Etiologic predictive value of a rapid immunoassay for detection of group A streptococcus antigen from throat swabs in patients presenting with a sore throat

Context: A sore throat is a common symptom mainly caused by virus but also by a variety of bacteria such as group A betahaemolytic streptococci (GAS) often resulting in unnecessary antibiotic prescribing. Combinations of symptoms and scores are not specific enough to accurately sort out aetiology. Rapid diagnostic antigen tests (RADT) have demonstrated high sensitivity and specificity in detecting presence of GAS. Objective: Establish the probability that finding of GAS in a RADT shows a true link between symptoms and GAS while considering carriers of GAS ill from a virus. Design: Cross-sectional study comparing two groups. Setting: Emergency department (ED) also managing primary health care cases in a remote rural town with 22,000 residents. Patients/Participants: 101 consecutive children aged 3-15 years attending for a sore throat as the main complaint and 147 consecutive children of the same age attending the same ED for other reasons than an infection. Main And Secondary Outcome Measures: Positive and negative Etiologic Predictive Value (EPV). Results: Positive EPV was 98% (88-100%). Negative EPV was 98% (97-99%). The positive EPV depends on setting and findings in this study and may not be transferable to other settings. It was mathematically shown that negative EPV found in this study is valid in all other reasonable settings and hence can be transferred to any other setting. Conclusions: The evaluated RADT (Alere Test Pack+Plus With OBC Strep A) is always useful to rule out GAS infection in patients with an uncomplicated sore throat. It is often, depending on setting, useful to rule in a GAS infection in these patients

Computing Shortest Paths for Any Number of Hops

In this paper, we introduce and investigate a “new” path optimization problem that we denote the all hops optimal path (AHOP) problem. The problem involves identifying, for all hop counts, the optimal, i.e., minimum weight, path(s) between a given source and destination(s). The AHOP problem arises naturally in the context of quality-of-service (QoS) routing in networks, where routes (paths) need to be computed that provide services guarantees, e.g., delay or bandwidth, at the minimum possible “cost” (amount of resources required) to the network. Because service guarantees are typically provided through some form of resource allocation on the path (links) computed for a new request, the hop count, which captures the number of links over which resources are allocated, is a commonly used cost measure. As a result, a standard approach for determining the cheapest path available that meets a desired level of service guarantees is to compute a minimum hop shortest (optimal) path. Furthermore, for efficiency purposes, it is desirable to precompute such optimal minimum hop paths for all possible service requests. Providing this information gives rise to solving the AHOP problem. The paper’s contributions are to investigate the computational complexity of solving the AHOP problem for two of the most prevalent cost functions (path weights) in networks, namely, additive and bottleneck weights. In particular, we establish that a solution based on the Bellman–Ford algorithm is optimal for additive weights, but show that this does not hold for bottleneck weights for which a lower complexity solution exists

Etiologic predictive value of a rapid immunoassay for detection of group A streptococcus antigen from throat swabs in patients presenting with a sore throat

Context: A sore throat is a common symptom mainly caused by virus but also by a variety of bacteria such as group A betahaemolytic streptococci (GAS) often resulting in unnecessary antibiotic prescribing. Combinations of symptoms and scores are not specific enough to accurately sort out aetiology. Rapid diagnostic antigen tests (RADT) have demonstrated high sensitivity and specificity in detecting presence of GAS. Objective: Establish the probability that finding of GAS in a RADT shows a true link between symptoms and GAS while considering carriers of GAS ill from a virus. Design: Cross-sectional study comparing two groups. Setting: Emergency department (ED) also managing primary health care cases in a remote rural town with 22,000 residents. Patients/Participants: 101 consecutive children aged 3-15 years attending for a sore throat as the main complaint and 147 consecutive children of the same age attending the same ED for other reasons than an infection. Main And Secondary Outcome Measures: Positive and negative Etiologic Predictive Value (EPV). Results: Positive EPV was 98% (88-100%). Negative EPV was 98% (97-99%). The positive EPV depends on setting and findings in this study and may not be transferable to other settings. It was mathematically shown that negative EPV found in this study is valid in all other reasonable settings and hence can be transferred to any other setting. Conclusions: The evaluated RADT (Alere Test Pack+Plus With OBC Strep A) is always useful to rule out GAS infection in patients with an uncomplicated sore throat. It is often, depending on setting, useful to rule in a GAS infection in these patients

Distance Oracles for Time-Dependent Networks

We present the first approximate distance oracle for sparse directed networks with time-dependent arc-travel-times determined by continuous, piecewise linear, positive functions possessing the FIFO property. Our approach precomputes $(1+\epsilon)-$approximate distance summaries from selected landmark vertices to all other vertices in the network. Our oracle uses subquadratic space and time preprocessing, and provides two sublinear-time query algorithms that deliver constant and $(1+\sigma)-$approximate shortest-travel-times, respectively, for arbitrary origin-destination pairs in the network, for any constant $\sigma > \epsilon$. Our oracle is based only on the sparsity of the network, along with two quite natural assumptions about travel-time functions which allow the smooth transition towards asymmetric and time-dependent distance metrics.Comment: A preliminary version appeared as Technical Report ECOMPASS-TR-025 of EU funded research project eCOMPASS (http://www.ecompass-project.eu/). An extended abstract also appeared in the 41st International Colloquium on Automata, Languages, and Programming (ICALP 2014, track-A