Statistical complexity of reasons for encounter in high users of out of hours primary care:analysis of a national service

Background: Managing demand for urgent and unscheduled care is a major problem for health services globally. A particular issue is that some patients appear to make heavy use of services, including primary care out of hours. We hypothesised that greater variation (statistical complexity) in reasons for attending primary care out of hours services may be a useful marker of patients at high risk of ongoing heavy service use. Methods: We analysed an anonymised dataset of contacts with the primary care out of hours care for Scotland in 2011. This contained 120,395 contacts from 13,981 high-using patients who made 5 or more contacts during a calendar year. We allocated the stated reason for each encounter into one of 14 categories. For each patient we calculated measures of statistical complexity of reasons for encounter including the count of different categories, Herfindahl index and statistical entropy of either the categories themselves, or the category transitions. We examined the association of these measures of statistical complexity with patient and healthcare use characteristics. Results: The high users comprised 2.4% of adults using the service and accounted for 15% of all contacts. Statistical complexity (as entropy of categories) increased with number of contacts but was not substantially influenced by either patient age or sex. This lack of association with age was unexpected as with increasing multi-morbidity one would expect greater variability in reason for encounter. Between 5 and 10 consultations, higher entropy was associated with a reduced likelihood of further consultations. In contrast, the occurrence of one or more contacts for a mental health problem was associated with increased likelihood of further consultations. Conclusion: Complexity of reason for encounter can be estimated in an out of hours primary care setting. Similar levels of statistical complexity are seen in younger and older adults (suggesting that it is more to do with consultation behaviour than morbidity) but it is not a predictor of ongoing high use of urgent care.</p

Do healthcare services behave as complex systems? Analysis of patterns of attendance and implications for service delivery

Background: The science of complex systems has been proposed as a way of understanding health services and the demand for them, but there is little quantitative evidence to support this. We analysed patterns of healthcare use in different urgent care settings to see if they showed two characteristic statistical features of complex systems: heavy-tailed distributions (including the inverse power law) and generative burst patterns. Methods: We conducted three linked studies. In study 1 we analysed the distribution of number of contacts per patient with an urgent care service in two settings: emergency department (ED) and primary care out-of-hours (PCOOH) services. We hypothesised that these distributions should be heavy-tailed (inverse power law or log-normal) in keeping with typical complex systems. In study 2 we analysed the distribution of bursts of contact with urgent care services by individuals: correlated bursts of activity occur in complex systems and represent a mechanism by which overall heavy-tailed distributions arise. In study 3 we replicated the approach of study 1 using data systematically identified from published sources. Results: Study 1 involved data from a PCOOH service in Scotland (725,000) adults, 1.1 million contacts) and an ED in New Zealand (60,000 adults, 98,000 contacts). The total number of contacts per individual in each dataset was statistically indistinguishable from an inverse power law (p &gt; 0.05) above 4 contacts for the PCOOH data and 3 contacts for the ED data. Study 2 found the distribution of contact bursts closely followed a heavy-tailed distribution (p &lt; 0.008), indicating the presence of correlated bursts. Study 3 identified data from 17 studies across 8 countries and found distributions similar to study 1 in all of them. Conclusions: Urgent healthcare use displays characteristic statistical features of large complex systems. These studies provide strong quantitative evidence that healthcare services behave as complex systems and have important implications for urgent care. Interventions to manage demand must address drivers for consultation across the whole system: focusing on only the highest users (in the tail of the distribution) will have limited impact on efficiency. Bursts of attendance - and ways to shorten them - represent promising targets for managing demand.</p

A taxonomy of explanations in a general practitioner clinic for patients with persistent “medically unexplained” physical symptoms

MSS1 and MSS2 were supported by grants from the Chief Scientist Office of the Scottish Government (references CZG/2/412 and CZH/4/945). We are grateful to the general practitioners and patients who participated in these studies.Peer reviewedPostprin

Evaluation of matricellular proteins as potential therapeutics for the treatment of human chronic skin wounds

