ABSTRACT
The COVID-19 pandemic has illustrated the unprecedented challenges of ensuring the continuity of operations in a supply chain as suppliers' and their suppliers stop producing due the spread of infection, leading to a degradation of downstream customer service levels in a ripple effect. In this paper, we contextualize a dynamic approach and propose an optimal control model for supply chain reconfiguration and ripple effect analysis integrated with an epidemic dynamics model. We provide supply chain managers with the optimal choice over a planning horizon among subsets of interchangeable suppliers and corresponding orders; this will maximize demand satisfaction given their prices, lead times, exposure to infection, and upstream suppliers' risk exposure. Numerical illustrations show that our prescriptive forward-looking model can help reconfigure a supply chain and mitigate the ripple effect due to reduced production because of suppliers' infected workers. A risk aversion factor incorporates a measure of supplier risk exposure at the upstream echelons. We examine three scenarios: (a) infection limits the capacity of suppliers, (b) the pandemic recedes but not at the same pace for all suppliers, and (c) infection waves affect the capacity of some suppliers, while others are in a recovery phase. We illustrate through a case study how our model can be immediately deployed in manufacturing or retail supply chains since the data are readily accessible from suppliers and health authorities. This work opens new avenues for prescriptive models in operations management and the study of viable supply chains by combining optimal control and epidemiological models.
ABSTRACT
BACKGROUND: Psoriatic arthritis (PsA) is an inflammatory arthritis associated with psoriasis in up to one third of psoriatic patients. Clinically it's characterized from an insidious onset. To help clinicians screen for PsA, several screening tools have been developed. The psoriatic arthritis screening and evaluation questionnaire (PASE) is one of the most used in the Psocare units. The sensibility of PASE is of 83% with a cut off of 47 or greater. The aim of our study is to create an Italian self-administered questionnaire, lighter than the PASE, able to identify patients who need a rheumatologic consultation. METHODS: Between April and June 2016 an Italian group of dermatologists and rheumatologists from north Italy developed a new questionnaire called Screening Tool for Rheumatologic Investigation in Psoriatic Patient (STRIPP). Two hundred and twelve patients with the diagnosis of psoriasis, were screened with STRIPP by dermatologists and all of them sent to the rheumatologist. RESULTS: Forty seven out of 212 patients received the diagnosis of early psoriatic arthritis. Statistical analysis (Spearman Rank correlation Test, Mann Whitney Test) showed a specificity of 93.3% and a sensibility of 91.5% taking a point of 3.5 as a cut-off. CONCLUSIONS: The STRIPP is a very easy questionnaire, quick to fill out and has a very high sensitivity and specificity, higher than the PASE. Our future goal will be to screen more patients for validating the STRIPP questionnaire.
