomy was the most reported treatment. The distribution of aponeurectomy of 1 finger or ≥ 2 fingers was balanced. The performance of arthrolysis, transplantation, amputation and arthrodesis was low.

CONCLUSIONS

Despite of shortening of hospitals stays over time, hospitalization for surgery for Dupuytren's disease in France still represents a meaningful economic burden.

LEVEL OF EVIDENCE

Observational study II.

Use of resources and costs associated with the treatment of Dupuytren's contracture at an orthopedics and traumatology surgery department in Denia (Spain): collagenase clostridium hystolyticum versus subtotal fasciectomy

BACKGROUND

Our purpose was to analyze and compare the use of direct health resources and costs generated in the treatment of Dupuytren's contracture using two different techniques: subtotal fasciectomy and infiltration with Collagenase Clostridium Histolyticum (CCH) in regular clinical practice at the Orthopedic and Traumatology Surgery (OTS) Department at the Hospital de Denia (Spain).

METHODS

Observational, retrospective study based on data from the computerized clinical histories of two groups of patients- those treated surgically using a one or two digit subtotal fasciectomy technique (FSC) and those treated with CCH infiltration, monitored in regular clinical practice from February, 2009 to May, 2012. Demographic (age, sex), clinical (number of digits affected and which ones) and use of resources (hospitalizations, medical visits, tests and drugs) data were collected. Resource use and associated costs, according to the hospital's accounting department, were compared based on the type of treatment from Spain's National Health Service.

RESULTS

91 patients (48 (52.8%) in the FSC group) were identified. The average age and number of digits affected was 65.9 (9.2) years and 1.33 (0.48) digits affected in the FSC group, and 65.1 (9.7) years and 1.16 (0.4) digits in the CCH group.Overall, the costs of treating Dupuytren's disease with subtotal FSC amount to €1,814 for major ambulatory surgery and €1,961 with hospital stay including admission, surgical intervention (€904), examinations, dressings and physiotherapy. As to collagenase infiltration, costs amount to €952 (including minor surgery admission, vial with product, office examination and dressings). Finally, comparing total costs for treatments, a savings of €388 is estimated in favor of CCH treatment in the best-case scenario (patient under MAS system with no need for physiotherapy) and €1,008 in the worst-case scenario (patient admitted to hospital needing subsequent physiotherapy), implying a savings of 29% and 51%, respectively.

CONCLUSIONS

This study demonstrates that treating patients with DC by injection with CCH at the OTS department of the Hospital de Denia generates a total savings of 29% and 51% (€388 and €1008) compared with fasciectomy at the time of treatment. Long term evolution of CCH treatment is uncertain and the recurrence rate unknown.

Correction of contracture and recurrence rates of Dupuytren contracture following invasive treatment: the importance of clear definitions

PURPOSE

To call attention to the wide variety of definitions for recurrence that have been employed in studies of different invasive procedures for the treatment of Dupuytren contracture and how this important limitation has contributed to the wide range of reported results.

METHODS

This study reviewed definitions and rates of contracture correction and recurrence in patients undergoing invasive treatment of Dupuytren contracture. A literature search was carried out in January 2011 using the terms "Dupuytren" AND ("fasciectomy" OR "fasciotomy" OR "dermofasciectomy" OR "aponeurotomy" OR "aponeurectomy") and limited to studies in English.

RESULTS

The search returned 218 studies, of which 21 had definitions, quantitative results for contracture correction and recurrence, and a sample size of at least 20 patients. Definitions for correction of contracture and recurrence varied greatly among articles and were almost always qualitative. Percentages of patients who achieved correction of contracture (ie, responder rate) when evaluated at various times after completion of surgery ranged from 15% to 96% for fasciectomy/aponeurectomy. Responder rates were not reported for fasciotomy/aponeurotomy. Recurrence rates ranged from 12% to 73% for patients treated with fasciectomy/aponeurectomy and from 33% to 100% for fasciotomy/aponeurotomy. Review of these reports underscored the difficulty involved in comparing correction of contracture and recurrence rates for different surgical interventions because of differences in definition and duration of follow-up.

CONCLUSIONS

Clearly defined objective definitions for correction of contracture and for recurrence are needed for more meaningful comparisons of results achieved with different surgical interventions.

