Let $p$ be the probability of any event in repeated independent trials. Sequential tests of the composite hypothesis $p \leqq p_0$ against the composite hypothesis $p > p_0$ are proposed, which asymptotically minimize the maximum risk when the cost of experimentation tends to zero, if the loss depends only on $p$ and satisfies some natural regularity conditions. Asymptotic power, expected sample size and risk of the tests are also given.
"The Asymptotic Minimax Character of Sequential Binomial and Sign Tests." Ann. Statist. 1 (6) 1139 - 1148, November, 1973. https://doi.org/10.1214/aos/1176342562