The effect of vitamin D supplementation on vitaminD levels in patients with severe mental illness - a prospective trial

For various reasons, it is important to achieve and maintain appropriate
vitamin D levels.Therefore different guidelines advise to treat patients who
are at risk for vitamin D deficiency. Although the literature shows that
patients with severe mental illness (patients with SMI) also have a higher risk
of vitamin D deficiency, this category of patients is not yet included in the
risk groups. Furthermore, there is no research in this group of patients on the
effective dose of vitamin D to achieve adequate vitamin D levels.

The main objective of this study is to investigate if 800 IU or 1600 IU vitamin
D is needed to reach adequate levels of vitamin D after 3 months of treatment
in at least 80% of the patients with severe mental illness (patients with SMI)
between 18 and 70 years (women up to 50 years) and a vitamin D deficiency?

Secondary objectives of the study are:
- Is it cost effective to determine vitamin D levels in all patients with SMI
and to treat only those with a vitamin D deficiency or could the treatment be
given to all patients with SMI independent of the vitamin D level, for a period
of 1 year?
- Is it cost effective to determine vitamin D levels in all patients with SMI
and to treat only those with a vitamin D deficiency or could the treatment be
given to all patients with SMI independent of the vitamin D level, for a period
of 5 years?
- Does the patients psychiatric disease, age, gender, body mass index or
smoking status significantly influence the required amount of vitamin D?
- What is the average increase in vitamin D levels in patients with SMI per
100 IU cholecalciferol with a daily oral intake?

The vitamin D levels of all participants in the study will be measured at
baseline. Those with inadequate levels (i.e. <50nmol /L) receive a daily oral
dose of 800 IU cholecalciferol. The treatment group will get a new vitamin D
measurement after 3 months. When the level is still inadequate, the dosage will
be further increased to 1600 IU per day. After another 3 months, there will be
one last measurement to determine if an adequate level has been reached.

Daily intake of 800 IU cholecalciferol in all patients with inadequate vitamin
D levels for 3 months. The dose will be increased to 1600 IU daily for another
3 months if the level is still inadequate after 3 months of treatment with 800
IU daily.

The potential risk to the participating patients will be very
low.Cholecalciferol is registered for the treatment and prevention of a vitamin
D deficiency and has in the applied therapeutic doses (800 IU and 1600 IU)
almost no side effects. Very rare side effects are pruritus, rash, and
urticaria. It is not likely that the dosage will lead to a toxic level in
proper use or other adverse effects. Only those patients with a vitamin D
deficiency are treated.
In addition, the number of venipunctures will be limited to a minimum (maximum
of 3 venipunctures from 5 ml). The ones that are necessary will be performed
simultaneously with another venipuncture where possible, so that the additional
burden on patients is limited.