CLINICAL RELEVANCE

Recurrence after surgical intervention for Dupuytren contracture is common. This study, which evaluated reported rates of recurrence following surgical treatment of Dupuytren contracture, provides clinicians with practical information regarding expected long-term outcomes of surgical treatment choices.

TYPE OF STUDY/LEVEL OF EVIDENCE

Economic and decision analysis III.

Clostridium histolyticum collagenase in the treatment of Dupuytren's contracture

Dupuytren's disease is a common, costly and recurrent health issue. This review compares Clostridium histolyticum collagenase with current operative treatments. Collagenase management is an effective non-surgical alternative associated with lower risks of serious adverse events, but higher incidence of non-serious adverse events.

Current trends in the surgical management of Dupuytren's disease in Europe: an analysis of patient charts

INTRODUCTION: Dupuytren's disease (DD) causes progressive digital flexion contracture and is more common in men of European descent. METHODS: Orthopaedic and plastic surgeons in 12 European countries (the Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, The Netherlands, Poland, Spain, Sweden and the UK) with >3 and <30 years experience reviewed the medical charts of five consecutive patients they had treated surgically for DD in 2008. Descriptive statistics are reported. RESULTS: In total, 3,357 patient charts were reviewed. Mean (standard deviation) patient age was 61.9 (10.2) years; 81% were men. At the time of the procedure, 11% of patients were at Tubiana stage Ia (0-20° total flexion); 30%, stage Ib (21-45°); 34%, stage II (46-90°); 17%, stage III (91-135°); and 5%, stage IV (>135°). Percutaneous needle fasciotomy was performed in 10%, fasciotomy in 13%, fasciectomy in 69% and dermofasciectomy (DF) in 6% of patients. After surgery, fingers improved a mean of 1.9 Tubiana stages, and 54% of patients had no nodules or contracture. The rate of reported complications during the procedure was 4% overall (11% in patients undergoing DF). The most common postoperative complications reported were haematoma (8%), wound healing complications (6%) and pain (6%). No postoperative complications were reported in 77% of patients. CONCLUSIONS: In this European study of more than 3,000 patients with DD, most patients were diagnosed at Tubiana stage I or II, the majority received fasciectomy and more than half had no nodules or contracture remaining after surgery. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12570-012-0092-z) contains supplementary material, which is available to authorized users.

Current trends in the surgical management of Dupuytren's disease in Europe: the surgeon's perspective

INTRODUCTION: Dupuytren's disease (DD), commonly affecting European men, is generally treated with surgery. METHODS: Orthopaedic and plastic surgeons who had been practicing for >3 and <30 years and operated on ≥5 patients with DD between September and December 2008 were surveyed in 12 European countries (Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, The Netherlands, Poland, Spain, Sweden and UK). The survey assessed procedures performed, factors influencing choice of procedure, use of physical therapy and recurrence. Descriptive statistics are reported. RESULTS: A total of 687 surgeons participated, including 579 orthopaedic and 108 plastic surgeons; 383 (56%) were hand surgeons. About 37% of surgeons performed percutaneous needle fasciotomy (PNF), 77% fasciotomy, 95% fasciectomy and 40% dermofasciectomy (DF). Surgeons' choice of procedure was influenced by patient preferences, age, degree of contracture and recurrent disease. The percentage of surgeons prescribing physical therapy and the mean (standard deviation [SD]) duration of therapy increased with procedure complexity: PNF = 82%, 5.2 (3.9) weeks; fasciotomy = 94%, 5.3 (3.6); fasciectomy = 97%, 6.7 (5.1); and DF = 99%, 8.5 (6.4). Using survey responses, mean (SD) estimated recurrence rates decreased and estimated time to recurrence increased with procedure complexity-PNF = 44% (27%), 17 (15) months; fasciotomy = 30% (24%), 20 (18); fasciectomy = 20% (17%), 29 (23); and DF = 20% (19%), 33 (27). CONCLUSIONS: Across Europe, patient and surgical factors influence the intention to use a surgical procedure. Fasciectomy was the most commonly performed procedure type and was associated with lower recurrence than PNF or fasciotomy. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12570-012-0091-0) contains supplementary material, which is available to authorized users.

