Proof of Single-Replica Equivalence in Short-Range Spin Glasses

We consider short-range Ising spin glasses in equilibrium at infinite system size, and prove that, for fixed bond realization and a given Gibbs state drawn from a suitable metastate, each translation and locally invariant function (for example, self-overlaps) of a single pure state in the decomposition of the Gibbs state takes the same value for all the pure states in that Gibbs state. We describe several significant applications to spin glasses.

Complexity as information in spin-glass Gibbs states and metastates: Upper bounds at nonzero temperature and long-range models

In classical finite-range spin systems, especially those with disorder such as spin glasses, a low-temperature Gibbs state may be a mixture of a number of pure or ordered states; the complexity of the Gibbs state has been defined in the past roughly as the logarithm of this number, assuming the question is meaningful in a finite system. As nontrivial pure-state structure is lost in finite size, in a recent paper [Phys. Rev. E 101, 042114 (2020)2470-004510.1103/PhysRevE.101.042114] Höller and the author introduced a definition of the complexity of an infinite-size Gibbs state as the mutual information between the pure state and the spin configuration in a finite region, and applied this also within a metastate construction. (A metastate is a probability distribution on Gibbs states.) They found an upper bound on the complexity for models of Ising spins in which each spin interacts with only a finite number of others, in terms of the surface area of the region, for all T≥0. In the present paper, the complexity of a metastate is defined likewise in terms of the mutual information between the Gibbs state and the spin configuration. Upper bounds are found for each of these complexities for general finite-range (i.e., short- or long-range, in a sense we define) mixed p-spin interactions of discrete or continuous spins (such as m-vector models), but only for T>0. For short-range models, the bound reduces to the surface area. For long-range interactions, the definition of a Gibbs state has to be modified, and for these models we also prove that the states obtained within the metastate constructions are Gibbs states under the modified definition. All results are valid for a large class of disorder distributions.

Nontrivial maturation metastate-average state in a one-dimensional long-range Ising spin glass: Above and below the upper critical range

Understanding the low-temperature pure state structure of spin glasses remains an open problem in the field of statistical mechanics of disordered systems. Here we study Monte Carlo dynamics, performing simulations of the growth of correlations following a quench from infinite temperature to a temperature well below the spin-glass transition temperature T_{c} for a one-dimensional Ising spin-glass model with diluted long-range interactions. In this model, the probability P_{ij} that an edge {i,j} has nonvanishing interaction falls as a power law with chord distance, P_{ij}∝1/R_{ij}^{2σ}, and we study a range of values of σ with 1/2<σ<1. We consider a correlation function C_{4}(r,t). A dynamic correlation length that shows power-law growth with time ξ(t)∝t^{1/z} can be identified in the data and, for large time t, C_{4}(r,t) decays as a power law r^{-α_{d}} with distance r when r≪ξ(t). The calculation can be interpreted in terms of the maturation metastate averaged Gibbs state, or MMAS, and the decay exponent α_{d} differentiates between a trivial MMAS (α_{d}=0), as expected in the droplet picture of spin glasses, and a nontrivial MMAS (α_{d}≠0), as in the replica-symmetry-breaking (RSB) or chaotic pairs pictures. We find nonzero α_{d} even in the regime σ>2/3 which corresponds to short-range systems below six dimensions. For σ<2/3, the decay exponent α_{d} follows the RSB prediction for the decay exponent α_{s}=3-4σ of the static metastate, consistent with a conjectured statics-dynamics relation, while it approaches α_{d}=1-σ in the regime 2/3<σ<1; however, it deviates from both lines in the vicinity of σ=2/3.

Delay in diagnosis of patients with head-and-neck cancer in Canada: impact of patient and provider delay

Background

Head-and-neck cancers (hncs) often present at an advanced stage, leading to poor outcomes. Late presentation might be attributable to patient delays (reluctance to seek treatment, for instance) or provider delays (misdiagnosis, prolonged wait time for consultation, for example). The objective of the present study was to examine the length and cause of such delays in a Canadian universal health care setting.

Methods

Patients presenting for the first time to the hnc multidisciplinary team (mdt) with a biopsy-proven hnc were recruited to this study. Patients completed a survey querying initial symptom presentation, their previous medical appointments, and length of time between appointments. Clinical and demographic data were collected for all patients.

