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Biomedical subjects

Luis Prieto

Publications and source records attributed to Luis Prieto.

At least 19 recordsLinked to original sources
PubMed2006

Effect of challenge method on sensitivity, reactivity, and maximal response to methacholine.

BACKGROUND: Recent data suggest that the tidal breathing method may produce methacholine provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20) values significantly lower than the dosimeter method; however, the effect of the challenge method on the shape of the concentration-response curve has not been investigated. OBJECTIVE: To determine the effect of the challenge method on sensitivity, reactivity, and maximal response to methacholine. METHODS: We measured airway responsiveness to methacholine using dosimeter and tidal breathing methods in 30 individuals with suspected asthma. Concentration-response curves were characterized by their PC20 (sensitivity), slope (reactivity), and, if possible, level of plateau. RESULTS: Dosimeter PC20 values were significantly higher than tidal breathing values (geometric mean, 8.9 and 5.2 mg/mL, respectively); the mean difference in PC20 values obtained using each method was 0.78 doubling concentrations (P = .01). The mean slopes were 22.7%/log mg/mL using the tidal breathing method and 24.9%/log mg/mL using the dosimeter method; the mean difference in the slopes obtained using each method was -2.17%/log mg/mL (P = .18). In 10 individuals who showed a plateau with the 2 methacholine challenge tests, the mean level of plateau was 19.8% using the tidal breathing method and 19.5% using the dosimeter method; the mean difference in the plateau values obtained with each method was 0.3% (P = .87). CONCLUSIONS: Although the tidal breathing method produces methacholine PC20 values significantly lower than the dosimeter method, both methods provide similar values for slope and level of plateau. These results suggest that the technical factors that affect methacholine sensitivity and the shape of the curve are different.

Administration, Inhalation↗
PubMed2006

The effect of challenge method on sensitivity and reactivity to adenosine 5'-monophosphate in subjects with suspected asthma.

BACKGROUND: The following two methods of inhalation challenge have been used to determine the airway responsiveness: the tidal-breathing method; and the dosimeter method. The objective of the study was to determine the influence of the challenge method on the response to adenosine 5'-monophosphate (AMP). METHODS: This study measured airway responsiveness to AMP by dosimeter and tidal-breathing methods in 25 subjects with suspected asthma. The two AMP challenges were conducted in random order, on separate days, at the same time of day, at intervals of 1 to 5 days. Concentration-response curves were characterized by the provocative concentration of a substance causing a 20% fall in FEV1 (PC20) and slope. RESULTS: The dosimeter PC20 values were significantly higher than the tidal-breathing PC20 values, with geometric mean (95% confidence interval [CI]) values of 50.35 mg/mL (95% CI, 19.50 to 129.72 mg/mL) and 28.97 mg/mL (95% CI, 11.99 to 69.98 mg/mL; p = 0.02), respectively. The mean difference in the PC20 values obtained with each method was 0.80 doubling concentrations (95% CI, 0.16 to 1.44 doubling concentrations). The mean values for the slope were 17.0%/log mg/mL (95% CI, 12.5 to 21.5 mg/mL) with the tidal breathing method and 13.8%/log mg/mL (95% CI, 9.0 to 18.7 mg/mL; p = 0.03) with the dosimeter. CONCLUSIONS: The tidal-breathing method produces AMP PC20 values that are significantly lower than the dosimeter method and slope values that are significantly higher than the dosimeter method. These data suggest that the results obtained with each method of testing may not be comparable.

Adenosine Monophosphate↗
PubMed2005

Development and validation of a quality of life questionnaire for patients with colostomy or ileostomy.

BACKGROUND: Quality of life of stoma patients is increasingly being addressed in clinical trials. However, the instruments used in the majority of these studies have not been validated specifically for stoma patients. The aim of this paper is to describe the development and validation of a quality-of-life instrument, "Stoma-QOL", specifically for patients with colostomy or ileostomy. METHODS: Potential items were formulated in English on the basis of the results of a series of semi-structured interviews with 169 adult stoma patients. The process resulted in a preliminary 37-item version, which was translated into French, German, Spanish and Danish, and administered repeatedly to 182 patients with colostomy or ileostomy. A psychometric selection of items was performed through Rasch Analysis. The measurement properties of the final questionnaire version were subsequently tested. RESULTS: The 20 items in the final questionnaire covered four domains--sleep, sexual activity, relations to family and close friends, and social relations to other than family and close friends. These items were found to define a unidimensional variable according to Rasch specifications (Infit MNSQ < 1.3). Internal consistency reliability calculated as Cronbach's alpha was 0.92, i.e., highly reliable. Spearman's correlation coefficients of scores across times of administration was > 0.88 (p < 0.01), indicating a high test-retest reliability. Item calibrations by country calculated as ICC were 0.81 (0.67-0.91 95% CI), confirming cross-cultural comparability across the European countries included in the study. CONCLUSION: Given the adequacy of the metric properties of the Stoma-QOL suggested by the psychometric analyses, this study confirms the suitability of the instrument in clinical practice and in clinical research.

