Table 7.
Quality of Evidence
| Outcome | No. of studies study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Quality of evidence | Main findings | |
|---|---|---|---|---|---|---|---|---|
| Key Question 1: Active surveillance vs. immediate surgery, low-risk differentiated thyroid cancer <2 cm | All-cause mortality | 3 cohort studies (N = 2982) 7 uncontrolled treatment series or active surveillance (N = 1219) |
High | Consistent | Direct | Precise | Low | Cohort studies: 0.3% vs. 0.5% (1 study); no cases (2 studies) Treatment series: No cases (7 studies) |
| Thyroid cancer mortality | 4 cohort studies (N = 4377) 7 uncontrolled treatment series of active surveillance (N = 1219) |
High | Consistent | Direct | Precise | Low | Cohort studies: 0% vs. 0.2% (1 study); no cases (3 studies) Treatment series: No cases (6 studies) |
|
| Recurrence after surgery | 3 cohort studies (N = 2574) 4 uncontrolled treatment series of active surveillance (N = 80) |
High | Consistent | Direct | Precise | Low | Cohort studies: 0% vs. 3.0%, 1.1% vs. 0.5%, and 0% vs. 2.4% (3 studies) Treatment series: No cases (3 studies) |
|
| Lymph node metastasis | 3 cohort studies (N = 2574) 5 uncontrolled treatment series of active surveillance (N = 1004) |
High | Consistent | Direct | Precise | Low | Cohort studies: 0.1% vs. 0.3%, 0.8% (T1a) and 3.3% (T1b) vs. 1.5% (T1b), and 0% vs. 5.6% (3 studies) Treatment series: Range 0% to 2.9% (5 studies) |
|
| Distant metastasis | 4 cohort studies (N = 4388) 4 uncontrolled treatment series of active surveillance (N = 946) |
High | Consistent | Direct | Precise | Low | Cohort studies: 0% vs. 0.3% (1 study); no cases (3 studies) Treatment series: No cases (4 studies) |
|
| Tumor growth ≥3 mm in persons undergoing active surveillance | 4 cohort studies (N = 2026) 6 uncontrolled treatment series of active surveillance (N = 996) |
High | Inconsistent | Direct | Precise | Low | Cohort studies: Range 1.4% to 7.5% (4 studies) Treatment series: Range 2.1% to 20% (6 studies) |
|
| Subsequent surgery in persons undergoing active surveillance | 4 cohort studies (N = 2160) 7 uncontrolled treatment series of active surveillance (N = 1240) |
High | Inconsistent | Direct | Precise | Low | Cohort studies: Range 2.6% to 32% (4 studies) Uncontrolled treatment series: 3.5% to 23% (7 studies) |
|
| Temporary vocal cord paralysis, temporary hypoparathyroidism, thyroid replacement | 1 cohort study (n = 1179) | High | Unable to determine | Direct | Precise | Low | Temporary vocal cord paralysis: 0.6% vs. 4.1% (1 cohort study) Temporary hypoparathyroidism: 2.8% vs. 16.7% (1 cohort study) Thyroid replacement: 20.7% vs. 66.1% (1 cohort study) |
|
| Key Question 2: Nonsurgical management vs. surgery, differentiated thyroid cancer | Mortality or thyroid cancer mortality | 4 cohort studies (N = 88,654) | Moderate | Inconsistent | Indirecta | Precise | Low | Surgery associated with decreased risk of all-cause mortality (1 study) and thyroid cancer mortality (1 study) vs. nonsurgical therapy in older (>65 or >75 years) persons with differentiated thyroid carcinoma (not restricted to low-risk tumors); surgery associated with decreased risk of all-cause mortality for high-risk but not low-risk tumors (1 study); no difference in thyroid cancer mortality in younger persons with low-risk cancers <4 cm (1 study) |
a
Downgraded due to serious indirectness for evaluation of active surveillance.