Results

The average time for patients to have their first appointment at the mdt clinic was 15.1 months, consisting of 3.9 months for patients to see a health care provider (hcp) for the first time since symptom onset and 10.7 months from first hcp appointment to the mdt clinic. Patients saw an average of 3 hcps before the mdt clinic visit (range: 1-7). No significant differences in time to presentation were found based on stage at presentation or anatomic site.

Conclusions

At our tertiary care cancer centre, a patient's clinical pathway to being seen at the mdt clinic shows significant delays, particularly in the time from the first hcp visit to mdt referral. Possible methods to mitigate delay include education about hnc for patients and providers alike, and a more streamlined referral system.

One-step replica-symmetry-breaking phase below the de Almeida-Thouless line in low-dimensional spin glasses

The de Almeida-Thouless (AT) line is the phase boundary in the temperature-magnetic field plane of an Ising spin glass at which a continuous (i.e., second-order) transition from a paramagnet to a replica-symmetry-breaking (RSB) phase occurs, according to mean-field theory. Here, using field-theoretic perturbative renormalization group methods on the Bray-Roberts reduced Landau-Ginzburg-type theory for a short-range Ising spin glass in space of dimension d, we show that at nonzero magnetic field the nature of the corresponding transition is modified as follows: (a) For d-6 small and positive, with increasing field on the AT line, first, the ordered phase just below the transition becomes the so-called one-step RSB, instead of the full RSB that occurs in mean-field theory; the transition on the AT line remains continuous with a diverging correlation length. Then at a higher field, a tricritical point separates the latter transition from a quasi-first-order one, that is one at which the correlation length does not diverge, and there is a jump in part of the order parameter, but no latent heat. The location of the tricritical point tends to zero as d→6^{+}. (b) For d≤6, we argue that the quasi-first-order transition could persist down to arbitrarily small nonzero fields, with a transition to full RSB still expected at lower temperature. Whenever the quasi-first-order transition occurs, it is at a higher temperature than the AT transition would be for the same field, preempting it as the temperature is lowered. These results may explain the reported absence of a diverging correlation length in the presence of a magnetic field in low-dimensional spin glasses in some simulations and in high-temperature series expansions. We also draw attention to the similarity of the "dynamically frozen" state, which occurs at temperatures just above the quasi-first-order transition, and the "metastate-average state" of the one-step RSB phase, and discuss the issue of the number of pure states in either.

Multicritical Point on the de Almeida-Thouless Line in Spin Glasses in d>6 Dimensions

The de Almeida-Thouless (AT) line in Ising spin glasses is the phase boundary in the temperature T and magnetic field h plane below which replica symmetry is broken. Using perturbative renormalization group (RG) methods, we show that, when the dimension d of space is just above six, there is a multicritical point (MCP) on the AT line, which separates a low-field regime, in which the critical exponents have mean-field values, from a high-field regime, where the RG flows run away to infinite coupling strength; as d approaches six from above, the MCP approaches the zero-field critical point exponentially in 1/(d-6). Thus, on the AT line, perturbation theory for the critical properties breaks down at a sufficiently large magnetic field even above 6 dimensions, as well as for all nonzero fields when d≤6, as was known previously. We calculate the exponents at the MCP to first order in ϵ=d-6>0. The fate of the MCP as d increases from just above six to infinity is not known.

Triviality of the ground-state metastate in long-range Ising spin glasses in one dimension

We consider the one-dimensional model of a spin glass with independent Gaussian-distributed random interactions, which have mean zero and variance 1/|i-j|^{2σ}, between the spins at sites i and j for all i≠j. It is known that, for σ>1, there is no phase transition at any nonzero temperature in this model. We prove rigorously that, for σ>3/2, any translation-covariant Newman-Stein metastate for the ground states (i.e., the frequencies with which distinct ground states are observed in finite-size samples in the limit of infinite size, for given disorder) is trivial and unique. In other words, for given disorder and asymptotically at large sizes, the same ground state, or its global spin flip, is obtained (almost) always. The proof consists of two parts: One is a theorem (based on one by Newman and Stein for short-range two-dimensional models), valid for all σ>1, that establishes triviality under a convergence hypothesis on something similar to the energies of domain walls and the other (based on older results for the one-dimensional model) establishes that the hypothesis is true for σ>3/2. In addition, we derive heuristic scaling arguments and rigorous exponent inequalities which tend to support the validity of the hypothesis under broader conditions. The constructions of various metastates are extended to all values σ>1/2. Triviality of the metastate in bond-diluted power-law models for σ>1 is proved directly.