Postoperative management of Dupuytren's disease with topical nitroglycerin

Dupuytren's contracture remains a significant clinical challenge due to associated complications and a recurrence rate of up to 60%. Commonly, the operated skin tends to rebuild scar in the area of surgery. Assuming local ischemia as an etiological factor, two cases in which topical nitroglycerin was used following surgical treatment of Dupuytren's disease are presented. In these patients, no raised scar formation developed during healing. At least six months after surgery, disease recurrence was not noted and the patients and surgeon reported improved skin quality. In the present study, the use of topical nitroglycerin, a local vasodilator, appeared to prevent recurrent scar formation, possibly through prevention of local ischemia. Further study and follow-up is necessary.

Direct and indirect costs associated with Dupuytren's contracture

OBJECTIVE

To compare direct (medical and drug) and indirect (work loss) costs between privately insured US employees with Dupuytren's contracture (DC) and demographically matched controls without DC.

METHODS

Employees aged 18-64 with ≥ 1 DC diagnosis (ICD-9-CM: 728.6, 718.44) with service dates 1/1/2000-3/31/2009 were selected from a de-identified, privately insured claims database (n∼3,000,000). The index date was defined as the most recent DC diagnosis with continuous eligibility for 6 months prior (baseline period) and 1 year after (study period) diagnosis. Employees with DC were matched 1:1 on age, region, gender, and index date to controls without DC, Peyronie's, or Ledderhose disease diagnoses in their claims histories. Descriptive analyses compared demographic characteristics, comorbidities, resource utilization, direct costs, and indirect costs inflated to 2009 dollars.

RESULTS

DC employees (n=1406, mean age 49 years) with matched controls met the inclusion criteria. DC employees compared with controls had significantly (all p<0.05) higher baseline comorbidities, including hyperlipidemia (21.1% vs 15.6%), hypothyroidism (3.5% vs 2.0%), cancer (3.1% vs 1.5%), and diabetes (8.1% vs 3.6%). During the study period, DC employees had significantly (all p<0.01) higher rates of inpatient stays (7.7% vs 5.3%), emergency department visits (19.8% vs 13.9%), outpatient visits (100.0% vs 78.4%), physical therapy visits (30.2% vs 7.2%), and any prescription use (85.0% vs 69.2%), as well as higher mean work loss days (14.2 vs 7.3). DC employees had on average significantly (all p<0.01) higher annual direct costs ($5974 vs $3175), indirect costs ($2737 vs $1309), and total costs ($8712 vs $4485) compared with controls during the study period.

LIMITATIONS

Findings did not account for lost productivity at work and were based on a privately insured, employed population, which may not be generalizable to all DC patients.

CONCLUSIONS

Employees with DC had substantially higher comorbidity rates, utilization, and direct and indirect costs compared with demographically matched controls.

Dupuytren's contracture: a retrospective database analysis to assess clinical management and costs in England

Background

Dupuytren's disease is a fibro-proliferative disorder affecting ~3-5% of the UK population. Current surgical treatments for Dupuytren's contracture (DC) include fasciectomy and fasciotomy. We assessed the clinical management of DC in England over a 5-year period; associated NHS costs were assessed for a 1-year period.

Methods

Hospital Episode Statistics were extracted from April 2003 to March 2008 for patients with Palmar Fascial Fibromatosis (ICD10 = M720) and DC-related procedures. Variables included demographics, OPCS, patient status and physician specialty. To estimate 2010-2011 costs, HRG4 codes and the National Schedule of Tariff 2010-11-NHS Trusts were applied to the 2007-2008 period.

Results

Over 5 years, 75,157 DC admissions were recorded; 64,506 were analyzed. Mean admissions per year were 12,901 and stable. Day cases increased from 42% (2003-2004) to 62% (2007-2008). The percent of patients having two or more admissions per year increased from 5.5% in 2003-2004 to 26.1% in 2007-2008. Between 2003 and 2007, 91% of procedures were Fasciectomy. Revision of Fasciectomy and Fasciotomy each accounted for ~4%; Amputation for 1%. In 2007, classification was extended to identify Digital Fasciectomy, its Revision and Dermofasciectomy. In 2007-2008, admissions were: 70% Palmar Fasciectomy, 16% Digital Fasciectomy, 1.3% Other Fasciectomy, 4.4% Revision of Palmar Fasciectomy, 1.3% Revision of Digital Fasciectomy, 3.8% Division of Palmar Fascia, 2.6% Dermofasciectomy and 1.1% Amputation. 79% of cases were overseen by trauma and orthopaedic surgeons, 19% by plastic surgeons. Mean (±SD) inpatient hospital length of stay was 1.5 (±1.4) days in 2003-2004 and 1.0 (±1.3) days in 2007-2008. Total estimated costs for 1 year (2010-2011) were £41,576,141. Per-patient costs were £2,885 (day case) and £3,534 (inpatient). Costs ranged from £2,736 (day-case Fasciectomy) to £9,210 (day-case Revision Digital).

