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M Herdman

Publications and source records attributed to M Herdman.

36 records · Page 2Linked to original sources
PubMed1999

Determining correspondence between scores on the EQ-5D "thermometer" and a 5-point categorical rating scale.

BACKGROUND: "Feeling thermometers" and category rating scales (CRS) can be used to measure self-rated health, though the interpretation of scores on the feeling thermometer may be problematic. OBJECTIVES: To analyze correspondence between scores of self-rated health on the EuroQol-5D "feeling thermometer" and a five-Point CRS. To determine the influence of sociodemographic variables on correspondence. RESEARCH DESIGN: Correspondence between EQ-5D "thermometer" scores and CRS categories was determined in a within-subjects design using data from a large-scale health survey. SUBJECTS: Twelve thousand, two hundred and forty-five members of the Spanish general population interviewed in the Catalan Health Interview Survey. MEASURES: Instruments used were the EQ-5D "feeling thermometer" and a five-Point CRS with categories from "excellent" to "poor." RESULTS: Median scores on the thermometer corresponding to CRS categories were as follows: poor = 40; fair = 53; good = 76; and very good = 80; excellent = 90; differences were statistically significant (P < 0.05). Ranges in thermometer scores covered by CRS categories varied from 23.5 points for the category "poor" to 13 points for the category "very good" (range, 25-75 percentiles), with considerable overlap between categories at the upper end of the scale. Median thermometer scores corresponding to the categories "good,""fair," and "poor" were lower in older respondents and in those with a lower educational level. CONCLUSIONS: Determining correspondence between CRS and thermometer scores is useful in interpreting and categorizing thermometer scores. The age and level of education in particular affect the interpretation of CRS categories, and should be taken into account when analyzing results obtained with such instruments.

Adolescent↗
PubMed1999

In situ identification of cyanobacteria with horseradish peroxidase-labeled, rRNA-targeted oligonucleotide probes.

Individual cyanobacterial cells are normally identified in environmental samples only on the basis of their pigmentation and morphology. However, these criteria are often insufficient for the differentiation of species. Here, a whole-cell hybridization technique is presented that uses horseradish peroxidase (HRP)-labeled, rRNA-targeted oligonucleotides for in situ identification of cyanobacteria. This indirect method, in which the probe-conferred enzyme has to be visualized in an additional step, was necessary since fluorescently monolabeled oligonucleotides were insufficient to overstain the autofluorescence of the target cells. Initially, a nonfluorescent detection assay was developed and successfully applied to cyanobacterial mats. Later, it was demonstrated that tyramide signal amplification (TSA) resulted in fluorescent signals far above the level of autofluorescence. Furthermore, TSA-based detection of HRP was more sensitive than that based on nonfluorescent substrates. Critical points of the assay, such as cell fixation and permeabilization, specificity, and sensitivity, were systematically investigated by using four oligonucleotides newly designed to target groups of cyanobacteria.

Bacterial Typing Techniques↗
PubMed1999

[The Spanish version of EuroQol: a description and its applications. European Quality of Life scale].

BACKGROUND: To introduce the EuroQol 5D (EQ-5D) to health care professionals wishing to use it as a measure of health-related quality of life. METHODS: This paper is based on a review of studies using the EQ-5D in Spanish populations which include chronic and critical patients, health care users, and random samples of the general population in Navarra and Catalonia. RESULTS: Results are presented for three aspects of the EQ-5D: the descriptive system, the visual analogic scale, and the EQ-5D tariff. Presence of problems on the descriptive system and lower scores on the visual analogue scale were positively associated with increasing age, being female, lower educational level and social class, presence of chronic conditions, higher levels of restricted activity, visits to a health care professional in the previous 15 days, and hospitalisation during the previous year. The ability of the descriptive system and the visual analogic scale to discriminate between healthy individuals and critical and chronic patients was good. Social tariffs for EQ-5D health states have been obtained based on self-rated health and the rating of hypothetical health states (health states not experienced by the rater). Tariffs for hypothetical health states have been obtained using visual analogic scale and time trade-off techniques. Tariffs also discriminate between healthy and non-healthy subjects, and are a valid reflection of preferences for health states. CONCLUSIONS: The Spanish version of the EQ-5D is a simple, valid and practical measure for its use as an outcome variable both in clinical research and in the allocation of health care resources:

Europe↗
PubMed1998

Using the EuroQoI 5-D in the Catalan general population: feasibility and construct validity.