Paediatric hereditary angioedema: a survey of UK service provision and patient experience

Hereditary angioedema (HAE) is a rare disease characterized by episodes of potentially life-threatening angioedema. For affected children in the United Kingdom, there are relatively few data regarding disease prevalence, service organization and the humanistic burden of the disease. To improve knowledge in these areas, we surveyed major providers of care for children with HAE. A questionnaire was sent to major paediatric centres to determine patient numbers, symptoms, diagnostic difficulties, management and available services. In addition, all patients at a single centre were given a questionnaire to determine the experiences of children and their families. Sixteen of 28 centres responded, caring for a total of 111 UK children. Seven children had experienced life-threatening crises. One-third of patients were on long-term prophylactic medication, including C1 inhibitor prophylaxis in four children. Eight centres reported patients who were initially misdiagnosed. Broad differences in management were noted, particularly regarding indications for long-term prophylaxis and treatment monitoring. We also noted substantial variation in the organization of services between centres, including the number of consultants contributing to patient care, the availability of specialist nurses, the availability of home therapy training and the provision of patient information. Ten of 12 patient/carer questionnaires were returned, identifying three common themes: the need to access specialist knowledge, the importance of home therapy and concerns around the direct effect of angioedema on their life. To our knowledge, this study represents the first dedicated survey of paediatric HAE services in the United Kingdom and provides useful information to inform the optimization of services.

Short-range Ising spin glasses: the metastate interpretation of replica symmetry breaking

Parisi's formal replica-symmetry-breaking (RSB) scheme for mean-field spin glasses has long been interpreted in terms of many pure states organized ultrametrically. However, the early version of this interpretation, as applied to the short-range Edwards-Anderson model, runs into problems because as shown by Newman and Stein (NS) it does not allow for chaotic size dependence, and predicts non-self-averaging that cannot occur. NS proposed the concept of the metastate (a probability distribution over infinite-size Gibbs states in a given sample that captures the effects of chaotic size dependence) and a nonstandard interpretation of the RSB results in which the metastate is nontrivial and is responsible for what was called non-self-averaging. In this picture, each state drawn from the metastate has the ultrametric properties of the old theory, but when the state is averaged using the metastate, the resulting mixed state has little structure. This picture was constructed so as to agree both with the earlier RSB results and with rigorous results. Here we use the effective field theory of RSB, in conjunction with the rigorous definitions of pure states and the metastate in infinite-size systems, to show that the nonstandard picture follows directly from the RSB mean-field theory. In addition, the metastate-averaged state possesses power-law correlations throughout the low-temperature phase; the corresponding exponent ζ takes the value 4 according to the field theory in high dimensions d, and describes the effective fractal dimension of clusters of spins. Further, the logarithm of the number of pure states in the decomposition of the metastate-averaged state that can be distinguished if only correlations in a window of size W can be observed is of order W(d-ζ). These results extend the nonstandard picture quantitatively; we show that arguments against this scenario are inconclusive. More generally, in terms of Parisi's function q(x), if q(0)≠∫(0)(1)dxq(x), then the metastate is nontrivial. In an Appendix, we also prove rigorously that the metastate-averaged state of the Sherrington-Kirkpatrick model is a uniform distribution on all spin configurations at all temperatures.

The epidemic of human papillomavirus and oropharyngeal cancer in a Canadian population

BACKGROUND

Sexually transmitted infection with the human papillomavirus (hpv) is responsible for a significant burden of human cancers involving the cervix, anogenital tract, and oropharynx. Studies in the United States and Europe have demonstrated an alarming increase in the frequency of hpv-positive oropharyngeal cancer, but the same direct evidence does not exist in Canada.

