We focused on the prediction of significant GI involvement in the early phase of HSP, and found that our scoring system, consisting of generally available laboratory parameters, may be of value. A score of 4 points or higher, at the time of admission showed a good predictive value for gross blood in stools, and was associated with a longer duration of abdominal pain under PSL treatment. Based on its considerable predictive value for severe GI involvement, our scoring system has the potential to determine whether PSL intervention or supportive therapy, such as temporal fasting, should be undertaken. Further, as the monitoring of scores by repeat evaluation in several patients showed sequential changes parallel with GI symptoms (data not shown), it may also be useful for clinical follow up.
The precise mechanism underlying the changes in the parameters comprising the scoring system has not yet been clarified. Kawasaki disease, another systemic vasculitis common in children, often presents as hyponatremia and hypoalbuminemia, especially in severe cases (Fukunishi et al. 2000; Kobayashi et al. 2006). Further, patients with ulcerative colitis present with elevated D-dimer levels (Alkim et al. 2011; Zezos et al. 2009) and decreased fXIII activity (Lorenz et al. 1991), reflecting the inflammation of and injury to the intestinal mucosa. In consideration of these facts, our results might be regarded as reflecting severe vasculitis and the subsequent destruction of the small vessels, resulting in massive injury to the intestinal mucosa.
The efficacy of glucocorticoid therapy against the early symptoms of HSP remains controversial to a point. Several randomized controlled trials have reported that short-term PSL therapy (1.5 ~ 2 mg/kg/day) reduces the intensity of abdominal pain and arthralgia in early HSP (Ronkainen et al. 2006; Chartapisak et al. 2009; Rosenblum & Winter 1987). However, there have been several patient reports describing severe, persistent GI involvement despite appropriate PSL therapy (Saulsbury 1999; Taylor et al. 1971). As the proportion of patients with severe GI involvement is small, their refractoriness might be hidden behind the majority of benign cases. However, in terms of preventing HSPN, early identification and management of this small proportion of patients with severe GI involvement might be more important as, along with persistent purpura (Kaku et al. 1998; Sano et al. 2002; Rigante et al. 2005; Shin & Lee 2006; de Almeida et al. 2007), older age (Kaku et al. 1998; Sano et al. 2002; de Almeida et al. 2007), and decreased fXIII activity (Kaku et al. 1998; Sano et al. 2002), it is known to be an independent risk factor for HSPN (Kaku et al. 1998; Sano et al. 2002; Ronkainen et al. 2006; Shin & Lee 2006). As current PSL therapy in early HSP does not prevent subsequent HSPN (Ronkainen et al. 2006; Chartapisak et al. 2009; Rosenblum & Winter 1987; Huber et al. 2004), we propose the future evaluation of novel therapeutic strategies according to disease activity, and our scoring system might make an important contribution to this evaluation.
Of course, our study has several limitations. Our definition of GI group classifications was dependent on subjective symptoms and fecal examination; therefore, the classification criteria might require some improvement in terms of accuracy. Further, the proportion of patients with gross blood in stools was small. Last, our study was based on only a single cohort analysis. The survey of another cohort of HSP of HSP patients using our scoring system should help prove its validity. In addition, further large-scale or prospective studies are needed to overcome these limitations.