[Show abstract][Hide abstract] ABSTRACT: Considering the significant morbidity and mortality of pulmonary arterial hypertension (PAH) in patients with systemic sclerosis (SSc) and the lack of precise information on disease in Latin America, we investigated the clinical and laboratory characteristics associated with PAH in Colombian patients with SSc and review the literature.
This multicenter study included patients followed at 5 rheumatology units that were systematically assessed using a pretested questionnaire on clinical and immunological variables, focusing on PAH. Conditional logistic regression was employed to assess association between PAH and specific clinical characteristics. A systematic review of the literature was performed through electronic databases.
Of a total of 349 patients with SSc, 61 (17%) met the criteria for PAH. Pulmonary fibrosis [adjusted odds ratio (AOR) 7.37, 95% CI 3.67-14.81, p < 0.0001], microstomia (AOR 3.3, 95% CI 1.70-6.28, p < 0.0001), gastroesophageal reflux (AOR 2.41, 95% CI 1.31-4.43, p = 0.005), dysphagia (AOR 2.7, 95% CI 1.49-4.77, p = 0.001), hyperpigmentation (AOR 2.15, 95% CI 1.11-4.16, p = 0.02), and hypopigmentation (AOR 2.4, 95% CI 1.26-4.64, p = 0.008) were the most prevalent clinical characteristics associated with PAH, while anemia (AOR 5.4, 95% CI 1.98-14.93, p = 0.001) was observed as the unique laboratory risk factor. Association between subtypes of SSc and PAH was not observed. Significant differences in both clinical and laboratory data were observed among different series.
PAH may be a frequent complication of SSc in the Colombian population regardless of disease subtype. The identified clinical and laboratory risk factors might assist earlier diagnosis and guide decisions on therapeutic interventions on this critical complication of SSc. The reasons underlying the reported divergences among patients from different ethnicities are not fully understood, but it is most likely that both genetic and environmental factors are responsible for them.
Full-text · Article · Feb 2008 · The Journal of Rheumatology
[Show abstract][Hide abstract] ABSTRACT: We consider a three state model with an absorbing state assuming an underlying Markov process to explain the dependence among observations within subjects. We compare, using a simulation study, three different parameterizations of the transition intensity rate: the first one is based on the Andersen-Gill's multiplicative hazard model (Andersen et al. 1993), the second one is based on the logistic model, and the third one depends on the complementary log-log model. The method to estimate the effect of the parameters is based on the likelihood function which can be optimized using the exact solutions of a Kolmogorov forward differential equations system in conjunction with the Newton-Raphson algorithm (Abramowitz & Stegun 1972). We use the relative bias to select the best estimation estrategy. The methodology is ilustrated using longitudinal data about rheumatoid arthritis (RA) from the Corporación para Investigaciones Biológicas, CIB.
Full-text · Article · Dec 2007 · Revista Colombiana de Estadistica