METHODS

Using the London Health Sciences Centre pathology database, we identified tonsillar cancers diagnosed between 1993 and 2011. Real-time polymerase chain reaction was then used on pre-treatment primary-site biopsy samples to test for dna from the high-risk hpv types 16 and 18. The study cohort was divided into three time periods: 1993-1999, 2000-2005, and 2006-2011.

RESULTS

Of 160 tumour samples identified, 91 (57%) were positive for hpv 16. The total number of tonsillar cancers significantly increased from 1993-1999 to 2006-2011 (32 vs. 68), and the proportion of cases that were hpv-positive substantially increased (25% vs. 62%, p < 0.002). Those changes were associated with a marked improvement in 5-year overall survival (39% in 1993-1999 vs. 84% in 2006-2011, p < 0.001). When all factors were included in a multivariable model, only hpv status predicted treatment outcome.

INTERPRETATION

The present study is the first to provide direct evidence that hpv-related oropharyngeal cancer is increasing in incidence in a Canadian population. Given the long lag time between hpv infection and clinically apparent malignancy, oropharyngeal cancer will be a significant clinical problem for the foreseeable future despite vaccination efforts.

Entanglement spectra of complex paired superfluids

We study the entanglement in various fully gapped complex paired states of fermions in two dimensions, focusing on the entanglement spectrum (ES), and using the Bardeen-Cooper-Schrieffer (BCS) form of the ground-state wave function on a cylinder. Certain forms of the pairing functions allow a simple and explicit exact solution for the ES. In the weak-pairing phase of ℓ-wave paired spinless fermions (ℓ odd), the universal low-lying part of the ES consists of |ℓ| chiral Majorana fermion modes [or 2|ℓ| (ℓ even) for spin-singlet states]. For |ℓ|>1, the pseudoenergies of the modes are split in general, but for all ℓ there is a zero-pseudoenergy mode at a zero wave vector if the number of modes is odd. This ES agrees with the perturbed conformal field theory of the edge excitations. For more general BCS states, we show how the entanglement gap diverges as a model pairing function is approached.

Theory of minimum spanning trees. I. Mean-field theory and strongly disordered spin-glass model

The minimum spanning tree (MST) is a combinatorial optimization problem: given a connected graph with a real weight ("cost") on each edge, find the spanning tree that minimizes the sum of the total cost of the occupied edges. We consider the random MST, in which the edge costs are (quenched) independent random variables. There is a strongly disordered spin-glass model due to Newman and Stein [Phys. Rev. Lett. 72, 2286 (1994)], which maps precisely onto the random MST. We study scaling properties of random MSTs using a relation between Kruskal's greedy algorithm for finding the MST, and bond percolation. We solve the random MST problem on the Bethe lattice (BL) with appropriate wired boundary conditions and calculate the fractal dimension D=6 of the connected components. Viewed as a mean-field theory, the result implies that on a lattice in Euclidean space of dimension d , there are of order W(d-D) large connected components of the random MST inside a window of size W , and that d=d(c)=D=6 is a critical dimension. This differs from the value 8 suggested by Newman and Stein. We also critique the original argument for 8, and provide an improved scaling argument that again yields d(c)=6 . The result implies that the strongly disordered spin-glass model has many ground states for d>6 , and only of order one below six. The results for MSTs also apply on the Poisson-weighted infinite tree, which is a mean-field approach to the continuum model of MSTs in Euclidean space, and is a limit of the BL. In a companion paper we develop an epsilon=6-d expansion for the random MST on critical percolation clusters.

Theory of minimum spanning trees. II. Exact graphical methods and perturbation expansion at the percolation threshold

Continuing the program begun by the authors in a previous paper, we develop an exact low-density expansion for the random minimum spanning tree (MST) on a finite graph and use it to develop a continuum perturbation expansion for the MST on critical percolation clusters in space dimension d . The perturbation expansion is proved to be renormalizable in d=6 dimensions. We consider the fractal dimension D(p) of paths on the latter MST; our previous results lead us to predict that D(p)=2 for d>d(c)=6 . Using a renormalization-group approach, we confirm the result for d>6 and calculate D(p) to first order in epsilon=6-d for d<6 using the connection with critical percolation, with the result D(p)=2-epsilon/7+O(epsilon(2)) .

