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Biomedical subjects

M Herdman

Publications and source records attributed to M Herdman.

At least 19 recordsLinked to original sources
PubMed2006

[Reliability and validity of the Spanish version of the health and quality-of-life questionnaire, the Vecú et Santé Perçue de l'Adolescent (VSP-A)].

OBJECTIVE: To assess the psychometric properties of the Spanish version of the Vecú et Santé Perçue de l'Adolescent (VSP-A) in terms of reliability and validity. DESIGN: Cross-sectional study. SETTING: Pilot study parallel to the European Kidscreen project. Two secondary schools, one public and one private, were selected for their suitability in Barcelona and Gerona (Catalonia, Spain). The sample unit was the classroom. PARTICIPANTS: A sample of 354 adolescents aged 12 to 18 years old was selected. MAIN MEASUREMENTS: The Spanish VSP-A questionnaire was administered, and again a week later to check its test-retest stability. The KINDL questionnaire was administered in parallel. RESULTS: The response rate was 82% (n=291). The Spanish version of the VSP-A showed good internal consistency and acceptable test-retest reliability (Cronbach's alpha: 0.69-0.92, intraclass correlation coefficient [ICC]: 0.69-0.74) in most domains. Domains measuring a similar concept in the VSP-A and KINDL had closer correlation coefficients than those measuring different constructs (P<.05), which demonstrates its convergent validity. Girls had worse self-perceived health than boys (lower vitality, physical and emotional well-being and self-esteem, and a lower general score on the VSP-A; p<.01). These differences were more obvious in older teens (16-18 years old). CONCLUSIONS: The Spanish VSP-A showed good psychometric properties and results were consistent with the original French version. The results mean we have an adequate HRQL instrument for teens and for use in primary care and public health.

Adolescent↗
PubMed2006

A study examining inter- and intrarater reliability of three scales for measuring severity of psoriasis: Psoriasis Area and Severity Index, Physician's Global Assessment and Lattice System Physician's Global Assessment.

BACKGROUND: There is a lack of consensus as to the best way of monitoring psoriasis severity in clinical trials. The Psoriasis Area and Severity Index (PASI) is the most frequently used system and the Physician's Global Assessment (PGA) is also often used. However, both instruments have some drawbacks and neither has been fully evaluated in terms of 'validity' and 'reliability' as a psoriasis rating scale. The Lattice System Physician's Global Assessment (LS-PGA) scale has recently been developed to address some disadvantages of the PASI and PGA. OBJECTIVES: To evaluate the inter-rater and intrarater reliability of the PASI, PGA and LS-PGA. METHODS: On the day before the study, 14 dermatologists (raters), with varied experience of assessing psoriasis, received detailed training (2.5 h) on use of the scales. On the study day, each rater evaluated 16 adults with chronic plaque psoriasis in the morning and again in the afternoon. Raters were randomly assigned to assess subjects using the scales in a specific sequence, either PGA, LS-PGA, PASI or PGA, PASI, LS-PGA. Each rater used one sequence in the morning and the other in the afternoon. The primary endpoint was the inter-rater and intrarater reliability as determined by intraclass correlation coefficients (ICCs). RESULTS: All three scales demonstrated 'substantial' (a priori defined as ICC > 80%) intrarater reliability. The inter-rater reliability for each of the PASI and LS-PGA was also 'substantial' and for the PGA was 'moderate' (ICC 75%). CONCLUSIONS: Each one of the three scales provided reproducible psoriasis severity assessments. In terms of both intrarater and inter-rater reliability values, the three scales can be ranked from highest to lowest as follows: PASI, LS-PGA and PGA.

Adult↗
PubMed2003

Validation of the Spanish version of the Liver Disease Quality of Life questionnaire in transplant patients.

