Aurelio Tobías

Quality of life of caregivers in Parkinson’s disease

Objective: To assess the impact of PD on informal caregivers of patients and identify the main factors related to caregiver strain. Patients and methods: Pairs of PD patients and their caregivers. Evaluation by neurologists included the Hoehn and Yahr, Schwab and England, UPDRS (parts 1–3), ISAPD, and Pfeiffer’s SPMSQ rating scales. Patients completed the Euro-QoL 5D, PDQ-8, and Hospital Anxiety and Depression Scale. The SQLC was used to assess caregivers’ quality of life (QoL), with caregivers, in turn, applying the Euro-QoL and PDQ-8 to assess patients’ health-related quality of life (HRQoL). Multiple linear regression models were fitted to ascertain factors linked to the SQLC. Results: Significant correlations were in evidence between the following scores: SQLC and clinical rating scales and SQLC and patients’ HRQoL. Based on multiple regression analysis, patients’ functional state (ADL) proved to be the main predictor of caregivers’ QoL. Self- and caregiver-assessed patients’ HRQoL also proved to be a relevant factor. Conclusions: (1) Patients’ functional state was significantly related to caregivers’ psychosocial burden; (2) patients’ HRQoL proved to be an additional factor linked to caregiver QoL; (3) improvement of patient disability and HRQoL might alleviate caregiver strain.

Parkinson's Disease Sleep Scale: validation study of a Spanish version.

The Parkinsons Disease Sleep Scale (PDSS) is the first published bedside clinical tool to specifically measure sleep disturbances in Parkinsons disease (PD). The objective of the present study was to carry out a metric analysis of a Spanish version (PDSS‐SV) using a cross‐sectional study of 100 PD patients who participated in the study. Usual measures for PD and mental status were applied by neurologists. Patients completed the Epworth Sleepiness Scale, Parkinsons Disease Questionnaire‐39 Items (PDQ‐39), and PDSS‐SV. PDSS internal consistency (Cronbachs α, 0.77; significant item‐total correlation for 11 items) was satisfactory. PDSS showed high test–retest reliability (intraclass correlation coefficient for items, 0.79–0.99; for total score, 0.94). Standard error of measurement was 9.80 (crossover) and 5.01 (longitudinal). Scores were distributed uniformly, with low floor and ceiling effect (1%). PDSS scores were correlated significantly with depression (Hamilton Depression Rating Scale, rS = −0.55; P < 0.0001) and quality of life (PDQ‐39 Summary Index, rS = −0.26; P = 0.007), but not with clinical variables. Self‐perception of mood disorder, pain, or hallucinations correlated individually with PDSS scores, and a factor explaining 65% of the variance was found. The assessment of PD sleep disorders with the PDSS met some basic standards required for health status measures.

Public health surveillance and incidence of adulthood Guillain-Barré syndrome in Spain, 1998–1999: the view from a sentinel network of neurologists

Abstract.Temporal variation in Guillain-Barré syndrome (GBS) warrants monitoring in certain situations. This study sought to describe a public-health-based GBS surveillance service in Spain and conduct pilot surveillance in the period 1998-1999. Neurologists from 11 hospitals countrywide, serving a population of 3.9 million, reported all patients, ages 20 years or over, admitted to hospital with suspected GBS. Cases that did not belong to the designated hospital catchment area or failed to fulfill diagnostic criteria after follow- up were excluded. Reported monthly incidence was compared against predicted incidence obtained from retrospective data (1985–1997) using a reported method based on 97.5% percentile values. Alarm thresholds for 2000 onwards were obtained by applying the same method to the updated 1985–1999 series. During the 2-year period, 98 GBS cases were reported, yielding an overall age-adjusted incidence of 1.26 per 100 000 population, with a breakdown by sex of 1.83 for males and 0.76 for females. Monthly incidence remained below or was similar to the corresponding threshold limit value. Seasonality with highest incidence in winter was more pronounced in the elderly. Preceding events, mainly respiratory infections, were identified in 71% of patients. Pilot two-year GBS surveillance in Spain resulted neither in alarm nor in preventive measures. Adult GBS incidence in Spain might be monitored by a surveillance system set up at short notice when a possible threat is perceived. A monthly incidence of over 3 per 100 000 person-years in the population aged 20 years or older would exceed threshold values.

Guillain-Barré Syndrome in Spain, 1985–1997: Epidemiological and Public Health Views

Retrospective demographic information and hospital record data were collected for 337 patients resident in Spain who had validated Guillain-Barré syndrome (GBS) diagnoses and clinical onset during the period 1985–1997 and had been admitted to 11 centres, covering a population of 3.9 million. The European age-adjusted GBS incidence per 100,000 for 1985–1997 among the population aged 20 and over was 0.85, with a breakdown of 1.14 in men and 0.58 in women. Incidence increased with age and time, with occasional rises that mimicked outbreaks and occurred at irregular 2- to 4-year intervals, mainly in winter. Spatial variation was modest. Respiratory and gastrointestinal infections respectively constituted 49.3 and 19.3% of recorded preceding events. The 97.5% intercentile limit, obtained from the 1985–1997 monthly incidences using predictions from a Poisson model, was proposed as the threshold value for pilot epidemiological surveillance of GBS in 1998–1999.

Are the limit values proposed by the new European Directive 2008/50 for PM2.5 safe for health?

