BACKGROUND: Clinical trials and observational studies lacking measures of health-related quality of life (QoL) are often inapplicable when conducting cost-effectiveness analyses using quality-adjusted life-years (QALYs). The only solution is to map QoL ex post from additionally collected clinical outcomes and generic QoL instruments. Nonetheless, mapping studies are absent in psoriatic arthritis (PsA). METHODS: In this 2-year, prospective, multicentre, non-interventional study of PsA patients, EQ-5D and key clinical parameters such as Disease Activity in PsA (DAPsA), clinical DAPsA (cDAPsA; DAPsA without C-reactive protein [CRP]), and Health Assessment Questionnaire disability index (HAQ) were collected. We employed a linear mixed-effect regression model (ME) of the longitudinal dataset to explore the best predictors of QoL. RESULTS: A total of 228 patients were followed over 873 appointments/observations. DAPsA, cDAPsA and HAQ were stable and highly significant predictors of EQ-5D utilities in both cross-sectional and longitudinal analyses. The best prediction was provided using a linear ME with HAQ and cDAPsA or DAPsA. A HAQ increase of 1 point represented a decrease in EQ-5D by -0.204 or -0.203 (p < 0.0001); a one-point increase in cDAPsA or DAPsA dropped EQ-5D equally by -0.005 (p < 0.0001). The ME revealed steeper and more accurate association compared with cross-sectional regressions or non-linear models/transformations. CONCLUSIONS: This is the first mapping study conducted in PsA and we hope that our study will encourage further mapping studies in PsA. The results showed that in cases where CRP is absent, cDAPsA provides similar results to DAPsA in predicting QoL.

3rd Internal Clinic University Hospital Olomouc Olomouc Czech Republic

Clinic of Rheumatology 1st Faculty of Medicine Charles University Prague Prague Czech Republic

Department of Clinical Pharmacology Rheumatology University Hospital Plzen Plzen Czech Republic

Institute of Health Economics and Technology Assessment Vaclavska 316 12 12000 Prague 2 Czech Republic

Institute of Rheumatology Prague Czech Republic

See more in PubMed

J Rheumatol. 2014 Apr;41(4):782-91 PubMed

Rev Bras Reumatol. 2010 Jan-Feb;50(1):31-43 PubMed

J Rheumatol. 2014 May;41(5):887-96 PubMed

Pharmacoeconomics. 1993 Nov;4(5):353-65 PubMed

Qual Life Res. 2014 Mar;23(2):431-42 PubMed

J Dermatolog Treat. 2015 Feb;26(1):23-31 PubMed

Health Policy. 1996 Jul;37(1):53-72 PubMed

Clin Exp Rheumatol. 2005 Sep-Oct;23(5 Suppl 39):S14-8 PubMed

Patient. 2017 Aug;10 (4):455-462 PubMed

Stat Med. 1997 Oct 30;16(20):2349-80 PubMed

Ann Rheum Dis. 2016 May;75(5):811-8 PubMed

Rheum Dis Clin North Am. 2015 Nov;41(4):545-68 PubMed

Expert Rev Pharmacoecon Outcomes Res. 2017 Apr;17 (2):203-211 PubMed

Eur J Health Econ. 2017 Jan;18(1):73-82 PubMed

Arthritis Res Ther. 2017 Mar 20;19(1):63 PubMed

Value Health. 2017 Jan;20(1):18-27 PubMed

J Rheumatol. 2017 Feb;44(2):193-200 PubMed

Clin Exp Rheumatol. 2012 Jul-Aug;30(4 Suppl 73):S126-31 PubMed

Semin Arthritis Rheum. 1973;3(1):55-78 PubMed

Eur J Health Econ. 2010 Apr;11(2):215-25 PubMed

J Clin Epidemiol. 2007 Jun;60(6):616-24 PubMed

Med Decis Making. 2012 Jan-Feb;32(1):56-69 PubMed

Value Health. 2016 Sep - Oct;19(6):704-719 PubMed

Pharmacoeconomics. 2013 Aug;31(8):643-52 PubMed

Indian Dermatol Online J. 2016 Nov-Dec;7(6):481-488 PubMed

Health Technol Assess. 2011 Mar;15(14 ):1-278 PubMed

Value Health Reg Issues. 2014 Sep;4:100-106 PubMed

Clin Exp Rheumatol. 2015 Sep-Oct;33(5 Suppl 93):S48-50 PubMed

Ann Rheum Dis. 2016 Mar;75(3):499-510 PubMed

Open Access Rheumatol. 2017 Mar 02;9:21-28 PubMed

Eur J Health Econ. 2014 May;15 Suppl 1:S35-43 PubMed

Pharmacoeconomics. 2015 Oct;33(10 ):993-1011 PubMed

Arthritis Rheum. 2006 Aug;54(8):2665-73 PubMed

Pharmacoeconomics. 2016 Jan;34(1):59-76 PubMed

Stat Med. 1998 Jun 15;17(11):1261-91 PubMed

World J Orthop. 2014 Sep 18;5(4):537-43 PubMed

Value Health Reg Issues. 2014 Sep;4:75-81 PubMed