A method for clustering surgical cases to allow master surgical scheduling

Master surgical scheduling can improve manageability and efficiency of operating room departments. This approach cyclically executes a master surgical schedule of surgery types. These surgery types need to be constructed with low variability to be efficient. Each surgery type is scheduled based upon its frequency per cycle. Surgery types that cannot be scheduled repetitively are put together in so-called dummy surgeries. Narrow defined surgery types, with low variability, lead to a large volume of such dummy surgeries that reduce the benefits of a master surgical scheduling approach. In this paper we propose a method, based on Ward's hierarchical cluster method, to obtain surgery types that minimizes the weighted sum of the dummy surgery volume and the variability in resource demand of surgery types. The resulting surgery types (clusters) are thus based on logical features and can be used in master surgical scheduling. The approach is successfully tested on a case study in a regional hospital

How baseline, new-onset, and persistent depressive symptoms are associated with cardiovascular and non-cardiovascular mortality in incident patients on chronic dialysis

AbstractObjectiveDepressive symptoms are associated with mortality among patients on chronic dialysis therapy. It is currently unknown how different courses of depressive symptoms are associated with both cardiovascular and non-cardiovascular mortality.MethodsIn a Dutch prospective nation-wide cohort study among incident patients on chronic dialysis, 1077 patients completed the Mental Health Inventory, both at 3 and 12months after starting dialysis. Cox regression models were used to calculate crude and adjusted hazard ratios (HRs) for mortality for patients with depressive symptoms at 3months only (baseline only), at 12months only (new-onset), and both at 3 and 12months (persistent), using patients without depressive symptoms at 3 and 12months as reference group.ResultsDepressive symptoms at baseline only seemed to be a strong marker for non-cardiovascular mortality (HRadj 1.91, 95% CI 1.26–2.90), whereas cardiovascular mortality was only moderately increased (HRadj 1.41, 95% CI 0.85–2.33). In contrast, new-onset depressive symptoms were moderately associated with both cardiovascular (HRadj 1.66, 95% CI 1.06–2.58) and non-cardiovascular mortality (HRadj 1.46, 95% CI 0.97–2.20). Among patients with persistent depressive symptoms, a poor survival was observed due to both cardiovascular (HRadj 2.14, 95% CI 1.42–3.24) and non-cardiovascular related mortality (HRadj 1.76, 95% CI 1.20–2.59).ConclusionThis study showed that different courses of depressive symptoms were associated with a poor survival after the start of dialysis. In particular, temporary depressive symptoms at the start of dialysis may be a strong marker for non-cardiovascular mortality, whereas persistent depressive symptoms were associated with both cardiovascular and non-cardiovascular mortality