Cost-effectiveness of screening for hypo- and hyperthyroidism in India

Radioiodine or surgery for toxic thyroid adenoma: dissecting an important decision. A cost-effectiveness analysis

OBJECTIVE

To examine the cost effectiveness of therapeutic strategies for toxic thyroid adenoma.

DESIGN

Markov state transition decision analytic model.

SETTING

Ambulatory and inpatient.

PATIENTS

Hypothetical cohort of 40- year-old women with toxic thyroid adenomas. Patient age was varied in sensitivity analyses. Data on the prevalence of coincident thyroid cancer, complications, and treatment efficacies were derived from a systematic review of the literature.

INTERVENTIONS

Thyroid lobectomy after a 3 month-course of antithyroid drugs (ATDs), high-dose (<555 MBq) radioactive iodine (RAI), low-dose (>555 MBq) RAI, and lifelong ATDs.

MEASUREMENTS AND MAIN RESULTS

Outcomes were measured in quality-adjusted life years (QALYs). Costs were estimated from the health care system perspective. Future costs and effectiveness were discounted at 3% per year. For a 40- year-old woman, surgery was the most effective, while low-dose RAI was the least costly. The marginal cost-effectiveness of surgery versus low-dose RAI was $13,183 per QALY. Surgery was less costly and more effective than lifelong ATDs. RAI was more effective than surgery if surgical mortality exceeded 0.90% (base-case 0.001%). Surgery provided relatively inexpensive gains (<$50,000 per QALY) in quality-adjusted life expectancy in patients less than 74 years of age.

CONCLUSIONS

For most patients less than 60 years of age, surgery is an effective strategy with a reasonable cost. However, for any given patient, surgical mortality, therapeutic costs and preference must be considered in choosing an appropriate therapy.

The epidemiology of hypothyroidism--an update

Comparison of studies of the prevalence and incidence of hypothyroidism is hampered by differing definitions and population samples. Using a uniform set of diagnostic criteria, the prevalence of previously undiagnosed, spontaneous, overt hypothyroidism in community-based studies has been estimated between 2-4/1000 total population world-wide. If all cases of previously diagnosed hypothyroidism, previous thyroid surgery and radioiodine treatment are included, this prevalence rises to approximately 10/1000, and if subclinical cases are included, then the prevalence is probably over 50/1000 total population. The annual incidence of overt hypothyroidism is between 1-2/1000 for female and around 2/10,000 for males, with individuals having previously elevated TSH and positive circulating thyroid autoantibodies, being particularly at risk. The question of widespread population screening for hypothyroidism is unsettled, but it is probably not cost-effective unless incorporated as part of a screening programme for other conditions such as cervical cancer, or targeted at high risk groups such as post-menopausal women. The combination of serum TSH estimation and a high clinical index of suspicion should detect most patients with thyroid dysfunction, although detailed studies on the use of the more sensitive assays in the detection of both hyper- and hypothyroidism have yet to be published.

Intermediate, indeterminate, and uninterpretable diagnostic test results

Diagnostic tests do not always yield positive or negative results; sometimes the results are intermediate, indeterminate, or uninterpretable. No consensus exists for the incorporation of such results into data assessment. Conventional Bayesian analysis leads investigators to either exclude patients with non-positive, non-negative results from their studies or categorize such results into inappropriate cells of the standard four-cell decision matrix. The authors propose a standardized method for reporting results in studies dealing with diagnostic test use and discuss how researchers should expand the four-cell matrix to six cells when non-positive, non-negative results occur. They suggest that the six-cell matrix with new operational definitions of sensitivity, specificity, likelihood ratios, and test yield should be adopted routinely. In addition, they define the different types of non-positive, non-negative results and demonstrate how clinicians can use tree-structured decision analysis from the six-cell matrix. While their method does not solve all problems posed by non-positive, non-negative results, it does suggest a standard method for reporting these results and utilizing all the data in decision making.