OBJECTIVE: Our aim was to validate Spanish and Catalan versions of the Liver Disease Quality of Life questionnaire (LDQOL) for use in liver transplant patients. METHODS: The LDQOL consists of the SF-36 generic measure of health-related quality of life (HRQOL) and 12 disease-specific dimensions for liver disease patients. The Spanish and Catalan versions of the questionnaire were administered to 138 patients with a liver transplant. Cronbach's alpha coefficients (CAC) were used to test the internal consistency of disease-specific scales. Test-retest reliability was calculated using the Intraclass Correlation Coefficient (ICC) in a sub-group of 41 patients who completed the questionnaire on two occasions 1 to 2 weeks apart. Validity was analysed by determining the instrument's capacity to discriminate between patient groups classified according to years since transplant, disease etiology, and symptom severity. Ceiling and floor effects were also calculated. RESULTS: Internal consistency in the disease-specific dimensions was acceptable or good (CACs 0.60-0.97), as was test-retest reliability in all dimensions (statistically significant CCIs of 0.62-0.89), except the symptoms dimension (CCI=0.46, P<.05). Few differences were found in disease-specific dimension scores between patients classified according to number of years since transplant or etiology, but differences were found in some dimensions according to symptom severity. Moderate to severe ceiling effects were found in several disease-specific dimensions. CONCLUSIONS: The Spanish and Catalan versions of the LDQOL may be useful for measuring HRQOL in this population, though it will be important to investigate further the instrument's sensitivity to change.

Activities of Daily Living↗
PubMed2003

[Transcultural adaptation of the Liver Disease Quality of Life instrument (LDQOL 1.0) for its use in the Spanish population].

Instruments of health-related quality of life (HRQOL) help us to interpret the results of treatments and health interventions. In Spain there is no HRQOL instrument specifically designed for use in patients with liver disease or to measure the effect of interventions such as liver transplantation. The Liver Disease Quality of Life (LDQOL 1.0) questionnaire is an American instrument developed for use in these patients. The aim of this study was to produce an appropriate version of this questionnaire for use in Spain. Cultural adaptation was performed in 3 phases: a) modification for use in Spain of a Hispanic version of this questionnaire supplied by the original authors; b) back-translation to English of a new version of the questionnaire and comparison with the original version in English, and c) a pilot test in a small sample of patients. In the first phase consisting of revision of the Hispanic version, the changes were mainly linguistic due to cultural and idiomatic differences. The validated Spanish version of the SF-36 was directly incorporated and items that could be of interest to local investigators were added. Few changes were made in the second phase of the process: changes involved an item on the appearance of feces and another item on taking naps. In the final phase, various changes suggested by the patients were introduced. Before applying the new version of the LDQOL 1.0 in clinical studies in Spain, its psychometric properties (its reliability, validity and sensitivity to change) must be verified in a subsequent validation study.

Cross-Cultural Comparison↗
PubMed2002

Development of a short osteoporosis quality of life questionnaire by equating items from two existing instruments.

This study aimed to develop a short Osteoporosis-Specific Quality of Life Questionnaire based on the assemblage (equating) of the items of two existing questionnaires (OQLQ and QUALEFFO). For this purpose, each questionnaire was administered by random assignment to a different group of female patients (OQLQ, n = 172; QUALEFFO, n = 166) with vertebral fractures due to osteoporosis. A common anchor test (SF-36) was also given to both groups. Seven different sets of OQLQ-QUALEFFO common items were defined by inspecting their own correlation with the scores of the eight dimensions of the SF-36. Within each set, equating consisted in connecting the OQLQ and QUALEFFO through their link with the SF-36. Equating was carried out through the Rasch mathematical model. Quantitative (item statistics) and qualitative reductions (expert opinion) of the equated sets resulted in a 16-item questionnaire. Although the new instrument requires further empirical validation, it provides a promising alternative to currently existing longer questionnaires for use in clinical practice.

Activities of Daily Living↗
PubMed2002

Expert consensus in the development of a European health-related quality of life measure for children and adolescents: a Delphi study.