Adaptation, Psychological↗
PubMed2005

Heart failure in the elderly: age-related differences in clinical profile and mortality.

BACKGROUND: Age influence in the prognosis in unselected patients with heart failure has not been widely studied. AIMS: To evaluate possible differences in clinical profile and outcome of patients hospitalized with HF according to age. METHODS AND RESULTS: During 1996, a total of 1065 hospital in-patients had confirmed heart failure, with follow-up data through 2002. Patients were separated in two groups < or = 75 and > 75 years of age. Older patients were less frequently men (32 vs. 52%) and had a higher prevalence of previous stroke (14 vs. 10%). Echocardiography was performed less frequently in older patients (55% vs. 78%) and normal systolic function (55 vs. 40%), and aortic stenosis (12 vs. 7%) were more prevalent. They received less anticoagulants (11 vs. 43%) and beta-blockers (2 vs. 7%), while the opposite happened with aspirin (32 vs. 23%) and diuretics (88 vs. 80%). During follow-up, 507 patients died: 55.9% vs. 38.5%. Being > 75 years of age was the strongest predictor of mortality HR: 1.7, CI 95% 1.5-2.1, P < 0.0001. CONCLUSION: Patients with 76 or more years admitted with HF have a different clinical profile. Echocardiography, oral anticoagulation and beta-blockers were underused in these patients. Age was the strongest predictor of long-term mortality.

Age Factors↗
PubMed2005

Primary chemotherapy with cyclophosphamide, methotrexate, and 5-fluorouracil in operable breast carcinoma.

BACKGROUND: Primary chemotherapy (PC) is becoming an accepted practice to treat large tumors to avoid mastectomies and as a surrogate of outcome. METHODS: A series of 305 patients with tumors >3 cm with T2-3N0-1M0 classification were treated with a multimodal approach that consisted of 3 courses of primary cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) followed by appropriate local treatment and 3 more courses of CMF or 4 courses of doxorubicin. Response was assessed by mammography. RESULTS: The overall response rate was 48% (a 3% pathologic complete response rate). Conservative surgery was achieved in 79.64% of the patients with a low rate of local disease recurrences (5%). Toxicity was minimal. With a median follow-up of 104 months, the 8-year disease-free survival (DFS) rate was 57.63% and the 8-year overall survival (OS) was 67.65%. The DFS and OS rates for patients with a clinical response were significantly longer, i.e., 70% (P=0.0048) and 90% (P=0.0042), respectively. CONCLUSIONS: PC with CMF was feasible. A high rate of breast-conservative surgery was achieved. The current results stressed the value of PC to increase conservative surgery and as a predictor of outcome.

Adult↗
PubMed2005

Effect of fluticasone propionate-salmeterol therapy on seasonal changes in airway responsiveness and exhaled nitric oxide levels in patients with pollen-induced asthma.

BACKGROUND: There has been concern that in allergic asthmatic patients there might be an interactive effect on inflammation between regular salmeterol use and exposure to allergens, resulting in increased airway responsiveness. OBJECTIVE: To determine the effects of salmeterol on allergen-induced changes in airway responsiveness and exhaled nitric oxide (ENO) levels in allergic asthmatic patients concomitantly taking inhaled corticosteroids. METHODS: Forty-two asthmatic patients sensitized to pollen allergens were randomly allocated to treatment with fluticasone propionate-salmeterol (n=21) or fluticasone propionate alone (n=21). Spirometry, the methacholine provocation concentration causing a 20% decline in forced expiratory volume in 1 second (PC20), the adenosine 5'-monophosphate (AMP) PC20, and ENO levels were measured before and at the height of the pollen season after 6 weeks of treatment. RESULTS: Changes in the methacholine PC20, the AMP PC20, and ENO levels were not significantly different between treatment groups. No significant changes in the AMP PC20 were observed among the fluticasone propionate-salmeterol and fluticasone propionate groups during natural pollen exposure. However, a significant increase in the methacholine PC20 was observed in the fluticasone propionate-salmeterol group (P = .03) and in the fluticasone propionate group (P = .04); ENO concentrations decreased significantly in both groups during natural allergen exposure (P = .009 and .005). CONCLUSIONS: In patients with pollen-induced asthma, treatment with either fluticasone propionate or fluticasone propionate-salmeterol is associated with significant reductions in methacholine responsiveness and ENO concentrations, even during natural pollen exposure. Furthermore, at least in patients with mild asthma, natural allergen exposure and the regular use of fluticasone propionate-salmeterol are not associated with a greater increase in ENO levels and airway responsiveness than natural allergen exposure and fluticasone propionate use alone.