Directive 2008/50 CE of the European Parliament and Council of 21 May 2008 on ambient air quality and cleaner air for Europe was recently approved.1 Annex XIV of the Directive establishes two stages for particulate matter having a diameter of under 2.5 micron (PM2.5). Stage 1 indicates that the calendar year limit value for this pollutant is to be 25 μg/m3 and that the date by which the limit value is to be attained is 1 January 2015. In Stage 2, the calendar year limit value is set at 20 μg/m3 and is to be attained by 1 January 2020, though the Directive itself indicates that these indicative limit values will be reviewed by the Commission in 2013 in the light of further information on health and environmental effects, technical feasibility and experience of the target value (25 μg/m3 at 1 January 2010) in Member States. It is evident that PM2.5 emission levels equal to zero are impossible to achieve in large cities, and that there must be a balance between desirable levels of protection of human health and feasible emission levels. Nevertheless, …

Point-wise estimation of non-linear effects of airborne pollen levels on asthma emergency room admissions.

Airborne pollen levels have been associated with an increase in asthma morbidity (1). This relationship has usually been formulated in terms of a linear form. However, effects of environmental exposures on health could also be nonlinear (2). Approximations based on linear modals present limitations making arbitrary assumptions about shape of the relationship; also, categorical analyses usually have low efficiency and cut-off points are in most cases opportunistic (3). To solve these limitations, a nonparametric method to compute point-wise estimation of non-linear exposures has recently been proposed (4). Under a Generalized Additive Model (GAM) a nonparametric estimate of the relative risk (RR) can be defined as RRðx; xrefÞ 1⁄4 exp f ðxÞ f ðxrefÞ ð Þ, where xref is the reference value of the continuous exposure and f(x) any of usual smoothers. Asymptotic variance of ln(RR(x,xref)) can be expressed in terms of the covariance matrix of the smoother f(x) as

Case-crossover design: Basic essentials and applications

Abstract Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subjects exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design.

Application of the chi-plot to assess for dependence in environmental epidemiology studies

Several studies have illustrated the short-term effects of environmental factors such as air pollution on health, using a wide range of time-series regression models. However, there have been few reports of descriptive analyses based on data visualization, which can be used for a preliminary inspection of relationships between health outcomes and exposure factors. The commonly used scatterplot, displaying a large number of points, cannot adequately assess complex bivariate dependence structures. This paper presents a graphical display, the chi-plot, which, used jointly with the scatterplot, provides a powerful tool to describe a varied range of bivariate dependence structures in environmental epidemiology studies. We studied the relationship between emergency room admissions for asthma, air pollutants and pollen types in Madrid (Spain) during the period 1995–1998. Associations were depicted graphically using chi-plots and were consistent with those previously reported.

Parkinson's disease sleep scale: Validation study of a Spanish version: Validation Study

The Parkinsons Disease Sleep Scale (PDSS) is the first published bedside clinical tool to specifically measure sleep disturbances in Parkinsons disease (PD). The objective of the present study was to carry out a metric analysis of a Spanish version (PDSS‐SV) using a cross‐sectional study of 100 PD patients who participated in the study. Usual measures for PD and mental status were applied by neurologists. Patients completed the Epworth Sleepiness Scale, Parkinsons Disease Questionnaire‐39 Items (PDQ‐39), and PDSS‐SV. PDSS internal consistency (Cronbachs α, 0.77; significant item‐total correlation for 11 items) was satisfactory. PDSS showed high test–retest reliability (intraclass correlation coefficient for items, 0.79–0.99; for total score, 0.94). Standard error of measurement was 9.80 (crossover) and 5.01 (longitudinal). Scores were distributed uniformly, with low floor and ceiling effect (1%). PDSS scores were correlated significantly with depression (Hamilton Depression Rating Scale, rS = −0.55; P < 0.0001) and quality of life (PDQ‐39 Summary Index, rS = −0.26; P = 0.007), but not with clinical variables. Self‐perception of mood disorder, pain, or hallucinations correlated individually with PDSS scores, and a factor explaining 65% of the variance was found. The assessment of PD sleep disorders with the PDSS met some basic standards required for health status measures.

Parkinson's disease sleep scale

The Parkinsons Disease Sleep Scale (PDSS) is the first published bedside clinical tool to specifically measure sleep disturbances in Parkinsons disease (PD). The objective of the present study was to carry out a metric analysis of a Spanish version (PDSS‐SV) using a cross‐sectional study of 100 PD patients who participated in the study. Usual measures for PD and mental status were applied by neurologists. Patients completed the Epworth Sleepiness Scale, Parkinsons Disease Questionnaire‐39 Items (PDQ‐39), and PDSS‐SV. PDSS internal consistency (Cronbachs α, 0.77; significant item‐total correlation for 11 items) was satisfactory. PDSS showed high test–retest reliability (intraclass correlation coefficient for items, 0.79–0.99; for total score, 0.94). Standard error of measurement was 9.80 (crossover) and 5.01 (longitudinal). Scores were distributed uniformly, with low floor and ceiling effect (1%). PDSS scores were correlated significantly with depression (Hamilton Depression Rating Scale, rS = −0.55; P < 0.0001) and quality of life (PDQ‐39 Summary Index, rS = −0.26; P = 0.007), but not with clinical variables. Self‐perception of mood disorder, pain, or hallucinations correlated individually with PDSS scores, and a factor explaining 65% of the variance was found. The assessment of PD sleep disorders with the PDSS met some basic standards required for health status measures.