Back supports can help to protect injuries to the lower back, by augmenting the function of the stabilising muscles and helping to prevent painful, secondary spasms.
Unfortunately, back supports do nothing to alleviate the primary condition and are not suitable for the treatment of chronic back pain which is, by definition, long term. Prolonged use will lead to muscular atrophy, a disorder characterised by weak muscles; in turn, this can leave the back susceptible to further injury.
Back supports might be of some use in acute, short-term cases. They should not be worn for any protracted length of time. They do not treat the causes of back pain.