AIM: To determine the level of consensus among experts regarding content, structure and sources of content for a new European measure of health-related quality of life in children and adolescents. METHODS: A three-round Delphi questionnaire was sent by e-mail to 24 experts in quality of life measurement in 9 European countries. Consensus was considered reached when > 90% of experts either agreed or disagreed with a given statement, or where median scores were over 6 on a scale of 1-10, and score dispersion was within predefined limits. RESULTS: Completed questionnaires were received from 20 panellists in each round. It was agreed that the new instrument should be a multidimensional, profile measure with 30-49 items covering 5-8 dimensions, which should take no more than 10-15 min to complete. Agreement was also reached on 8 specific dimensions to include in the questionnaire (psychological well-being, self-esteem, body image, cognitive functioning, mobility, energy/vitality, social relations, family/home function). Consensus was against the use of individualized questionnaires. Focus groups with children, parents and workers in the field, literature and instrument reviews were considered appropriate sources for content. CONCLUSION: Using a Delphi method in this way for the first time showed it to be a feasible and useful method for establishing a conceptual and operational framework for the Kidscreen questionnaire.

Adolescent↗
PubMed2001

Using the EuroQol-5D to measure changes in quality of life 12 months after discharge from an intensive care unit.

OBJECTIVE: To compare changes in the health-related quality of life (HRQOL) of critical care patients by diagnostic category. DESIGN: Prospective, cohort study. HRQOL assessed 3 months before admission and 1 year after discharge from the intensive care unit (ICU). Patients were classified as: trauma injury (TI), scheduled surgery (SS), unscheduled surgery (US), and other medical conditions (MC). SETTING: Department of Intensive Medicine, University Hospital of Bellvitge, Barcelona, Spain. PATIENTS: Three hundred and thirty-four patients admitted to ICU from October 1994 to June 1995 (62 TI patients, 181 SS patients, 19 US patients, and 72 MC patients). INTERVENTIONS: Surgical and medical procedures. MEASUREMENTS AND RESULTS: Changes in HRQOL varied considerably between diagnostic categories, with TI patients having significantly worse HRQOL one year after discharge from the ICU compared to 3 months prior to admission [change in median EQ Visual Analogue Scale (EQ-VAS) score from 100 to 65, P<0.001], and SS patients reporting improved HRQOL (change in median EQ-VAS scores from 60 to 75, P<0.001). Slight deterioration was observed in the other two diagnostic categories. Twelve months after discharge, the EQ dimension in which the largest proportion of patients in all groups reported problems was usual activities (47% of SS and US patients; 69% of TI patients). Using proxy scores at baseline or follow-up had little effect on results. CONCLUSIONS: The degree and direction of change in ICU patients' HRQOL 1 year after discharge depends considerably on diagnostic category. Proxy responses can be reliably used with the EQ-5D when measuring change in HRQOL.

Adult↗
PubMed2001

Nonribosomal peptide synthetase genes occur in most cyanobacterial genera as evidenced by their distribution in axenic strains of the PCC.

Previous studies largely carried out with environmental samples or axenic and non-axenic cultures suggested that cyanobacteria may be a rich source of hitherto unexplored bioactive compounds. This has been confirmed in the present study by a screening of 146 axenic strains from the Pasteur Culture Collection (PCC) of cyanobacteria. Use of degenerate PCR primers, designed on the basis of conserved sequence motifs in the aminoacyl-adenylation domain of peptide synthetases, revealed the presence of the corresponding genes in the majority (75.3%) of the strains examined. Among unicellular cyanobacteria, only Chamaesiphon sp. strain PCC 6605, two strains of Gloeocapsa and most Microcystis isolates (22 out of 24) contained these genes; no amplicons were detected for any members of the genera Cyanothece, Gloeobacter and Gloeothece and the genetically diverse representatives of Synechococcus and Synechocystis. By contrast, eight out of ten pleurocapsalean members, 16 out of 25 oscillatorian strains, and all but two of the 63 filamentous heterocystous cyanobacteria tested gave positive amplification results. This information will be highly valuable for further exploring the corresponding cyanobacterial peptides and for elucidating the bioactivity of such non-ribosomally synthesized molecules.