Spanish and Catalan versions of the EuroQoi 5-D (EQ-5D) were included in the Catalan Health Interview Survey (CHIS) and administered to a randomly selected cross-section of 12,245 individuals from the Catalan general population. This paper analyses the feasibility, convergent validity and construct validity of three parts of the EQ-5D (the descriptive system, the visual analogue scale (VAS) and the Spanish tariff) using the results obtained in the CHIS. The feasibility was assessed by the number of missing responses. The convergent validity was based on the correlations between the EQ-5D scores and the scores on the General Health Questionnaire (GHQ) and on an index of self-perceived overall health. The construct validity was assessed by analysing the degree to which lower scores on the EQ-5D correlated positively with increasing age, being female, being in a lower social class or having a lower level of education and with increasing levels of disability, co-morbidity, restricted activity, mental health problems and poor self-perceived health. A low number of missing responses on the descriptive system and the VAS (1.5%) indicated a high level of acceptance. A marked ceiling effect was found, with 67% of the sample reporting no problem in any EQ dimension. The convergent validity with the GHQ was generally low, though moderate on the mood dimension. Self-perceived overall health correlated moderately to strongly with the mean VAS and tariff values. The positive correlations between lower scores on all three elements of the EQ-5D and increasing age, increasing levels of disability, comorbidity, restricted activity, mental health problems and poor self-perceived health provide some evidence of the instrument's construct validity, as does the fact that women reported more problems than men. Multivariate analyses using the VAS and tariff values as dependent variables and all of the sociodemographic and health variables as independent variables reached R2 values of 0.45 and 0.81, respectively. The Spanish and Catalan versions of the EQ-5D have proved to be feasible and valid for use in health interview surveys.

Adolescent↗
PubMed1998

A model of equivalence in the cultural adaptation of HRQoL instruments: the universalist approach.

The health-related quality of life (HRQoL) literature presents a confused picture of what 'equivalence' in the cross-cultural use of HRQoL questionnaires means and how it can be assessed. Much of this confusion can be attributed to the 'absolutist' approach to the cross-cultural adaptation of HRQoL questionnaires. The purpose of this paper is to provide a model of equivalence from a universalist perspective and to link this to the translation and adaptation of HRQoL questionnaires. The model evolved from reviews of the HRQoL and other literatures, interviews and discussions with researchers working in HRQoL and related areas and practical experience in the adaptation and development of HRQoL instruments. The model incorporates six key types of equivalence. For each type of equivalence the paper provides a definition, proposes various strategies for examining whether and how types of equivalence can be achieved, illustrates the relationships between them and suggests the order in which they should be tested. The principal conclusions are: (1) that a universalist approach to the cross-cultural adaptation of HRQoL instruments requires that six types of equivalence be taken into account; (2) that these are sufficient to describe and explain the nature of the cross-cultural adaptation process; (3) that this approach requires careful qualitative research in target cultures, particularly in the assessment of conceptual equivalence; and (4) that this qualitative work will provide information which will be fundamental in deciding whether to adapt an existing instrument and which instrument to adapt. It should also result in a more sensitive adaptation of existing instruments and provide valuable information for interpreting the results obtained using HRQoL instruments in the target culture.

Algorithms↗
PubMed1998

The influence of ill-health experience on the valuation of health.

