Thanks to Robin Ess for the easy to read chart!
Abstract
Objective Cushing’s disease (CD) is a rare endocrine disorder characterized by excess secretion of ACTH due to a pituitary adenoma. Current treatment options are limited and may pose additional risks. A literature review was conducted to assess the holistic burden of CD.
Design Studies published in English were evaluated to address questions regarding the epidemiology of CD, time to diagnosis, health-related quality of life (HRQoL), treatment outcomes, mortality, prevalence of comorbidities at diagnosis, and reversibility of comorbidities following the treatment.
Methods A two-stage literature search was performed in Medline, EMBASE, and Science Citation Index, using keywords related to the epidemiology, treatment, and outcomes of CD: i) articles published from 2000 to 2012 were identified and ii) an additional hand search (all years) was conducted on the basis of bibliography of identified articles.
Results At the time of diagnosis, 58–85% of patients have hypertension, 32–41% are obese, 20–47% have diabetes mellitus, 50–81% have major depression, 31–50% have osteoporosis, and 38–71% have dyslipidemia. Remission rates following transsphenoidal surgery (TSS) are high when performed by expert pituitary surgeons (rates of 65–90%), but the potential for relapse remains (rates of 5–36%). Although some complications can be partially reversed, time to reversal can take years. The HRQoL of patients with CD also remains severely compromised after remission.
Conclusions These findings highlight the significant burden associated with CD. As current treatment options may not fully reverse the burden of chronic hypercortisolism, there is a need for both improved diagnostic tools to reduce the time to diagnosis and effective therapy, particularly a targeted medical therapy.
Introduction
Cushing’s disease (CD) is a rare condition caused by a pituitary adenoma that secretes excess ACTH (1), which promotes excess cortisol production from the adrenal glands. Excess cortisol induces a clinical phenotype that harbors all components of the metabolic syndrome, such as central obesity, diabetes mellitus, dyslipidemia, and hypertension, as well as muscle weakness, hirsutism, increased bruisability, psychological dysfunction, and osteoporosis (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11).
Patients with CD experience a significant clinical burden due to comorbidities, increased mortality, and impaired health-related quality of life (HRQoL) due to prolonged exposure to elevated cortisol levels (3, 5, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20). In particular, patients with CD often experience severe fatigue and weakness, physical changes, emotional instability, depression, and cognitive impairments, which have a profound impact on daily life (13, 21).
Although there have been several consensus statements published recently on the definition of remission, diagnosis, and the management of CD, the severity and diversity of the clinical scenario and associated morbidities continue to present a management challenge (1, 22, 23). Additionally, there is recent evidence of persistent deleterious effects after remission, most notably persistent elevated cardiovascular risk (3, 22). The main objective of the current literature review is to describe the current burden of the disease and to summarize data on specific aspects of this burden, which underscores the need for improved diagnostic and therapeutic approaches.
Materials and methods
Available literature were evaluated to address questions regarding the epidemiology of CD, time to diagnosis, mortality, prevalence of comorbidities at diagnosis, reversibility of comorbidities after treatment (in particular, after disease remission), outcomes and complications of current treatment options, and HRQoL associated with CD and interventions.
The literature search was performed in Medline, EMBASE, and Science Citation Index, using keywords related to the epidemiology, treatment, and outcomes of CD. It was conducted in two stages: i) articles published between 2000 and 2012 were identified through a PubMed search using the following keywords: CD, incidence, prevalence, mortality, treatment, remission, cure, excess cortisol, outcomes, cost, QoL, morbidities, transsphenoidal surgery (TSS), adrenalectomy, radiotherapy, steroidogenesis inhibitors, ketoconazole, mitotane, aminoglutethimide, etomidate, metyrapone, pasireotide, and cortisol receptor antagonists; and ii) an additional hand search was conducted on the basis of the bibliographies of identified articles. All studies that provided data (regardless of publication year) related to these research questions were retained.
Definitions
Different criteria for defining the remission of hypercortisolism have been proposed, ranging from the occurrence of definitive or transient postoperative hypocortisolemia to the adequate suppression of cortisol after dexamethasone administration. According to a recent consensus statement (23), persistent postoperative morning serum cortisol levels of <2 μg/dl (∼50 nmol/l) are associated with remission and a low recurrence rate of ∼10% at 10 years. Persistent serum cortisol levels above 5 μg/dl (∼140 nmol/l) for up to 6 weeks following surgery require further evaluation. When serum cortisol levels are between 2 and 5 μg/dl, the patient can be considered in remission and can be observed without additional treatment for CD. A subset of patients can even develop complete adrenal insufficiency (serum cortisol levels below 2 μg/dl (∼50 nmol/l)) up to 12 weeks postsurgery (24, 25). Therefore, repeated evaluation in the early postoperative period is recommended. However, long-term follow-up is necessary for all patients because no single cortisol cutoff value excludes those who later experience disease recurrence, and up to 25% of patients develop a recurrent adenoma within 10 years after surgery (26, 27, 28).
