The epidemiology of sickness absence
: individual-level risk factors for fit note receipt in health records 2014-2017

Student thesis: Doctoral ThesisDoctor of Philosophy


Background: In the UK, a major achievement of the last few decades is the increase in life expectancy. However, with this increase in survival we have seen a major rise in the number of years lived with disability, and associated sickness absence. The rise in working age adults on long term sickness absence (LTSA) has attracted concern internationally. A particular focus in the UK has been on the rise in LTSA for mental health conditions, which have overtaken musculoskeletal disorders as the leading cause of sickness absence. In a 2008 report by Dame Carol Black, sickness certification using the ‘sick note’ was identified as a contributor to LTSA in the UK. The sick note was binary: workers could only be ‘sick’ or ‘not sick’. The fit note was introduced in 2010, almost 100 years after the introduction of the sick note, to improve the process of sickness certification, by introducing a third option: ‘maybe fit’ with work adjustments. ‘Maybe fit’ was to be recommended by GPs if work adjustments could support the worker to return to or remain in work. The fit note was designed as an early intervention, that would facilitate prompt access to treatment and adaptations at work, early in disease onset. Despite the introduction of this national-level public health intervention, there has been relatively little research into the fit note and its use in the general population.

Aims: Firstly, to review the literature on fit note receipt and highlight gaps in our knowledge about the fit note. Secondly, to create a health record linkage between a large primary care database and secondary mental healthcare database in south London. To examine this linked dataset to create new knowledge about the fit note, by describing, for the first time, fit note receipt in a large primary care population by single morbidity and multimorbidity. To explore the impact of ‘health condition at first fit note’ on the number of fit notes subsequently received. And lastly, to examine inequalities in access to mental healthcare in the year after receiving a first fit note for a mental health condition.

Methods: The study is based in the London Borough of Lambeth, home to a population of 327,582 people and characterised by high deprivation, considerable income inequality and a high proportion of the population (38%) born outside of the UK. The population is young and ethnically diverse, including large populations of people who identify as Black African, Black Caribbean and Black British, as well as South Americans and Portuguese. I analysed the records of working age adults (aged 16-60) registered in primary care in Lambeth over a 40-month period, from 1st January 2014 to 30th April 2017. Data was extracted from a primary care dataset, Lambeth DataNet, which contains electronic clinical records for all 45 general practices in the London Borough of Lambeth. Extracted variables included patient-level data on demographics, clinical diagnoses, referrals, consultations, prescriptions, laboratory tests, and public health initiatives, including the Quality and Outcomes Framework diagnostic data. Lambeth DataNet was linked with a secondary mental healthcare database in south London: Clinical Record Interactive Search (CRIS). The South London and Maudsley National Health Service Foundation Trust provides comprehensive mental healthcare for residents of Lambeth. CRIS has been further linked with the Improving Access to Psychological Treatment programme, which provides data on primary care psychological treatment for common mental disorders.

Results: (1) A systematic review revealed major gaps in the literature on fit note use. (2) Data linkage between Lambeth DataNet and CRIS was successful but took longer than expected. (3) In the first analysis, depression stood out as the long-term condition with the biggest impact on fit note receipt of all long-term conditions. The highest risk of fit note receipt was amongst older people, women, people in the Black Caribbean group and in areas of high deprivation. The same demographic groups were at highest risk of long-term conditions, but long-term conditions did not explain demographic variation in fit note receipt. Unmeasured confounding by individual-level deprivation (I was limited to area-level deprivation measures) and occupational characteristics (such as job type) could explain some of this variation. (4) In the second analysis, multimorbidity was strongly associated with fit note receipt. Depression stood out as the comorbid condition with the strongest association with fit note receipt. (5) In the third analysis, I found the small group with drug and/or alcohol misuse at first fit note had the highest number of fit notes of any health condition at first fit note. (6) In the final analysis, I found that people with mental health conditions, when recognised by the GP, usually do receive some form of mental health intervention following receipt of a fit note, although this varied by demographic factors. Having no mental health treatment indicator after first fit note for a mental health condition was most common in the Black African and Black Caribbean groups.

Conclusion: This thesis addresses major gaps in the literature on fit note use. I found a striking lack of evidence on the impact of the fit note given that this was a national policy change which aimed to tackle a major problem. Depression and comorbid depression are a leading cause of work disability in the London borough of Lambeth. However, working age adults with these conditions are less likely to benefit from adjustments on the fit note. Access to treatment in the year after receiving a fit note for a mental health condition is better than expected but varies by ethnicity. An ongoing engagement with the needs of workers and their employers is required to for the fit note to facilitate early access to treatment and work adjustments for working age adults with long-term conditions. This thesis has found that the fit note is not working as it was designed to. The use of cluster trials could have improved the implementation of the fit note and could inform future developments.
Date of Award1 Mar 2021
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorMatthew Hotopf (Supervisor), Ira Madan (Supervisor) & Stephani Hatch (Supervisor)

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