Cyanobacteria↗
PubMed2001

Scyptolin A and B, cyclic depsipeptides from axenic cultures of Scytonema hofmanni PCC 7110.

Two novel cyclic depsipeptides were isolated from axenic cultures of the terrestrial cyanobacterium Scytonema hofmanni PCC 7110 and designated scyptolin A and B. Amino acid analyses in context with mass and 1H/13C NMR spectroscopies revealed a composition typical for heterologous cyanopeptolins but containing the uncommon residue 3'-chloro-N-methyl-Tyr (cmTyr) and a unique sidechain. Scyptolin A and B both consist of the N-acylated peptide But(1)-Ala(2)-Thr(3)-Thr(4)-Leu(5)-Ahp(6) (3-amino-6-hydroxy-2-oxo-1-piperidine)-Thr(7)-cmTyr(8)-Val(9), which forms a 19-membered ring by esterification of the carboxyl of Val(9) with the hydroxyl of Thr(4). In scyptolin B, the hydroxyl of the Thr(3) residue is additionally esterified with N-butyroyl-Ala. Both scyptolin A and B exhibit selective inhibition of porcine pancreatic elastase in vitro with IC(50) values of 3.1 microg/ml.

Amino Acid Sequence↗
PubMed2001

The importance of health-related quality-of-life data in determining the value of drug therapy.

BACKGROUND: The rapid evolution of outcomes research during the last decade has led to increasing emphasis on measures of health-related quality of life (HRQOL). However, the relatively recent advent of these measures makes it difficult to decide how much weight to attribute to them in decisions about the value of drug therapy. OBJECTIVE: The aim of this article is to discuss the factors that affect the relative importance of HRQOL data in determining the value of drug therapy. CONCLUSIONS: The relative importance of HRQOL data depends on the type of condition and the type of treatment. In chronic conditions, HRQOL may be considered a primary measure of efficacy. In acute conditions, HRQOL is not likely to be a primary efficacy measure, although excluding HRQOL measures may lead to an underestimation of treatment effects. Measures of HRQOL are also likely to be important in the assessment of palliative treatments and, to some extent, preventive treatments (primarily in the measurement of adverse effects). HRQOL measures will be less important in the assessment of curative treatments because these types of treatment are most relevant in acute conditions.

Drug Therapy↗
PubMed2001

Effect of mode of administration on I-PSS scores in a large BPH patient population.

OBJECTIVES: The International Prostate Symptoms Score (I-PSS) was designed to be self-administered to patients with benign prostatic hyperplasia. This study tested for a possible mode of administration effect on the I-PSS and assessed the reliability of the I-PSS over time when modes of administration varied. METHODS: Benign prostatic hyperplasia patients over 50 years of age were recruited at 52 Spanish centres. The I-PSS was administered on two occasions 1 month apart. Patients were sequentially classified into groups A-D according to the mode of administration (S = self-administered, I = interview administered) at the two visits (A = S-S, B = S-I, C = I-S, and D = I-I). The intraclass correlation coefficient was used to assess test-retest reliability, and multiple regression analysis was used to test the effects of the mode of administration and the visit number on I-PSS scores. RESULTS: 926 patients (mean age 66 years) were evaluated. The mean I-PSSs symptoms score at visit 1 in groups A-D were, respectively, 13.19, 13.57, 12.06, and 12.29. Multiple regression analysis between-group scores were 0.93 points higher when the I-PSS was self-administered and 1.98 points lower at the second visit. The intraclass correlation coefficients were: group A = 0.77, group B = 0.70, group C = 0.67, and group D = 0.76. CONCLUSIONS: Interview administration of the I-PSS results in slightly lower scores. The reliability is higher when the same mode of administration is used at two recurrent visits.

