Subclinical rejection and borderline changes in early protocol biopsy specimens after renal transplantation

Background. To determine the significance of early subclinical rejection, we reviewed protocol biopsies performed on days 7 and 28 during a 4-year period. Methods. The study was confined to patients (n = 115) with stable graft function at the time of biopsy; 76 adequate biopsies at day 7 and 79 at day 28 were performed. Results. At day 7, 10 biopsy specimens (13%) showed acute rejection (AR) and 9 (12%) showed borderline changes. Eight of 10 patients with AR received immediate pulsed methylprednisolone (MP) and one untreated patient developed clinical rejection (CR) within 3 days. Four of nine patients whose biopsy specimens showed borderline changes received MP and three untreated patients developed CR within 3 days. At day 28, six biopsy specimens (8%) showed AR and 13 (16%) showed borderline changes. Three of six patients with AR received immediate pulsed MP and one untreated patient developed CR within 6 days. Ten of 13 patients with borderline changes had been treated for AR in the previous 3 weeks. Twelve patients with subclinical rejection or borderline changes at day 28 were never subsequently treated for rejection, and outcome at 6 years did not differ from those patients whose biopsy specimens showed no rejection. Conclusions. Compared with some units, the incidence of subclinical rejection is low. The majority of untreated subclinical borderline changes and rejection at day 7 behaved as early clinical rejections and at day 28 as resolving clinical rejections. Untreated subclinical rejection or borderline change at day 28 was not an adverse prognostic factor for long-term outcome.