Agreement between oral contraceptive users and prescribers: implications for case-control studies

Case-control studies examining the effects of oral contraceptives (OC) are prone to misclassification bias due to errors in assessment of OC use. Concern about inaccurate exposure histories has increased since current studies require women to recall OC use over prolonged periods of time. In preparation for a case-control study of breast cancer and OC use, an investigation was carried out to assess agreement between women's lifetime histories of OC use (covering a period of up to 20 years) and prescribers' records. OC histories were obtained during personal interview with 218 women who had used OC at some point in their lives (127 breast cancer patients, 91 controls). Recall was aided by an album with color photographs of all OC marketed in the Netherlands from 1962 onwards (n = 65), and a calendar that covered the women's life span from date of birth to menopause. The participants were asked for the names of all physicians who prescribed OC for them. The rate of response from the prescribers was high (94%), but only half of the forms provided useful information. Patient-prescriber agreement on brand names (including dosage) was 70%. About half of the women agreed with their prescribers on starting dates to within less than a year's difference. Approximately the same percentage of agreement was found for stopping dates. Multiple linear regression indicated that agreement on brand names and dates of usage was lower for women of low socioeconomic status, for healthy women (as compared to breast cancer patients) and for periods of pill use that had to be recalled from the more distant past. Agreement on total duration of use was high enough to permit testing of a moderately strong duration-response relationship in a case-control study

Validation of quantitative salivary gland scintigraphy in relation to the American-European concensus criteria for Sjögren's syndrome

Purpose The aim of this retrospective study was to evaluate the diagnostic value of semiquantitative parameters in salivary gland scintigraphy (SGS) in the diagnostic work-up of primary Sjögren's Syndrome (SS) using the American-European consensus criteria (AECC) as the gold standard. Patients and methods 99mTc-pertechnetate-SGS was performed in 110 patients with suspected primary SS. Uptake ratios (URs) and excretion fractions (EFs) for all parotid and submandibular salivary glands were calculated. Patients were divided into SS-positive, SS-negative, and SS-equivocal groups on the basis of the AECC criteria. SGS semiquantitative parameters were compared per group and cut-off values were defined. Results Ninety-six (87%) women and 14 (13%) men with a mean age of 51 years (range: 18-77 years) were included. All patients underwent SGS, labial biopsy, Schirmer's test, and antibody tests (anti-SS-A and anti-SS-B). Twenty-four patients were SS positive, 56 patients were SS negative, and 30 patients were SS-equivocal. UR of the parotid glands did not differ between SS-positive and SS-negative groups [mean (range): 3.4 (1.4-6.9) and 3.9 (2.2-6.5), respectively], whereas UR of the submandibular glands were significantly lower in SS-positive patients [mean (range): 2.7 (1.1-5.6) and 3.5 (2.3-5.3), respectively]. EF in both parotid and submandibular glands was significantly lower in SS-positive patients compared with SS-negative patients: parotid 24% (range:-4 to 53%) and 36% (range: 15-58%), respectively; submandibular 16% (range:-5 to 46%) and 29% (range: 9-49%), respectively. On the basis of a cut-off value of 2.0 for UR and 20% for EF, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.67, 0.86, 86, and 67%, respectively. Of 30 SS-equivocal patients, 15 had a positive SGS, whereas the other 15 were SGS negative. In both, there was no correlation with the AECC criteria IV (histopathology) and VI (antibodies). In these cases, the SGS result was decisive. Conclusion Quantitative SGS is a valuable tool in the diagnostic management of patients with suspected primary SS, especially in those in whom the nonscintigraphic AECC criteria are not conclusive. The straightforward quantitative analysis of SGS used in this study can be implemented in any nuclear medicine department

Validation of quantitative salivary gland scintigraphy in relation to the American-European concensus criteria for Sjögren's syndrome

Purpose The aim of this retrospective study was to evaluate the diagnostic value of semiquantitative parameters in salivary gland scintigraphy (SGS) in the diagnostic work-up of primary Sjögren's Syndrome (SS) using the American-European consensus criteria (AECC) as the gold standard. Patients and methods 99mTc-pertechnetate-SGS was performed in 110 patients with suspected primary SS. Uptake ratios (URs) and excretion fractions (EFs) for all parotid and submandibular salivary glands were calculated. Patients were divided into SS-positive, SS-negative, and SS-equivocal groups on the basis of the AECC criteria. SGS semiquantitative parameters were compared per group and cut-off values were defined. Results Ninety-six (87%) women and 14 (13%) men with a mean age of 51 years (range: 18-77 years) were included. All patients underwent SGS, labial biopsy, Schirmer's test, and antibody tests (anti-SS-A and anti-SS-B). Twenty-four patients were SS positive, 56 patients were SS negative, and 30 patients were SS-equivocal. UR of the parotid glands did not differ between SS-positive and SS-negative groups [mean (range): 3.4 (1.4-6.9) and 3.9 (2.2-6.5), respectively], whereas UR of the submandibular glands were significantly lower in SS-positive patients [mean (range): 2.7 (1.1-5.6) and 3.5 (2.3-5.3), respectively]. EF in both parotid and submandibular glands was significantly lower in SS-positive patients compared with SS-negative patients: parotid 24% (range:-4 to 53%) and 36% (range: 15-58%), respectively; submandibular 16% (range:-5 to 46%) and 29% (range: 9-49%), respectively. On the basis of a cut-off value of 2.0 for UR and 20% for EF, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.67, 0.86, 86, and 67%, respectively. Of 30 SS-equivocal patients, 15 had a positive SGS, whereas the other 15 were SGS negative. In both, there was no correlation with the AECC criteria IV (histopathology) and VI (antibodies). In these cases, the SGS result was decisive. Conclusion Quantitative SGS is a valuable tool in the diagnostic management of patients with suspected primary SS, especially in those in whom the nonscintigraphic AECC criteria are not conclusive. The straightforward quantitative analysis of SGS used in this study can be implemented in any nuclear medicine department