Adenosine Monophosphate↗
PubMed2005

Phenol-containing saline solution as a diluent for adenosine 5'-monophosphate in bronchial challenge testing.

OBJECTIVES: To investigate the effect of dissolving adenosine 5'-monophosphate (AMP) with phenol-containing saline solution on the stability and the bronchoconstrictive properties of this indirect agonist. METHODS: Eleven subjects with asthma well controlled with short-acting inhaled beta2-agonists as required or with inhaled corticosteroids were studied. Bronchial challenge tests with AMP dissolved with either normal saline solution or saline solution containing 0.4% phenol were performed on separate days. Furthermore, to assess the potential influence of the phenol-containing saline solution on the stability of the bronchoconstrictor agent, AMP solutions in concentrations of 40 microg/mL and 400 microg/mL were prepared in saline solution and phenol-containing saline solution and, after 30 min, the AMP levels were determined by high-performance liquid chromatography (HPLC) assay. RESULTS: The geometric mean AMP provocative concentration causing a 20% fall in FEV1 (PC20) was 13.49 mg/mL (95% confidence interval [CI], 6.76 to 26.91) for the saline solution method, and AMP PC20 for the saline solution with phenol method was 8.91 mg/mL (95% CI, 3.39 to 23.44) [p = 0.18]. No significant differences were found between the concentrations of AMP made in saline solution compared to those made in phenol-containing saline solution measured by HPLC. CONCLUSION: These observations indicate that normal saline solution with or without phenol can be used as the diluent for AMP. However, since a potential risk with AMP of industrial sources is the bacterial contamination, adding a preservative such as phenol to a saline solution diluent might be recommended.

Adenosine Monophosphate↗
PubMed2005

Frequent mistakes in the statistical inference of biomedical data.

Although there is a plethora of books, reviews and articles defining the meaning of the p value, many investigators make errors when reaching conclusions from their work based on this p value. Most report their data using rigid sentences such as "the results are not statistically significant, p > 0.05", frequently misunderstood by the authors and the readers. Many professionals are not aware of their limitations in this field rendering the problem even more complicated. In this article we include advice from experts against mistakes frequently made by investigators, such as the plea made by Rothman that a correct interpretation of the data should not be replaced by sentences such as "statistically significant" or "statistically non-significant". Detailed comments on the more frequent mistakes as well as the reasons for their appearance and persistence during the decades are presented. Finally, a comprehensive explanation of the p value is included, to emphasize that to avoid these mistakes there is no need to learn the mathematical basis of tests but that logic alone would suffice.

Biomedical Research↗
PubMed2004

Mortality impact of extreme winter temperatures.

During the last few years great attention has been paid to the evaluation of the impact of extreme temperatures on human health. This paper examines the effect of extreme winter temperature on mortality in Madrid for people older than 65, using ARIMA and GAM models. Data correspond to 1,815 winter days over the period 1986-1997, during which time a total of 133,000 deaths occurred. The daily maximum temperature (T(max)) was shown to be the best thermal indicator of the impact of climate on mortality. When total mortality was considered, the maximum impact occurred 7-8 days after a temperature extreme; for circulatory diseases the lag was between 7 and 14 days. When respiratory causes were considered, two mortality peaks were evident at 4-5 and 11 days. When the impact of winter extreme temperatures was compared with that associated with summer extremes, it was found to occur over a longer term, and appeared to be more indirect.

Aged↗
PubMed2004

What is the value of social values? The uselessness of assessing health-related quality of life through preference measures.