There is currently an unmet need for treatments to enhance healing of human chronic skin wounds. Previously, therapy development has focused on growth factors and physical matrices, often resulting in disappointing clinical outcomes. In this thesis, we approached chronic skin wound treatment with a focus on fibrosis and matricellular proteins. Fibrosis is a pathological condition where tissue repair continues, unchecked, resulting in excess contraction, matrix accumulation and fibrogenic growth factor activity; features critically reduced in chronic skin wounds. Identifying factors that promote fibrosis may offer new therapeutic targets for use in chronic skin wounds. Two such factors are the matricellular proteins periostin and CCN2. As a group, matricellular proteins have established roles in acute wound healing; facilitating growth factor signaling, matrix production and contraction. However, as of yet, matricellular proteins represent an uninvestigated resource for modulating chronic skin wound healing. The objective of this thesis was to determine the potential of periostin and CCN2 as therapeutics for accelerating skin wound healing. Periostin is up-regulated during skin healing but its function was unknown. Using periostin knockout mice, we observed a delay in fullthickness excisional wound closure in the absence of periostin. This delay was attributed to a lack of myofibroblast differentiation, central to wound contraction, both in vivo and in vitro. Next we examined the expression patterns of periostin and CCN2 in tissue samples from human chronic skin wounds. Within these wounds CCN2 was not induced and periostin was decreased. These expression patterns were likely due to the environment of the wounds since fibroblasts cultured from wound tissue expressed periostin and CCN2, responded to TGFβ, proliferated and contracted collagen gels; consistent with a fibrotic phenotype. Using a mouse model of impaired diabetic skin healing, we found that delivery of recombinant periostin or CCN2 accelerated wound healing. The mechanisms through which periostin and CCN2 delivery influenced wound healing were distinct, and combination of the two treatments produced synergistic outcomes. These findings represent the first report of using matricellular proteins to enhance healing of diabetic skin wounds in an animal model, with an aim to improve healing of human chronic skin wounds

DPSIR-Two decades of trying to develop a unifying framework for marine environmental management?

© 2016 Patrício, Elliott, Mazik, Papadopoulou and Smith. Determining and assessing the links between human pressures and state-changes in marine and coastal ecosystems remains a challenge. Although there are several conceptual frameworks for describing these links, the Drivers-Pressures-State change-Impact-Response (DPSIR) framework has been widely adopted. Two possible reasons for this are: either the framework fulfills a major role, resulting from convergent evolution, or the framework is used often merely because it is used often, albeit uncritically. This comprehensive review, with lessons learned after two decades of use, shows that the approach is needed and there has been a convergent evolution in approach for coastal and marine ecosystem management. There are now 25 derivative schemes and a widespread and increasing usage of the DPSIR-type conceptual framework as a means of structuring and analyzing information in management and decision-making across ecosystems. However, there is less use of DPSIR in fully marine ecosystems and even this was mainly restricted to European literature. Around half of the studies are explicitly conceptual, not illustrating a solid case study. Despite its popularity since the early 1990s among the scientific community and the recommendation of several international institutions (e.g., OECD, EU, EPA, EEA) for its application, the framework has notable weaknesses to be addressed. These primarily relate to the long standing variation in interpretation (mainly between natural and social scientists) of the different components (particularly P, S, and I) and to over-simplification of environmental problems such that cause-effect relationships cannot be adequately understood by treating the different DPSIR components as being mutually exclusive. More complex, nested, conceptual models and models with improved clarity are required to assess pressure-state change links in marine and coastal ecosystems. Our analysis shows that, because of its complexity, marine assessment and management constitutes

The cochlea as a smart structure

The cochlea is part of the inner ear and its mechanical response provides us with many aspects of our amazingly sensitive and selective hearing. The human cochlea is a coiled tube, with two main fluid chambers running along its length, separated by a 35 mm-long flexible partition that has its own internal dynamics. A dispersive wave can propagate along the cochlea due to the interaction between the inertia of the fluid and the dynamics of the partition. This partition includes about 12 000 outer hair cells, which have different structures, on a micrometre and a nanometre scale, and act both as motional sensors and as motional actuators. The local feedback action of all these cells amplifies the motion inside the inner ear by more than 40 dB at low sound pressure levels. The feedback loops become saturated at higher sound pressure levels, however, so that the feedback gain is reduced, leading to a compression of the dynamic range in the cochlear amplifier. This helps the sensory cells, with a dynamic range of only about 30 dB, to respond to sounds with a dynamic range of more than 120 dB. The active and nonlinear nature of the dynamics within the cochlea give rise to a number of other phenomena, such as otoacoustic emissions, which can be used as a diagnostic test for hearing problems in newborn children, for example. In this paper we view the mechanical action of the cochlea as a smart structure. In particular a simplified wave model of the cochlear dynamics is reviewed that represents its essential features. This can be used to predict the motion along the cochlea when the cochlea is passive, at high levels, and also the effect of the cochlear amplifier, at low level

Immersion microscopy based on photonic crystal materials

Theoretical model of the enhanced optical resolution of the surface plasmon immersion microscope is developed, which is based on the optics of surface plasmon Bloch waves in the tightly bound approximation. It is shown that a similar resolution enhancement may occur in a more general case of an immersion microscope based on photonic crystal materials with either positive or negative effective refractive index. Both signs of the effective refractive index have been observed in our experiments with surface plasmon immersion microscope, which is also shown to be capable of individual virus imaging.Comment: 23 pages, 10 figure