Age Factors↗
PubMed2000

A new appraisal of the prokaryotic origin of eukaryotic phytochromes.

The evolutionary origin of the phytochromes of eukaryotes is controversial. Three cyanobacterial proteins have been described as "phytochrome-like" and have been suggested to be potential ancestors of these essential photoreceptors: Cph1 from Synechocystis PCC 6803, showing homology to phytochromes along its entire length and known to attach a chromophore; and PlpA from Synechocystis PCC 6803 and RcaE from Fremyella diplosiphon, both showing homology to phytochromes most strongly only in the C-terminal region and not known to bind a chromophore. We have reexamined the evolution of the photoreceptors using for PCR amplification a highly conserved region encoding the chromophore-binding domain in both Cph1 and phytochromes of plants and have identified genes for phytochrome-like proteins (PLP) in 11 very diverse cyanobacteria. The predicted gene products contain either a Cys, Arg, Ile, or Leu residue at the putative chromophore binding site. In 10 of the strains examined only a single gene was found, but in Calothrix PCC 7601 two genes (cphA and cphB) were identified. Phylogenetic analysis revealed that genes encoding PLP are homologues that share a common ancestor with the phytochromes of eukaryotes and diverged before the latter. In contrast, the putative sensory/regulatory proteins, including PlpA and RcaE, that lack a part of the chromophore lyase domain essential for chromophore attachment on the apophytochrome, are only distantly related to phytochromes. The Ppr protein of the anoxygenic photosynthetic bacterium Rhodospirillum centenum and the bacterial phytochrome-like proteins (BphP) of Deinococcus radiodurans and Pseudomonas aeruginosa fall within the cluster of cyanobacterial phytochromes.

Amino Acid Sequence↗
PubMed2000

Prochlorococcus marinus Chisholm et al. 1992 subsp. pastoris subsp. nov. strain PCC 9511, the first axenic chlorophyll a2/b2-containing cyanobacterium (Oxyphotobacteria).

The formal description of Prochlorococcus marinus Chisholm et al. 1992, 299 was based on the non-axenic nomenclatural type, strain CCMP 1375T. The purification and properties of the axenic strain PCC 9511, derived from the same primary culture (SARG) as the type species, are reported here. Prochlorococcus PCC 9511 differs from the latter in possessing horseshoe-shaped thylakoids, exhibiting a low chlorophyll b2 content and lacking phycoerythrin, but shares these phenotypic properties with Prochlorococcus strain CCMP 1378. This relationship was confirmed by 16S rRNA sequence analyses, which clearly demonstrated that the axenic isolate is not co-identic with the nomenclatural type. Strain PCC 9511 has a low mean DNA base composition (32 mol% G+C) and harbours the smallest genome of all known oxyphotobacteria (genome complexity 1.3 GDa = 2 Mbp). Urea and ammonia are the preferred sources of nitrogen for growth, whereas nitrate is not utilized. Several different organic phosphorus compounds efficiently replace phosphate in the culture medium, indicative of ecto-phosphohydrolase activity. In order to distinguish strain PCC 9511 from the nomenclatural type, a new subspecies is proposed, Prochlorococcus marinus Chisholm et al. 1992 subsp. pastoris subsp. nov.

Bacterial Typing Techniques↗
PubMed2000

[The measurement of health related quality of life].

