EURURO Vol. 72 No. 4

540 656

biopsy is not negligible . Apart from the costs related to
adverse events, there is also a potential cost linked to
imaging . A change from AS to WWmay thus reduce
health care expenditure as there will be fewer follow-up
costs (eg, biopsies and related complications, imaging). Data
on the change from AS to WW will not only help in
estimating these costs, but also affect the validity of current
health evaluations of AS effectiveness, as patients need
information on the change from AS to WW to provide
accurate patient-reported outcome measures and experi-
ence measures for AS
A major strength of our study is the use of comprehen-
sive data from PCBaSeTraject, a large, nationwide, popula-
tion-based database on PCa . These data were used to
assess transition rates in the models for the changes
between different treatment options. Owing to the detailed
information available, we could adjust our estimations for
comorbidities and age, resulting in high internal validity.
The models are therefore reliable. Even though our results
were based on Swedish data only, we believe that the
external validity of our study is acceptable for other
populations with similar age-related rates of change in
CCI. A limitation of our study is the scarce data on follow-up
(eg, on repeat biopsies) as these are underreported in the
Patient Register, and lack of information on the actual
change from AS to WW for individual patients. Another
limitation is that follow-up was not long enough to
investigate causes of death for men with low-risk PCa on
AS. With longer follow-up, a future study including this
information could provide insight into whether AS was an
appropriate choice and whether the change to WW was
performed at the right time. Finally, it may be a limitation
that we assumed similar transition rates for WW to ADT and
AS to ADT for men of all ages, an assumption that cannot be
verified by our data. However, we evaluated the effects of
this assumption using different rates and noted very little
differences in the results.
5. Conclusions
We estimated that changes from AS to WW become
more common in men with very low-risk PCa, especially
those who were elderly at the time of AS initiation. Our state
transition models estimated that a large proportion of
men with very low-risk PCa starting AS will change to
WW. These observations suggest that patients need to be
informed about this potential change before starting AS.
Moreover, the impact of the change to WW on allocation of
health care resources has probably been underestimated to
date (less follow-up expenditure on WW compared to AS)
and future guidelines on follow-up during AS should take
this into account.
Author contributions: Mieke Van Hemelrijck had full access to all the data in
the study and takes responsibility for the integrity of the data and the
accuracy of the data analysis.
Study concept and design: Adolfsson, Van Hemelrijck, Lindhagen, Garmo.
Acquisition of data: Stattin, Garmo.
Analysis and interpretation of data: Van Hemelrijck, Garmo, Lindhagen.
Drafting of the manuscript: Van Hemelrijck.
Critical revision of the manuscript for important intellectual content:
Lindhagen, Garmo, Adolfsson, Stattin, Bratt.
Statistical analysis: Garmo, Lindhagen.
Obtaining funding: Stattin, Adolfsson.
Administrative, technical, or material support: Stattin.
Supervision: Van Hemelrijck, Adolfsson.
Other: None.
Financial disclosures: Mieke Van Hemelrijck certifies that all conflicts of
interest, including specific financial interests and relationships and
affiliations relevant to the subject matter or materials discussed in the
manuscript (eg, employment/affiliation, grants or funding, consultan-
cies, honoraria, stock ownership or options, expert testimony, royalties,
or patents filed, received, or pending), are the following: None.
Funding/Support and role of the sponsor:This work was supported by the
Swedish Research Council for Working Life, Health, and Welfare (825-
2012-5047), the Swedish Cancer Society (14- 0570), the Cancer Society
of Stockholm, and Uppsala County Council. The sponsors played no
direct role in the study.
Acknowledgments: This project was made possible by the continuous
work of the National PCa Register of Sweden (NPCR) steering group: Pa¨r
Stattin (chairman), Anders Widmark, Camilla Thellenberg Karlsson, Ove
Andre´n, Anna Bill-Axelson, Ann-Sofi Fransson, Magnus To¨rnblom, Stefan
Carlsson, Marie Hja¨lm Eriksson, David Robinson, Mats Ande´n, Jonas
Hugosson, Ingela Franck Lissbrant, Maria Nyberg, Go¨ran Ahlgren, Rene´
Blom, Lars Egevad, Calle Waller, Olof Akre, Per Fransson, Eva Johansson,
Fredrik Sandin, and Karin Hellstro¨m.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at
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