Incompressible liquid state of rapidly rotating bosons at filling factor 3/2

Bosons in the lowest Landau level, such as rapidly rotating cold trapped atoms, are investigated numerically in the specially interesting case in which the filling factor (ratio of particle number to vortex number) is 3/2. When a moderate amount of a longer-range (e.g., dipolar) interaction is included, we find clear evidence that the ground state is in a phase constructed earlier by two of us, in which excitations possess non-Abelian statistics.

Minimum spanning trees and random resistor networks in d dimensions

We consider minimum-cost spanning trees, both in lattice and Euclidean models, in d dimensions. For the cost of the optimum tree in a box of size L , we show that there is a correction of order L(theta) , where theta< or =0 is a universal d -dependent exponent. There is a similar form for the change in optimum cost under a change in boundary condition. At nonzero temperature T , there is a crossover length xi approximately T(-nu) , such that on length scales larger than xi, the behavior becomes that of uniform spanning trees. There is a scaling relation theta=-1/nu, and we provide several arguments that show that nu and -1/theta both equal nu(perc) , the correlation length exponent for ordinary percolation in the same dimension d , in all dimensions d> or =1 . The arguments all rely on the close relation of Kruskal's greedy algorithm for the minimum spanning tree, percolation, and (for some arguments) random resistor networks. The scaling of the entropy and free energy at small nonzero T , and hence of the number of near-optimal solutions, is also discussed. We suggest that the Steiner tree problem is in the same universality class as the minimum spanning tree in all dimensions, as is the traveling salesman problem in two dimensions. Hence all will have the same value of theta=-3/4 in two dimensions.

[Analysis of the Ca2+ response of mycelial fungi to external effects by the recombinant aequorin method]

Using the mutant strain Aspergillus awamori 66A producing a recombinant Ca2+-dependent photosensitive protein aequorin, the dynamics of Ca2+ was studied for the first time in the cytosol of the micromycetes exposed to stressful factors, such as an increase in extracellular Ca2+ to 50 mM, hypoosmotic shock, and mechanical shock. Cell response to stress proved to involve an increase in the Ca2+ concentration in the cytosol, which was determined from the amplitude of aequorin luminescence and the time of the amplitude enhancement and relaxation. The level of Ca2+ response depended on the physiological stimulus. Inhibitory analysis with various agents that block Ca2+ channels and with agonists that specifically enhance the activity of the channels suggested that (1) the level of Ca2+ in the cytosol of micromycetes increases in response to stress because of the ion influx from both the growth medium and intracellular reservoirs and (2) the potential-dependent transport systems play the major role in the Ca2+ influx into the cytosol of the micromycete cells.

Exponents and bounds for uniform spanning trees in d dimensions

Uniform spanning trees are a statistical model obtained by taking the set of all spanning trees on a given graph (such as a portion of a cubic lattice in d dimensions), with equal probability for each distinct tree. Some properties of such trees can be obtained in terms of the Laplacian matrix on the graph, by using Grassmann integrals. We use this to obtain exact exponents that bound those for the power-law decay of the probability that k distinct branches of the tree pass close to each of two distinct points, as the size of the lattice tends to infinity.

Traveling salesman problem, conformal invariance, and dense polymers

We propose that the statistics of the optimal tour in the planar random Euclidean traveling salesman problem is conformally invariant on large scales. This is exhibited in the power-law behavior of the probabilities for the tour to zigzag repeatedly between two regions, and in subleading corrections to the length of the tour. The universality class should be the same as for dense polymers and minimal spanning trees. The conjectures for the length of the tour on a cylinder are tested numerically.

Cluster analysis of symptoms and health seeking behaviour differentiates subgroups of patients with severe irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a heterogeneous condition which is diagnosed according to specific bowel symptom clusters. The aim of the present study was to identify subgroups of IBS subjects using measures of rectal sensitivity and psychological symptoms, in addition to bowel symptoms. Such groupings, which cross conventional diagnostic approaches, may provide greater understanding of the pathogenesis of the condition and its treatment.