The measurement of health-related quality of life (HRQOL) plays a very important role in the study of health outcomes, particularly in effectiveness studies. Nevertheless, the nature of these studies implies a series of challenges in the use of HRQOL instruments, due to the type of comparisons made, the heterogeneity of subjects included in terms of both the presence of comorbid conditions and the ability to understand and complete questionnaires, and because there is a need to collect the data in conditions of usual clinical practice. The aim of this paper is to discuss some of these issues, as well as other topics of current interest in the field, such as the use of individualized measures, applications of Item Response Theory, and response shift phenomenon research. With regard to the use of HRQOL measures in effectiveness studies, the main conclusions are that: a) instrument selection probably needs to be even more careful than in controlled clinical trials, and needs to take into account time pressures and variability in patients' ability to respond; b) that instrument selection should centre on the use of disease-specific measures; c) that generic measures may play an important role in capturing the broader effects of co-morbidity, and may be useful in controlling certain types of bias, and d) that more comparisons are required between disease-specific instruments for the same condition, particularly with respect to their discriminative power and their sensitivity to change.

Cost of Illness↗
PubMed1999

Inconsistent responses in three preference-elicitation methods for health states.

Values for health states obtained from the general population can be used in the development of cost-utility algorithms such as Quality Adjusted Life Years (QALYs) to aid in resource allocation decisions. These values are obtained using methods such as the visual analogue scale, the time trade-off or the standard gamble. However, all of these methods suffer, to some extent, from the problem of inconsistent responses. In this paper, we examine the degree to which three preference-elicitation methods-ranking, VAS and TTO--produce inconsistent responses, the effect of sociodemographic and health variables on the numbers of inconsistencies produced, and the effect of including inconsistent responses on the ordering of health states in EQ-5D VAS and TTO tariffs. Health states valued were a sub-set of 43 health states generated by the EuroQol-5D instrument, which were valued as part of a larger study to obtain a tariff of VAS and TTO values for use with the Spanish version of the EQ-5D. Two types of inconsistency--internal and criterion inconsistency were tested, and both the numbers of inconsistencies produced by each method, and the 'size' of those inconsistencies, i.e. the distance in terms of severity between health states rated inconsistently, were tested. The study showed that although the TTO produces higher numbers of inconsistent responses, the numbers of inconsistent responses in all methods were low, and did not affect rankings in the final tariff of values. Older respondents and those with lower levels of education produced significantly higher numbers of inconsistencies, though health characteristics were not significant. On the ranking and VAS methods, the number of inconsistencies doubled between the two interviewers. Efforts should be made to reduce inconsistencies, particularly among older and lesser educated respondents. Future research should concentrate on determining how inconsistencies might affect the values assigned to health states in the final tariff, and not simply the order of those states.

Adult↗
PubMed1999

Feasibility, validity and test-retest reliability of scaling methods for health states: the visual analogue scale and the time trade-off.

The feasibility, validity and reliability of the Time Trade-Off (TTO) and Visual Analogue Scale (VAS) methods in obtaining preference values for health states were compared in a random sample of the Spanish population (n = 294). Respondents valued 43 EuroQol-5D health states in face-to-face interviews. Convergent validity was assessed by examining the relationship between values, and the effect of sociodemographic and health variables on values was used as a means of assessing construct validity. Test-retest reliability was analysed in a subgroup of 50 respondents, using the intraclass correlation coefficient (ICC) and generalisability theory. Rates of non-response and missing data were low on both methods, though the VAS took considerably less time to administer. VAS and TTO values correlated highly (r = 0.92), though there were differences in the ordering of health states between methods, and in the number of health states rated worse than death. VAS values were compressed into a considerably smaller valuation space than TTO values. Respondents in higher educational categories assigned higher TTO values to 12 health states. Mean ICCs (95% CI) at individual level were 0.90 (0.88-0.92) and 0.84 (0.81-0.87) for the VAS and TTO, respectively. Generalisability analysis showed variance due to time to be 0 for both methods. In conclusion, the VAS was more feasible and slightly more reliable than the TTO, whilst doubt can be cast on the degree of convergent validity existing between the two methods. The compression of VAS values means that the TTO is likely to discriminate better between health states, and it may have greater construct validity if results from larger samples confirm that there are genuine differences between sociodemographic subgroups.

Adult↗