Social valuations for health states are potentially useful both in clinical decision-making and in health-resource allocation, but there is some evidence that the experience of illness may affect such valuations. This article compares valuations of hypothetical health states obtained from a sample of chronically ill patients, with valuations obtained from a sample of relatively healthy individuals. The instrument used to obtain these values was the EuroQOL 5D questionnaire (EQ-5D). We found that the EQ-5D values of chronically ill patients differed significantly from the values obtained from healthier individuals, particularly in the case of the more severe health states. Healthy individuals assigned negative values to some hypothetical health states, indicating that they consider them to be worse than death, whereas chronically ill patients assigned positive values to all health states. These results raise difficult questions about whose values should count when health-status measures are incorporated in clinical and economic evaluation, and in particular when deciding upon the allocation of scarce resources.

Activities of Daily Living↗
PubMed1997

Prochlorothrix hollandica PCC 9006: genomic properties of an axenic representative of the chlorophyll a/b-containing oxyphotobacteria.

Prochlorothrix hollandica is an oxygenic photosynthetic prokaryote that differs from the cyanobacteria in having chlorophyll a/b-protein complexes instead of phycobilisomes as major light-harvesting antennae. We report the isolation and culturing of an axenic strain of P. hollandica, available from the Pasteur Culture Collection of Cyanobacteria as strain PCC 9006. The strain has a mean DNA base composition of 51.6 +/- 0.1 mol% G+C and a genomic complexity of 3.37 +/- 0.17 x 10(9) daltons (5,505 kb). A reiterated DNA sequence represents approximately 4.4% of the genome. Restriction enzyme isoschizomers with different sensitivities to base methylation were used to demonstrate that most A residues in the sequence GATC are methylated in P. hollandica DNA and that this methylation increases with culture age. Furthermore, some C residues are methylated, although the specificity of the C methylation system does not match that of well-characterized C methylases. Nucleotide analysis showed that up to approximately 3.5% of both dA and dC residues are methylated in P. hollandica DNA.

Base Pairing↗
PubMed1997

'Equivalence' and the translation and adaptation of health-related quality of life questionnaires.

The increasing use of health-related quality of life (HRQOL) questionnaires in multinational studies has resulted in the translation of many existing measures. Guidelines for translation have been published, and there has been some discussion of how to achieve and assess equivalence between source and target questionnaires. Our reading in this area had led us, however, to the conclusion that different types of equivalence were not clearly defined, and that a theoretical framework for equivalence was lacking. To confirm this we reviewed definitions of equivalence in the HRQOL literature on the use of generic questionnaires in multicultural settings. The literature review revealed: definitions of 19 different types of equivalence; vague or conflicting definitions, particularly in the case of conceptual equivalence; and the use of many redundant terms. We discuss these findings in the light of a framework adapted from cross-cultural psychology for describing three different orientations to cross-cultural research: absolutism, universalism and relativism. We suggest that the HRQOL field has generally adopted an absolutist approach and that this may account for some of the confusion in this area. We conclude by suggesting that there is an urgent need for a standardized terminology within the HRQOL field, by offering a standard definition of conceptual equivalence, and by suggesting that the adoption of a universalist orientation would require substantial changes to guidelines and more empirical work on the conceptualization of HRQOL in different cultures.

Cross-Cultural Comparison↗
PubMed1989

Role of computed tomography in evaluating asbestos related lung disease.

To find how computed tomography (CT) may be effectively used in individuals with suspected asbestos related lung disease 30 men with a history of exposure to asbestos were studied. All subjects underwent high kilovoltage posteroanterior and left lateral chest radiographs and chest CT. Eighteen were randomly selected asbestos workers referred for routine surveillance. The remaining 12 were patients who had been referred for investigation of respiratory symptoms or abnormal routine chest radiograph, or both, and found to have chest radiographic changes compatible with asbestos related lung disease. In the group referred for routine surveillance both pleural shadowing and pulmonary shadowing were shown on CT but not chest radiographs in only one case. Five were thought to have pleural shadowing on chest radiographs but this was confirmed on CT in only one case. All 12 patients referred for investigation showed pleural shadowing on chest radiographs; this was confirmed in all cases on CT which also showed unsuspected pulmonary shadowing in five cases. These findings suggest that it is not appropriate to use chest CT routinely in all asbestos workers referred for routine surveillance. When CT is used selectively in those with pleural shadowing on plain chest radiography, however, it is helpful in refuting or confirming the presence of pleural disease and may show unsuspected pulmonary shadowing.