METHOD

A K means cluster analysis was used to group 107 clinic patients with IBS according to physiological, physical, and psychological parameters. All patients had severe IBS and had failed to respond to usual medical treatment. Twenty nine patients had diarrhoea predominant IBS, 26 constipation predominant, and 52 had an alternating bowel habit.

RESULTS

The clusters were most clearly delineated by two variables: "rectal perceptual threshold (volume)" and "number of doctor visits". Three subgroups were formed. Group I comprised patients with low distension thresholds and high rates of psychiatric morbidity, doctor consultations, interpersonal problems, and sexual abuse. Group II also had low distension thresholds but low rates of childhood abuse and moderate levels of psychiatric disorders. Group III had high distension thresholds, constipation or alternating IBS, and low rates of medical consultations and sexual abuse.

CONCLUSION

The marked differences across the three groups suggest that each may have a different pathogenesis and respond to different treatment approaches. Inclusion of psychosocial factors in the analysis enabled more clinically meaningful groups to be identified than those traditionally determined by bowel symptoms alone or rectal threshold.

Radiation-induced magnetoresistance oscillations in a 2D electron gas

Recent measurements of a 2D electron gas subjected to microwave radiation reveal a magnetoresistance with an oscillatory dependence on the ratio of radiation frequency to cyclotron frequency. We perform a diagrammatic calculation and find radiation-induced resistivity oscillations with the correct period and phase. Results are explained via a simple picture of current induced by photoexcited disorder-scattered electrons. The oscillations increase with radiation intensity, easily exceeding the dark resistivity and resulting in negative-resistivity minima. At high intensity, we identify additional features, likely due to multiphoton processes, which have yet to be observed experimentally.

Dense loops, supersymmetry, and Goldstone phases in two dimensions

Loop models in two dimensions can be related to O(N) models. The low-temperature dense-loops phase of such a model, or of its reformulation using a supergroup as symmetry, can have a Goldstone broken-symmetry phase for N<2. We argue that this phase is generic for -2<N<2 when crossings of loops are allowed, and distinct from the model of noncrossing dense loops first studied by Nienhuis [Phys. Rev. Lett. 49, 1062 (1982)]]. Our arguments are supported by our numerical results, and by a lattice model solved exactly by Martins et al. [Phys. Rev. Lett. 81, 504 (1998)]].

Prophylaxis of radiation-associated mucositis in conventionally treated patients with head and neck cancer: a double-blind, phase III, randomized, controlled trial evaluating the clinical efficacy of an antimicrobial lozenge using a validated mucositis scoring system

PURPOSE

Mucositis occurs in almost all patients treated with radiotherapy for head and neck cancer. The aim of this multicenter, double-blind, prospective, randomized trial was to evaluate the clinical efficacy of an economically viable antimicrobial lozenge (bacitracin, clotrimazole, and gentamicin [BcoG]) in the alleviation of radiation-induced mucositis in patients with head and neck cancer.

PATIENTS AND METHODS

One hundred thirty-seven eligible patients were randomized to treatment with either antimicrobial lozenge (69 patients) or placebo lozenge (68 patients). The primary end point of the study was the time to development of severe mucositis from the start of radiotherapy. Secondary end points included severity and duration of mucositis, pain measurement, radiation therapy interruption, and quality of life. Mucositis was scored using a validated mucositis scoring system.

RESULTS

Toxicity profiles were similar between the two arms of the study. The median time to development of severe mucositis from the start of radiotherapy was 3.61 weeks on BCoG and 3.96 weeks on placebo (P =.61). There were no statistically significant differences between the arms in the extent of severe mucositis as measured by physician, in oral toxicities as recorded by patients, or in radiotherapy delays.

CONCLUSION

This study was conducted on the basis of a pilot study that demonstrated the BCoG lozenge to be tolerable and microbiologically efficacious. A validated mucositis scoring system was used. However, in this group of patients treated with conventional radiotherapy, the lozenge did not impact significantly on the severity of mucositis. Whether such a lozenge would be beneficial in treatment situations where rate of severe mucositis is higher (ie, in patients treated with unconventional fractionation or with concomitant chemotherapy) is unknown.

