Differential case reporting in a national clinical quality database: an analysis of the impact on comparison of outcome between departments.

INTRODUCTION: Selection biases due to difference in reporting may cause spurious findings. The purpose of this study was to illustrate the effect of case incompleteness on the differences in 180-day survival rate when comparing departments. METHODS: Completeness was estimated as the proportion of patients reported to the Danish Lymphoma Database compared with the National Patient Registry. The effect of differential reporting between departments was investigated using plots were the proportion of patients who survived 180 days in the individual departments were compared with the national average as well as examining the association between the department and 180-day survival. RESULTS: In total, 8015 patients were registered in the National Patient Registry with a lymphoma diagnosis. Of these, 1824 patients were not reported to the Danish Lymphoma database equaling a rate of completion of 77.2%. There were large differences between departments with regard to patient completeness (range, 52.4%-91.6%). The survival of the patients reported to the database was significantly better than those not reported and the differential reporting affected the department ranking. CONCLUSION: Differential case reporting may cause spurious findings. To ensure valid conclusions validation against a gold standard and continuous feedback to data providers is important.

Socioeconomic factors may influence the surgical technique for benign hysterectomy.

INTRODUCTION: Owing to significantly improved outcomes, vaginal hysterectomy is the recommended standard approach when feasible in preference to abdominal hysterectomy. It is, however, not clear whether the use of vaginal hysterectomy varies with the women's socioeconomic background. MATERIAL AND METHODS: All 22,150 women registered in the Danish Hysterectomy Database in the 2004-2008-period were included in this cohort study and linked to central registers providing information on education, income and employment. Analyses were carried out using multiple logistic regression models. RESULTS: Among the 16,645 patients with information on all variables, 34% had a vaginal hysterectomy, while 60% had an abdominal and 6% a laparoscopic procedure. Women with a short education were more likely to undergo vaginal hysterectomy (30%) than women with a higher education (28%) (odds ratio (OR): 1.23; 95% confidence interval (CI): 1.10-1.38), but this association seemed to be fully explained by differences in surgery indication (OR: 0.99; CI: 0.87-1.13). Women out of work less often had a vaginal hysterectomy than women in work when adjusting for surgery indication (OR: 0.79; CI: 0.70-0.88). CONCLUSION: Small socioeconomic differences in surgical approach in hysterectomy were observed and were seemingly explained by clinical surgery indications, with the exception of women out of work for whom vaginal hysterectomy is used less often.