BACKGROUND: The use of preference-based measures in the evaluation of health outcomes has extended considerably over the last decade. Their alleged advantage over other types of general instruments in the evaluation of health related quality of life (HRQOL), supposedly lies in the fact that preference measures incorporate values or utilities that reflects the value of social preferences through health states. The objective of this study was to determine whether the use of social preference weights or utilities makes any real difference when calculating scores for the Euroqol (EQ5-D) questionnaire, a HRQOL preference-based measure. METHODS: Responses to the EQ5-D of a sample of 10,972 patients from 10 countries enrolled in an observational study of the treatment of schizophrenia in Europe were used for this purpose. Two different methods of scoring the EQ-5D where compared: 'weighting the items' of the questionnaire through the UK official weight coefficients, and 'non-weighting the items'. Pearson's, Spearman's, and two-way mixed parametric intraclass correlation coefficients were used to estimate the association of the scores obtained in both ways. RESULTS: The association between weighted and unweighted Euroqol scores was extremely high (Pearson's r = 0.91), as was the association between their ranks (Spearman's rho = 0.93). The intraclass correlation coefficient obtained (0.89) also suggested that the concordance between the score distributions was prominent. CONCLUSIONS: A non-weighted approach to score the EQ5-D is enough to explain a high proportion of variance in scores obtained through the use of utilities. The differential contribution of weights based on population preference values is therefore minimal and, in our opinion, negligible.

Data Interpretation, Statistical↗
PubMed2004

Acromegaly Quality of Life Questionnaire (AcroQoL).

Acromegaly is a chronic disease with an important impact on patients, Health Related Quality of Life (HRQoL). The ability to effectively measure Health Related Quality of Life is central to describing the impacts of disease or treatment upon the patient, therefore the importance of having a disease specific questionnaire for acromegaly. For the development of the AcroQoL questionnaire different sources of information were used: first a literature search was performed to identify relevant papers describing the impact of acromegaly in HRQoL, second the main domains of impact on HRQoL were identified by 10 experts endocrinologists, and third ten in-depth semi-structured interviews were conducted in acromegalic patients to identify domains and items related to the self-perceived impact of acromegaly in patients' life. After a proper qualitative analysis a preliminary 38 item questionnaire was obtained. Rasch analysis concluded with a final 22 item questionnaire. The measurement properties (validity and reliability) of the resulting final questionnaire were tested and compared using standard procedures (Cronbach's Alpha and item-total correlation). The evaluation of the item parameters confirmed the construct validity of the new instrument. Responsiveness to change was assessed in a small sample of 32 acromegalic patients with active disease in Spain who were administered the AcroQoL and the generic questionnaire EuroQoL 5-D. The results showed a statistically significant relationship between all the dimensions of AcroQoL and the VAS (visual analogic scale) of EQ-5D. An improvement in the global score of AcroQoL was related to a global improvement in the VAS of the EQ-5D. Following the current recommended standard methodology the Spanish questionnaire was translated into eleven other languages.

Acromegaly↗
PubMed2004

Secular decreasing trend of the frequency of hypospadias among newborn male infants in Spain.

BACKGROUND: The frequency of hypospadias is not uniform worldwide. Several countries have reported an increase in its frequency at birth. Although a better ascertainment of the minor forms has been considered as an explanation, the potential effect of environmental endocrine disrupters has also been proposed. We studied the secular trend of hypospadias in Spain over the past 22 years, separating the minor and major forms. METHODS: We used data from the Spanish Collaborative Study of Congenital Malformations (ECEMC) registry, analyzing the frequency in two different periods: from 1978 to 1995, and from 1996 to 2002. To evaluate the "step" of the frequency between the two periods, we applied a parametric Student's t-test, and the nonparametric Mann-Whitney rank test. RESULTS: The birth frequency of isolated and total hypospadias was quite stable between 1978 and 1995. In 1996, it decreased dramatically in a step, essentially due to isolated cases with minor forms of hypospadias. Study of the geographical distribution by the 17 Spanish regions showed that the frequency step occurred in nearly all of them. CONCLUSIONS: It is difficult to consider that the observed decrease of the frequency of minor forms of hypospadias could be due to less accurate reporting of these minor forms in all 87 hospitals in the same year without any previous physician agreement. This decrease rather suggests a change in some product or exposure affecting the whole country. We think that the observed change in the frequency cannot be attributable to a lower exposure to endocrine disrupters or the voluntary interruption of gestation.

Geography↗