Quantum hall states and boson triplet condensate for rotating spin-1 bosons

We propose and analyze two series of clustered quantum Hall states for rotating systems of spin-1 bosons. The first series [labeled SU(4)(k)] includes the exact ground states of a model Hamiltonian at large angular momentum L, and also for N=3k particles at L=N. The latter is a spin-singlet boson-triplet condensate. The second series, labeled SO(5)(k), includes exact ground states at large L for different parameter values.

Health-related quality of life and health care costs in severe, refractory irritable bowel syndrome

BACKGROUND

The irritable bowel syndrome (IBS) may lead to considerable impairment of health-related quality of life and high health care costs. It is not clear whether these poor outcomes directly result from severe bowel symptoms or reflect a coexisting psychiatric disorder.

OBJECTIVE

To determine whether bowel symptom severity and psychological symptoms directly influence health-related quality of life and health care costs.

DESIGN

Cross-sectional survey.

SETTING

Secondary and tertiary gastroenterology clinics.

PATIENTS

257 patients with severe IBS who did not respond to usual treatments and were recruited for a trial of psychological treatment.

MEASUREMENTS

Predictors were abdominal pain, entries in a diary of 10 IBS symptoms, and measures of psychological symptoms. Outcomes were inability to work, health-related quality of life (measured by Medical Outcomes Survey 36-item short-form questionnaire [SF-36] physical component summary scores), and health care and productivity costs. Predictor and outcome measures were compared by using multiple regression and logistic regression analyses.

RESULTS

Abdominal pain occurred on average 24 days per month and activities were restricted on 145 days of the previous 12 months. The mean (+/-SD) Hamilton depression score was 11.3 +/- 6.1. The SF-36 physical component summary score was low (37.7 +/- 10.6), and the patients had incurred high health care costs ($1743 +/- $2263) over the previous year. Global severity and somatization scores on the Symptom Checklist 90 Revised, abdominal pain, and Hamilton depression scores independently contributed to the physical component score of the SF-36 (adjusted R(2) = 35.2%), but only psychological scores were associated with disability due to ill health. These variables did not accurately predict health care or other costs (adjusted R(2) = 9.3%). History of sexual abuse was not an independent predictor of outcome.

CONCLUSIONS

Both abdominal and psychological symptoms are independently associated with impaired health-related quality of life in patients with severe IBS. Optimal treatment is likely to require a holistic approach. Since health care and loss of productivity costs are not clearly associated with these symptoms, alleviation of them will not necessarily lead to reduced costs.

Gastric emptying and intestinal transit of pancreatic enzyme supplements in cystic fibrosis

OBJECTIVE

To investigate gastric emptying and intestinal transit of pelleted pancreatin in relation to food boluses.

METHODS

Dual isotope scintigraphy combined with breath hydrogen sampling was used to track the concurrent gastric emptying and intestinal transit of 111indium labelled microspheres and a 99mtechnetium labelled tin colloid test meal. Twelve pancreatic insufficient cystic fibrosis patients aged 5 to 38 years performed the study.

RESULTS

50% gastric emptying times showed patient to patient variation. The mean discrepancy in 50% gastric emptying times between the two labels was > 67 minutes. Mean small bowel transit time for the food bolus was prolonged at 3.6 minutes. A significant correlation was seen between weight standard deviation score and 50% emptying time for pancreatin (r = +0.73).

CONCLUSION

Gastric mixing of food and pancreatin may be limited by rapid emptying of microspheres. Patients with high dosage requirements could benefit from changing the pattern of their pancreatin supplementation.

Innovative service redesign and resource reallocation: responding to political realities, mental health reform and community mental health needs

General hospital mental health programs in large inner city communities face challenges in developing responsive services for populations facing high rates of serious mental illness, substance abuse, homelessness, and poverty. In addition provincial political pressures such as Mental Health Reform and hospital restructuring have caused general hospital mental health programs to reevaluate how services are delivered and resources are allocated. This paper describes how one inner city mental health service in a university teaching setting developed successful strategies to respond to these pressures. Strategies included: (a) merging two general hospital mental health services to pool resources; (b) allocating resources to innovative care delivery models consistent with provincial reforms and community needs; (c) fostering staff role changes, job transitions, and the development of new professional competencies to complement the innovative care delivery models; and (d) developing processes to evaluate the effects of these changes on client.