Combining Rasch and cluster analysis: a novel method for developing rheumatoid arthritis states for use in valuation studies

Purpose: Health states that describe an investigated condition are a crucial component of valuation studies. The health states need to be distinct, comprehensible, and data-driven. The objective of this study was to describe a novel application of Rasch and cluster analyses in the development of three rheumatoid arthritis health states. Methods: The Stanford Health Assessment Questionnaire (HAQ) was subjected to Rasch analysis to select the items that best represent disability. K-means cluster analysis produced health states with the levels of the selected items. The pain and discomfort domain from the EuroQol-5D was incorporated at the final stage. Results: The results demonstrate a methodology for reducing a dataset containing individual disease-specific scores to generate health states. The four selected HAQ items were bending down, climbing steps, lifting a cup to your mouth, and standing up from a chair. Conclusions: Overall, the combined use of Rasch and cluster analysis has proved to be an effective technique for identifying the most important items and levels for the construction of health states

A New Generating Function for Calculating the Igusa Local Zeta Function

A new method is devised for calculating the Igusa local zeta function $Z_f$ of a polynomial $f(x_1,\dots,x_n)$ over a $p$-adic field. This involves a new kind of generating function $G_f$ that is the projective limit of a family of generating functions, and contains more data than $Z_f$. This $G_f$ resides in an algebra whose structure is naturally compatible with operations on the underlying polynomials, facilitating calculation of local zeta functions. This new technique is used to expand significantly the set of quadratic polynomials whose local zeta functions have been calculated explicitly. Local zeta functions for arbitrary quadratic polynomials over $p$-adic fields with $p$ odd are presented, as well as for polynomials over unramified $2$-adic fields of the form $Q+L$ where $Q$ is a quadratic form and $L$ is a linear form where $Q$ and $L$ have disjoint variables. For a quadratic form over an arbitrary $p$-adic field with odd $p$, this new technique makes clear precisely which of the three candidate poles are actual poles.Comment: 54 page

A qualitative study exploring the general population's perception of rheumatoid arthritis after being informed about disease adaptation

Purpose: This study aimed to gain an understanding of what factors induce individuals to alter their opinions about a health condition after being informed about disease adaptation and being given time to reflect and deliberate on this information. Rheumatoid arthritis (RA) states are used as an illustration. Methods: Semi-structured interviews were conducted with 12 members of the general population. They completed two time trade-off exercises for three RA states and underwent an adaptation exercise (AE) which consisted of listening to recordings of patients discussing how they adapted to RA. Also included was a structured discussion to encourage the participant to reflect on how the patients have adapted. Participants were shown their own health state values, as well as patient values. Findings: After being informed about disease adaptation and reflecting on the information, participants were more likely to consider adaptation and alter their opinions of RA if they were able to empathise with the patients in the AE. This enabled individuals to feel that they could cope by reflecting on their experience of RA in family and friends, by drawing on others for support if they had RA, and by having a positive attitude towards life. Conclusions: The results demonstrate that there is a range of reasons for which people change their perceptions about RA; this requires further exploration

Combining Rasch and cluster analysis: a novel method for developing rheumatoid arthritis states for use in valuation studies

Purpose: Health states that describe an investigated condition are a crucial component of valuation studies. The health states need to be distinct, comprehensible, and data-driven. The objective of this study was to describe a novel application of Rasch and cluster analyses in the development of three rheumatoid arthritis health states. Methods: The Stanford Health Assessment Questionnaire (HAQ) was subjected to Rasch analysis to select the items that best represent disability. K-means cluster analysis produced health states with the levels of the selected items. The pain and discomfort domain from the EuroQol-5D was incorporated at the final stage. Results: The results demonstrate a methodology for reducing a dataset containing individual disease-specific scores to generate health states. The four selected HAQ items were bending down, climbing steps, lifting a cup to your mouth, and standing up from a chair. Conclusions: Overall, the combined use of Rasch and cluster analysis has proved to be an effective technique for identifying the most important items and levels for the construction of health states.health state; Rasch analysis; cluster analysis; quality of life; rheumatoid arthritis

A qualitative study exploring the general population’s perception of rheumatoid arthritis after being informed about disease adaptation

Purpose: This study aimed to gain an understanding of what factors induce individuals to alter their opinions about a health condition after being informed about disease adaptation and being given time to reflect and deliberate on this information. Rheumatoid arthritis (RA) states are used as an illustration. Methods: Semi-structured interviews were conducted with 12 members of the general population. They completed two time trade-off exercises for three RA states and underwent an adaptation exercise (AE) which consisted of listening to recordings of patients discussing how they adapted to RA. Also included was a structured discussion to encourage the participant to reflect on how the patients have adapted. Participants were shown their own health state values, as well as patient values. Findings: After being informed about disease adaptation and reflecting on the information, participants were more likely to consider adaptation and alter their opinions of RA if they were able to empathise with the patients in the AE. This enabled individuals to feel that they could cope by reflecting on their experience of RA in family and friends, by drawing on others for support if they had RA, and by having a positive attitude towards life. Conclusions: The results demonstrate that there is a range of reasons for which people change their perceptions about RA; this requires further exploration.health state valuation; qualitative research; quality of life; disease adaptation

A qualitative study exploring the general population's perception of rheumatoid arthritis after being informed about disease adaptation

Purpose: This study aimed to gain an understanding of what factors induce individuals to alter their opinions about a health condition after being informed about disease adaptation and being given time to reflect and deliberate on this information. Rheumatoid arthritis (RA) states are used as an illustration. Methods: Semi-structured interviews were conducted with 12 members of the general population. They completed two time trade-off exercises for three RA states and underwent an adaptation exercise (AE) which consisted of listening to recordings of patients discussing how they adapted to RA. Also included was a structured discussion to encourage the participant to reflect on how the patients have adapted. Participants were shown their own health state values, as well as patient values. Findings: After being informed about disease adaptation and reflecting on the information, participants were more likely to consider adaptation and alter their opinions of RA if they were able to empathise with the patients in the AE. This enabled individuals to feel that they could cope by reflecting on their experience of RA in family and friends, by drawing on others for support if they had RA, and by having a positive attitude towards life. Conclusions: The results demonstrate that there is a range of reasons for which people change their perceptions about RA; this requires further exploration

Improved V II log(gfgf) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Use of two spectrometers, independent radiometric calibration methods, and independent data analysis routines enables a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log {\epsilon}(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = -2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.Comment: 32 pages, 7 tables (3 machine-readable), 8 figures; accepted for publication in ApJ