ADHD has been associated with high health-related resource utilisation and a substantial economic burden on the health system. Despite a disproportionate prevalence of ADHD among prison inmates, the health-related and economic impact of ADHD in this population remains unknown. This observational study aimed to assess the effect of ADHD on HRQoL in imprisoned adults, and to determine the extent of medical and prison service use and costs related to ADHD among this population.
Participants* were recruited by opportunity sampling from Porterfield Prison, Inverness, Scotland, between 2011 and 2013. All participants were evaluated for a diagnosis of ADHD using the Diagnostic Interview for ADHD in Adults 2.0 (DIVA-2.0)† and were asked whether they had previously received a diagnosis or treatment for ADHD or any other psychiatric condition.
The impact of ADHD on the participants’ HRQoL was assessed using the Health Utilities Index mark 3 (HUI3),‡ whereby participants were asked to answer 41 questions based on their health status in the last 4 weeks, allowing calculation of HRQoL utility scores across eight attributes (vision, hearing, speech, ambulation, dexterity, emotion, cognition and pain), as well as a composite HRQoL score, which was used to calculate quality-adjusted life years (QALY) and was extrapolated to 1 year. Type I Tobit models adjusted for age were used to estimate the association between ADHD and each HUI3 attribute. Since the emotion domain of the HUI3 may be sensitive to psychiatric comorbidities, models for all HUI3 variables were further adjusted for comorbid anxiety and depression standardised symptom scores.
Participants’ use of medical services was evaluated using data from prison medical records, and included appointments with a GP, nurse, psychiatrist or psychologist, or any other type of health-related visit. Costs associated with these visits were calculated using reference costs reported by the National Health Service. Medication costs were not explicitly collected in the study. Use of prison services was assessed using data obtained from prison records of behavioural incidents involving participants, with associated costs calculated based on reference costs reported by the UK Ministry of Justice and HM Prison Service, and adjusted using the Consumer Price Index. All costs were assessed based on the previous 3 months, and were then calculated for 1 year, assuming similar patterns of service use.
A total of 390 male participants* (average age, 30.3 [standard deviation (SD) 8.3] years; Caucasian British, 99.0%) took part in the study. ADHD was diagnosed in 96 participants, and of these, 18 (18.8%) reported a previous diagnosis of ADHD and 15 (15.6%) reported having received pharmacological treatment for ADHD in the past.
The results showed that:
- Participants with ADHD had a significantly lower mean age than those without ADHD (28.2 [SD 7.5] years vs 31.0 [SD 8.5] years, respectively; p<0.01).
- Participants with ADHD had significantly lower HRQoL utility scores than those without ADHD in the HUI3 attributes of speech (mean score 0.952 vs 0.971; p=0.028), pain (0.792 vs 0.874; p=0.012), ambulation (0.974 vs 0.997; p=0.007), emotion (0.692 vs 0.817; p<0.001) and cognition (0.709 vs 0.879; p<0.001).
- Even after adjustment for age, comorbid anxiety and depression, and correction for missing values, HRQoL scores remained significantly lower for vision, ambulation, cognition and QALY for participants with ADHD compared with those without ADHD.
- Participants with ADHD had significantly lower HRQoL scores for emotion, hearing and pain when the model was adjusted for age; however, these associations were not significant when the model was adjusted for comorbid anxiety and depression.
- Participants with ADHD had significantly lower composite HRQoL scores than those without ADHD (mean score 0.477 vs 0.699; p<0.001), and the proportion of participants with a composite HRQoL score >0.90 (‘healthy state’) was substantially greater among participants without ADHD compared with those with ADHD.
- Participants with ADHD had a significantly greater number of visits to GPs (incidence rate ratio [IRR] 1.21, 95% confidence interval [CI] 1.00–1.45; p=0.04), physical health nurses (IRR 1.25, 95% CI 1.03–1.50; p=0.02) and mental health nurses (IRR 1.84, 95% CI 1.19–2.85; p=0.01) than those without ADHD in the previous 3 months, although no significant differences were observed for other health-related visits.
- Costs associated with medical service use were significantly greater for participants with ADHD compared with those without ADHD (predicted cost margin over 1 year, £543.60; p<0.05); however, there was no significant difference in costs related to use of prison services (predicted cost margin over 1 year, £45.60; p>0.05).
- The estimated total annual costs for medical and prison service use were £590 more for participants with ADHD compared with those without ADHD (p<0.01).
There were several limitations to the study. First, the sample population was all-male and predominantly Caucasian British, and therefore these results may not be generalisable to the wider prison population. Second, ADHD diagnosis was based on self-reported information, with recall bias unaccounted for, which could have affected data on ADHD symptom measures and service use. Additionally, ‘don’t know’ was an answer option for all questions on the HUI3, potentially leading to large amounts of missing data, which could introduce bias into HUI3 attribute-specific scores. However, the use of the Naeim imputation method to select the most plausible answer in the case of ‘don’t know’ responses, in addition to a sensitivity analysis performed on only participants with complete HUI3 data, addressed this limitation. Finally, the extrapolation of data collected over a 3-month period to provide 1-year estimates may be limited in its accuracy.
The authors concluded that HRQoL is considerably poorer in adult male prison inmates with ADHD than those without ADHD, with an adjusted reduction of 0.13 QALY, and that ADHD affects a wide range of health attributes and impacts on QoL through emotional and cognitive dysfunction, impaired executive functioning and comorbid psychiatric disorders. This places a significant economic burden of ADHD on the prison system, driven by increased use of medical services among prisoners with ADHD compared with those without. The authors indicated that there is a need for increased awareness of ADHD in the prison system, and suggested that an ADHD screen should be introduced on admission to prison services.
Read more about ADHD in adult male prison inmates here
*Participants were indirectly compensated for taking part in the study via a donation of £20 per participant into a Prison Common Good Fund. The fund was then used to purchase items that could be used by all prisoners to enhance prison life. All participants provided written consent to take part in the study
†The DIVA-2.0 is a semi-structured clinical interview used to diagnose ADHD in adults according to the Diagnostic and Statistical Manual of Mental Disorders – 5th Edition criteria. Participants answered questions relating to current and childhood (between the ages of 5 and 12 years) symptoms of ADHD and the scope of impairment they experienced.
‡The HUI3 scoring system provides HRQoL utility scores on a scale from 0.00 (‘dead’) to 1.00 (‘perfect health’), and meets criteria for calculating QALY
Young S, González RA, Fridman M, et al. The economic consequences of attention deficit hyperactivity disorder in the Scottish prison system. BMC Psychiatry 2018; 18: 210.