BACKGROUND: Hand osteoarthritis is a prevalent joint condition that has a high burden of disease and an unmet medical need for effective therapeutic options. Since local inflammation is recognised as contributing to osteoarthritic complaints, the Hand Osteoarthritis Prednisolone Efficacy (HOPE) study aimed to investigate the efficacy and safety of short-term prednisolone in patients with painful hand osteoarthritis and synovial inflammation. METHODS: The HOPE study is a double-blind, randomised, placebo-controlled trial. We recruited eligible adults from rheumatology outpatient clinics at two sites in the Netherlands. Patients were considered eligible if they had symptomatic hand osteoarthritis and signs of inflammation in their distal and proximal interphalangeal (DIP/PIP) joints. For inclusion, patients were required to have four or more DIP/PIP joints with osteoarthritic nodes; at least one DIP/PIP joint with soft swelling or erythema; at least one DIP/PIP joint with a positive power Doppler signal or synovial thickening of at least grade 2 on ultrasound; and finger pain of at least 30 mm on a 100-mm visual analogue scale (VAS) that flared up during a 48-h non-steroidal anti-inflammatory drug (NSAID) washout (defined as worsening of finger pain by at least 20 mm on the VAS). Eligible patients were randomly assigned (1:1) to receive 10 mg prednisolone or placebo orally once daily for 6 weeks, followed by a 2-week tapering scheme, and a 6-week follow-up without study medication. The patients and study team were masked to treatment assignment. The primary endpoint was finger pain, assessed on a VAS, at 6 weeks in participants who had been randomly assigned to groups and attended the baseline visit. This study is registered with the Netherlands Trial Registry, number NTR5263. FINDINGS: We screened patients for enrolment between Dec 3, 2015, and May 31, 2018. Patients completed baseline visits and started treatment between Dec 14, 2015, and July 2, 2018, and the last study visit of the last patient was Oct 4, 2018. Of 149 patients assessed for eligibility, 57 (38%) patients were excluded (predominantly because they did not meet one or several inclusion criteria, most often because of an absence of synovial inflammation or of flare-ups after NSAID washout) and 92 (62%) patients were eligible for inclusion. We randomly assigned 46 (50%) patients to receive prednisolone and 46 (50%) patients to receive placebo, all of whom were included in the modified intention-to-treat analysis of the primary endpoint. 42 (91%) patients in the prednisolone group and 42 (91%) in the placebo group completed the 14-week study. The mean change between baseline and week 6 on VAS-reported finger pain was -21·5 (SD 21·7) in the prednisolone group and -5·2 (24·3) in the placebo group, with a mean between-group difference (of prednisolone vs placebo) of -16·5 (95% CI -26·1 to -6·9; p=0·0007). The number of non-serious adverse events was similar between the groups. Five serious adverse events were reported during our study: one serious adverse event in the prednisolone group (a myocardial infarction) and four serious adverse events in the placebo group (an infected traumatic leg haematoma that required surgery, bowel surgery, atrial fibrillation that required a pacemaker implantation, and symptomatic uterine myomas that required a hysterectomy). Four (4%) patients discontinued the study because of an adverse event: one (2%) patient receiving prednisolone (for a myocardial infarction) and three (7%) patients receiving placebo (for surgery of the bowel and for an infected leg haematoma and for Lyme disease arthritis of the knee). INTERPRETATION: Treatment with 10 mg prednisolone for 6 weeks is efficacious and safe for the treatment of patients with painful hand osteoarthritis and signs of inflammation. The results of our study provide clinicians with a new short-term treatment option for patients with hand osteoarthritis who report a flare-up of their disease. FUNDING: Dutch Arthritis Society.