Socioeconomic inequality, waiting time initiatives and austerity in Scotland: an interrupted time series analysis of elective hip and knee replacements and arthroscopies.

Objectives: National Health Service (NHS) waiting times have long been a political priority in Scotland. In 2002, the Scottish government launched a programme of investment and reform to reduce waiting times. The effect on waiting time inequality is unknown as is the impact of subsequent austerity measures.

Design: An interrupted time series analysis between the most and least socioeconomically deprived population quintiles since the introduction of waiting time initiative 1 July 2002 and austerity measures 1 April 2010.

Setting: All NHS-funded elective primary hip replacement, primary knee replacement and arthroscopy patient data in Scotland from 1 April 1997 to 31 March 2019.

Participants: NHS Scotland funded patients treated in Scotland.

Main Outcome Measures: Trends and changes in mean waiting time.

Results: There were 135,176, 122,883 and 173,976 NHS funded hip replacement, knee replacement and arthroscopy patients, respectively, in Scotland between 1 April 1997 and 31 March 2019. From 1 July 2002 to 31 March 2010, waiting time inequality between the most and least deprived patients fell and increased thereafter. For hip replacements before 1 July 2002, waiting time inequality increased 1.07 days per quarter; this changed at 1 July 2002 with significant slope change of -2.32 (-3.53, -1.12) days resulting in a decreasing rate of inequality of -1.26 days per quarter. On 1 April 2010 the slope changed significantly by 1.84 (0.90, 2.78) days restoring increasing inequality at 0.58 days per quarter. Knee replacements and arthroscopies had similar results.

Conclusions: The waiting time initiative in Scotland is associated with a reduction in waiting time inequality benefiting the most socioeconomically deprived patients. Austerity measures may be reversing these gains.