Conclusions

Between 2003 and 2008, fasciectomy was the most common surgical procedure for DC in England. While procedure rates and physician specialties varied little, there was a reversal in surgical venue: inpatient operations decreased as day-case procedures increased. The change is likely due to economic trends and changes to the healthcare system. Estimated costs for 2010-2011 varied by procedure type and patient status. These findings can be used to understand clinical management of DC and guide healthcare policy.

The Wide-Awake Approach to Dupuytren's Disease: Fasciectomy under Local Anesthetic with Epinephrine

The Wide-Awake Approach to Dupuytren's contracture involves fasciectomy under local anesthetic with epinephrine and no tourniquet. The goal of this study is to show that the Wide-Awake Approach produces equivalent outcomes to fasciectomy under general anesthetic with a tourniquet, with fewer risks to the patient. A multicenter retrospective review was conducted on 111 patients with fasciectomies under local or general anesthetic between 2001 and 2007. Data on patient demographics, comorbidities, cost, as well as range of motion was collected and evaluated using Microsoft Excel and SAS. Of 148 fingers, 102 were treated under local and 46 under general anesthetic. The average postoperative Total Active Motion (TAM) for general anesthetic patients was 199.0 ± 29.6 (D5), 223.9 ± 29.3 (D4), 234.6 ± 14.6 (D3), and 246.7 ± 14.4 (D2). The average postoperative TAM for local anesthetic patients was 168.3 ± 62.2 (D5), 195.9 ± 67.5 (D4), 173.0 ± 72.6 (D3), and 177.5 ± 31.8 (D2). There were no significant differences between any of these individual groups (p = 0.09, 0.26, 0.12, and 0.20, respectively); however, when pooled, the overall TAM was significantly greater in the general anesthesia group (222.0 ± 29.7 vs. 186.0 ± 63.0, p = 0.002.). Complication rates and types were similar with both techniques. The Wide-Awake Approach to Dupuytren's contracture avoids general anesthetic risks and has cost benefits to healthcare providers. Although it yields similar range of motion outcomes to fasciectomy performed under general anesthesia, total active motion may be better with fasciectomy done under general anesthesia.

Epidemiological evaluation of Dupuytren's disease incidence and prevalence rates in relation to etiology

Dupuytren's Disease (DD) is a common, fibroproliferative disorder affecting the palmar surface of the hands which is often irreversible and progressive. Understanding the epidemiology of DD is important in order to provide clues to its etiopathogenesis. This review aims to evaluate the epidemiological studies carried out in DD since 1951. Studies evaluating the epidemiology of DD were searched using Medline, Pubmed, and Scopus which dated back from 1951 to current date. Inclusion criteria were any studies investigating the prevalence or incidence of DD in any population group. A total of 620 articles were cited. Forty-nine studies were subsequently identified as relevant to evaluating the epidemiology of DD. The prevalence of DD in all studies increased with age with a male to female ratio of approximately 5.9:1. Prevalence rates ranged from 0.2% to 56% in varying age, population groups, and methods of data collection. The highest prevalence rate was reported in a study group of epileptic patients. Although, only one study calculated the incidence (as opposed to prevalence) of DD to be equal to 34.3 per 100,000 men (0.03%). In conclusion, the prevalence of DD in different geographical locations is extremely variable, and it is not clear whether this is genetic, environmental, or a combination of both. The majority of the prevalence studies have been conducted in Scandinavia or the UK, and the vast changes in population structure, the changes in prevalence of associated diseases, and the change in diagnostic criteria of DD makes understanding the epidemiology of this condition difficult.