Steroid therapy and outcome of parapneumonic pleural effusions (STOPPE): study protocol for a multicenter, double-blinded, placebo-controlled randomized clinical trial by Fitzgerald, D, Waterer, G, Read, C, Fysh, E, Shrestha, R, Stanley, C, Muruganandan, S, Lan, N, Popowicz, N, Peddle-Mcintyre, C, Rahman, N, Gan, S, Murray, K, Lee, Y