Urinary system stone treatment management varies according to the
characteristics of the stone and patient preference and physician
experience. Treatment options include medical therapy, extracorporeal
shock wave treatment (ESWL), percutaneous nephrolithotomy (PCNL), and
ureterorenoscopy (URS).1 In addition to PCNL being
recommended for stones of >2 cm in size, with the recent
developments in the device and laser technologies and increase in
surgeon experience, flexible URS (fURS) is also reported to result in
satisfactory stone-free rates (SFRs) in these
stones.2,3 Xu et al. reported that effective treatment
could be applied even in stones with a cumulative burden of
>4 cm.4 The usage area and popularity of
fURS is increasing day by day.5 With the widespread
use of fURS in large renal stones, the choice of treatment will become
more and more difficult.
Many scoring systems have been developed to predict the success of ESWL,
URS, and PCNL in urinary system stones.6–9 It has
been proven that stone-free status (SFS) and development of
complications can be effectively predicted with scoring systems,
especially in PCNL.10 In the literature, several
scoring systems, including Resorlu-Unsal11,
STONE12, S-ReSC13, and
R.I.R.S.14 and one nomogram15 have
been defined to predict the success of fURS. Among these scoring
systems, only STONE score is used for kidney and ureter stones. The
STONE scoring system consists of the parameters of (S)ize, (T)opography
(stone localization), (O)bstruction, (N)umber of stones, and
(E)valuation of stone density (Hounsfield unit, HU). Although the
developing authors reported high predictive values for this system,
their patient data belong to 2006-2012.12 Considering
that the STONE scoring system would not preserve its predictive value in
the face of developing technology, Hori et al. developed a practical
scoring system comprising the (T)allness, (O)ccupied lesion,
(HO)unsfield unit components and named it T.O.HO.16 In
the current study, we aimed to evaluate factors associated with SFS in
patients treated with fURS for ureteral and kidney stones and perform
the external validation of the T.O.HO. and STONE score. We also aimed to
derive a modified version of the T.O.HO. score and perform the internal
validation of this version.