Guttate psoriasis (GP) typically occurs abruptly following an acute infection such as streptococcal pharyngitis. It is thought to have a good prognosis and show rapid resolution; however, there are limited studies addressing long-term outcomes of GP, particularly the probability of developing chronic plaque psoriasis (PP) following a single episode of acute GP.
Ko et al1 reported a long-term follow-up study of Korean patients with acute GP. The investigators determined that 19 of 36 participants (38.9%) with acute GP went on to develop chronic PP over a mean follow-up period of 6.3 years. Martin et al2 reported a smaller follow-up study of 15 patients in England; 5 of 15 patients (33.3%) developed chronic PP within 10 years.
A retrospective cohort study was performed using data from the Geisinger Medical Center (Danville, Pennsylvania) electronic medical records from January 2000 to September 2012 to identify medical records that showed a specific clinical diagnosis of GP or a diagnosis of either dermatitis or psoriasis with a positive molecular probe for streptococci or antistreptolysin O (ASO) titer. (A molecular probe is used in place of culture for streptococcal pharyngeal specimens at our institution.) A separate search of the Co-Path database for biopsy-proven GP also was performed. Each medical record was reviewed by one of the authors (L.F.P.) to confirm the true diagnosis of GP. Exclusion criteria included a prior diagnosis of PP or a follow-up period of less than 1 year. Based on this chart review, the prevalence of developing chronic PP in patients with GP was determined. The patients were split into 2 cohorts: those who had a single episode of GP with resolution versus those who developed PP. We compared the clinical characteristics to those who developed chronic PP. The clinical characteristics that were recorded included patient age; whether or not the patient developed PP; length of time for clearance of GP; molecular probe or ASO results; family history; GP treatment used; smoking status; and comorbid conditions such as hyperlipidemia, hypertension, diabete mellitus, and obesity, which were lumped under the category of metabolic syndrome due to their low prevalence individually.
The study group data set contained 79 patients with GP who had a history of at least 1 year of follow-up. Descriptive statistics of the patients were provided for continuous and categorical variables in the study. Continuous variables were described using the mean and SD or, for skewed distributions, the median and interquartile range (25th-75th percentiles), while categorical variables were presented using frequency counts and percentages. Comparisons between groups were tested using 2-sample t tests or Wilcoxon rank sum tests, or Pearson χ2 or Fisher exact tests, as appropriate.
A total of 79 patients were included in the study. Descriptive statistics for the total patient population as well as those who did and did not develop PP are shown in Table 1. The median age of patients was 37 years. The median follow-up time was 5 years. The majority of patients were female (68.4%). There were 20 patients (25.3%) who developed PP and 59 (74.7%) who did not (95% CI, 0.1-0.36).
Molecular probes for streptoccoci were obtained from 31 patients (39.2%) during the workup for GP. Patients who had a molecular probe and developed PP were less likely to have had a molecular probe that was positive for streptococci versus patients who did not develop PP (0% vs 61.5%; P=.0177)(Table 2). Patients who developed PP were more likely to have persistent GP at 12 months than patients who did not develop PP (26.3% vs 6.8%, respectively; P=.0414). At the end of the observation period, 4 patients (5.1%) did not yet show GP clearance. The patients who developed PP were more likely to have had a case of GP that never cleared than patients who did not develop PP (15.8% vs 1.7%; P=.0505)(Table 3).
No significant differences were detected among those who developed PP compared to those who did not with respect to any degree of family history of psoriasis (22.2% vs 26.4%; P=1.0000)(Table 4). There were no significant differences in the value of a positive ASO titer between groups (Table 2), but it should be noted that the small number of patients with positive values in each group impacts a test’s power to detect statistically significant differences. There were no significant differences in the likelihood of developing PP if a patient was treated with systemic steroids or antibiotics (data not shown). Additionally, smoking status, hyperlipidemia, hypertension, diabetes mellitus, and obesity were not predictive of evolution of GP into PP (data not shown).