Results
Incidence and prevalence of CD
Although epidemiologic data on CD are limited, several population-based studies indicate an incidence of 1.2–2.4 per million (14, 19) and the prevalence of diagnosed cases to be ∼39 per million population (14). Lindholm et al. (19) used the case definition as either the presence of a corticotroph adenoma or remission after neurosurgery, which yielded an estimated incidence rate of 1.2–1.7 per million per year. Etxabe & Vazquez (14) reported an incidence of 2.4 per million in Vizcaya, Spain. A large-scale retrospective survey carried out in New Zealand by Bolland et al. (29) found the approximate prevalence of all forms of Cushing’s syndrome (CS) (the majority of these cases were of pituitary origin) to be 79 per million and the incidence to be 1.8 per million per year. Differences in epidemiologic estimates may be attributable to varying case definitions (for instance, the study by Lindholm excluded cases in which the adenoma could not be localized or those that could not achieve remission from surgery), geographical differences, and temporal effects. The prevalence of CD may be underestimated due to unrecognized patients with mild symptoms and patients with a cyclic form of CD (30).
Time to diagnosis
Data on the time from onset of symptoms to diagnosis are also limited. In a prospective study by Flitsch et al. (31) of 48 patients with pituitary adenomas, including 19 who had ACTH-secreting adenomas causing CD, the reported time from onset of symptoms to diagnosis was 4.3 years. A study by Martinez Ruiz et al. (32), which was based on only four pediatric CD patients, reported the time between onset of symptoms and diagnosis as ranging from 2.5 to 5 years. Etxabe & Vazquez (14) estimated that the average time from onset of clinical symptoms to diagnosis in 49 CD patients was 45.8±2.7 months (6–144 months), thus 3.8 years. This is corroborated by the findings from a Belgian cross-sectional study on pituitary adenomas including CD, which estimated that patients experienced symptoms for an average of 45 months before diagnosis (33). However, the reliability and generalizability of these data are limited by small sample sizes and the retrospective nature of the studies. Indeed, the New Zealand data from Bolland et al. (29) report that on presentation, patients experienced symptoms for a median of 2.0 years (but ranging up to 20 years) before diagnosis. On the basis of data from the prospective European Registry on Cushing’s syndrome (ERCUSYN) (total number of patients=481, of whom 66% of patients had CD), median delay in diagnosis was 2 years (34).
Mortality in patients with CD
Mortality in patients with CD has been analyzed in several small studies, with overall rates reported as standardized mortality ratio (SMR) ranging from 1.7 to 4.8 (Table 1) (14, 15, 17, 19). In studies in which mortality was assessed among those in remission and those with persistent disease separately, patients with persistent hypercortisolemia consistently had the highest mortality risk (15, 19, 35, 36). In addition, TSS as a first-line treatment has been an important advance as high remission rates after initial surgery have been accompanied by mortality rates that mirror those observed in the general population (17, 35, 37). In a case series from the UK, it was found that the majority of deaths occurred before 1985, which was before TSS was employed as the routine first-line treatment at the center (36). In a recent retrospective study, 80 patients undergoing TSS for CD between 1988 and 2009 were evaluated, and long-term cure (defined as ongoing absence of hypercortisolism at last follow-up) was reported in 72% of patients. However, overall elevated mortality persisted in patients (SMR 3.17 (95% CI: 1.70–5.43)), including those who achieved ‘cure’ (SMR 2.47 (95% CI: 0.80–5.77)), although even higher mortality was seen in those with postoperative recurrence/persistent disease (SMR 4.12 (95% CI: 1.12–10.54) (38). Additionally, a nationwide, retrospective study in New Zealand reported significant persistently increased mortality both in macro- and microadenomas (SMR 3.5 (1.3–7.8) and 3.2 (2.0–4.8) respectively), despite long-term biochemical remission rates of 93 and 91% of patients, respectively (29).
Read more at http://m.eje-online.org/content/167/3/311.full
Filed under: Cushing's, pituitary, Rare Diseases, symptoms, Treatments | Tagged: abstract, ACTH, Cushing's Disease, depression, diabetes mellitus, dyslipidemia, Endocrine Disorders, hypertension, obese, pituitary, quality of life, transsphenoidal | Leave a comment »
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