Adolescent↗
PubMed1984

Photosynthetic mutants of the cyanobacteria Synechocystis sp. strains PCC 6714 and PCC 6803: sodium p-hydroxymercuribenzoate as a selective agent.

Among a wide range of potential selective agents examined, sodium p-hydroxymercuribenzoate successfully enriched for mutants of Synechocystis sp. strains PCC 6714 and 6803 defective in photosynthesis. When both photosystems I and II were operating, viability of wild-type cells decreased to between 5 X 10(-5) and 1 X 10(-6) after 5 h of incubation with 500 microM p-hydroxymercuribenzoate (strain 6714), and after 8 h with 200 microM (strain 6803). Between 0.1 and 0.5% of the survivors were stable mutants defective in different steps of photosynthesis. The compound was not mutagenic. It was less toxic to cells grown chemoheterotrophically in the dark or photoheterotrophically in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. p-Hydroxymercuribenzoate therefore killed only cells which were performing photosynthesis at high rates, thereby specifically selecting for mutants deficient in this process.

Chlorophyll↗
PubMedDate not supplied

A comparison of United Kingdom and Spanish general population time trade-off values for EQ-5D health states.

Few studies have compared preference values for health states obtained in different countries. The present study compared Spanish and United Kingdom (UK) time trade-off values for EuroQol-5D health states. The same preference elicitation protocol was followed in both countries. Differences in values for 43 health states rated directly were analyzed using t tests, and regression coefficients generated by random effects modeling were compared by aggregating the 2 value sets and using dummy variables to analyze country effect by dimension and level of severity. For the milder health states, Spanish and UK value assignation was similar; for intermediate health states, Spanish values were both higher and lower than UK values, whereas for health states worse than death, UK values were generally higher than Spanish values. There were statistically significant differences (P < 0.01) in values for 34.9% of health states rated directly, and some preference reversals between countries. UK raters ascribed greater importance to dimensions of pain/discomfort and anxiety/depression, whereas Spanish raters placed more importance on functional dimensions of mobility and self-care. Further analysis is required to determine how these differences affect cost-effectiveness and cost-utility analyses.

Adolescent↗
PubMedDate not supplied

[Financial assessment of device for the preparation of intravenous mixtures in hospital pharmacy].

OBJECTIVE: To financially assess a device for the preparation of intravenous mixtures (DPIVM) --Grifill system-- such as IV gammaglobulin, salbutamol, ondansetron/dexametasone, cisplatin rehydrating solution and mesna. MATERIAL AND METHODS: The most relevant resources used in the preparation and rebottling of each of the above-mentioned intravenous mixtures (for both the DPIVM and the commonly used alternative system) are assessed, as well as unitary costs (obtained from six Spanish hospitals enrolled), and an approach to the real cost by system used is obtained. A sensitivity analysis is performed considering most influencing variables. Results are calculated for one month of system operation. RESULTS: For IV gammaglobulin, mesna, salbutamol, ondansetron/dexametasone and polyionic solutions DPIVM resulted in financial benefit, but it did not in the preparation of cisplatin rehydrating solution. CONCLUSIONS: An individualized study in each center is needed to achieve reliable financial data on the system's profitability at hospital pharmacy departments. DPIVM may allow significant financial savings in centers and hospital departments using high-cost pharmaceuticals susceptible of customized dosing --e. g., IV gammaglobulin, other blood derivatives, monoclonal antibodies and/or antibiotics-- or intravenous mixtures requiring pharmaceuticals usually purchased directly from the manufacturer that may be prepared from low-cost raw materials (for instance, salbutamol and polyionic solution) requiring high-quality manipulation (e. g., sterility and precision).

Albuterol↗