Correspondence 995
provide data on this point after excluding individuals who were on therapy with biologics or DMARDs. It would be helpful also if the authors could provide data on the performance of the three questionnaires among the screened positive group for non-PsA diagnoses, such as osteoarthritis. In summary, the PASE questionnaire is a brief and practical screening tool focused on the patient with already diagnosed psoriasis in the dermatology clinic setting. PASE may also correlate with psoriatic arthritis disease activity and response to therapy, its sensitivity is highest and it performs better in patients naive to systemic therapy based on this study. We would like to emphasize that when comparing screening tools it is most helpful to be aware of the underlying premise of the tools and their appropriate clinical use. 1
Department of Dermatology, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. 2 Division of Rheumatology, Allergy and Immunology, Department of Medicine, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. 3 Department of Rheumatologic and Immunologic Disease, Cleveland Clinic, Cleveland, OH, U.S.A. 4 Channing Division of Network Medicine, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. Correspondence: Abrar A. Qureshi. E-mail: [email protected]
J.F. MEROLA1,2 M.E. HUSNI3 A.A. QURESHI1,4
References 1 Coates LC, Aslam T, Al Balushi F et al. Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study). Br J Dermatol 2013; 168:802–7. 2 Dominguez PL, Husni ME, Holt EW et al. Validity, reliability, and sensitivity-to-change properties of the psoriatic arthritis screening and evaluation questionnaire. Arch Dermatol Res 2009; 301:573–9. 3 Gladman DD, Schentag CT, Tom BD et al. Development and initial validation of a screening questionnaire for psoriatic arthritis: the Toronto Psoriatic Arthritis Screen (ToPAS). Ann Rheum Dis 2009; 68:497–501. 4 Husni ME, Meyer KH, Cohen DS et al. The PASE questionnaire: pilot-testing a psoriatic arthritis screening and evaluation tool. J Am Acad Dermatol 2007; 57:581–7. 5 Ibrahim GH, Buch MH, Lawson C et al. Evaluation of an existing screening tool for psoriatic arthritis in people with psoriasis and the development of a new instrument: the Psoriasis Epidemiology Screening Tool (PEST) questionnaire. Clin Exp Rheumatol 2009; 27:469–74. Funding sources: No external funding. Conflicts of interest: A.A.Q. has licensed the PASE questionnaire to Merck and Pfizer, has received a grant from Amgen, and is a consul-
© 2014 British Association of Dermatologists
tant for Jansen, Novartis and Abbott. J.F.M. is a consultant for Biogen IDEC, an investigator for Amgen and has served on an advisory board for Amgen. M.E.H. has licensed the PASE questionnaire as above, and has also acted as a consultant for UCB, Amgen, Novartis, Bristol Myers Squibb and Abbott.
Psoriatic arthritis screening tools: study design and methodologic challenges – reply from authors DOI: 10.1111/bjd.12824 DEAR EDITOR, We thank Dr Qureshi et al. (‘Psoriatic arthritis screening tools: study design and methodologic challenges’)1 for their comments about our study [‘Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study)’].2 The CONTEST study was carried out in dermatology clinics only. As they point out, there would be little point in administering these instruments in rheumatology clinics. The low response rate is disappointing, but reflects the likely response to the use of such tools in clinical practice. We would indicate that our sample size was almost fully achieved so the study had sufficient power to compare the three instruments. Unless Dr Qureshi et al. feel that the Psoriatic Arthritis Screening and Evaluation tool was specifically disadvantaged by the nonresponders, we can’t see why the study failed to be a fair comparison of the three tools administered in the setting for which they were designed to work. The limitations of study design were acknowledged in the Discussion. Clearly, examining only positive responders will give an overestimate of sensitivity and an underestimate of specificity, but this limitation applied to all three instruments equally. This statement is also true for those already on disease-modifying treatment, some of whom can still develop psoriatic arthritis de novo, and who present a particular challenge for treatment. Our statement in the Conclusion section of the Abstract comparing the instruments actually indicated that the Toronto Psoriatic Arthritis Screening tool and Psoriasis Epidemiology Project tool were slightly better at identifying psoriatic arthritis because of the slightly higher sensitivity of these instruments in this study. In this study it was also noticeable that the instruments performed differently in identifying articular and nonarticular (i.e. spinal and entheseal) forms of psoriatic arthritis, although the differences were not marked. This observation led us to suggest, in the Discussion, that a new instrument that combined features of each of the existing tools might perform better in identifying psoriatic arthritis and distinguishing psoriatic arthritis from other forms of arthritis.
British Journal of Dermatology (2014) 170, pp970–1001
996 Correspondence 1
LIMM Division of Rheumatic and Musculoskeletal Disease and NIHR Leeds Musculoskeletal Biomedical Research Unit, University of Leeds, Leeds, U.K. 2 Bradford Teaching Hospitals NHS Foundation Trust, Bradford, U.K. 3 Bart’s NHS Trust, London, U.K. 4 Western Infirmary, Glasgow, U.K. 5 Nottingham Independent Treatment Centre, Nottingham, U.K. 6 Prosser White Dermatology Centre, Wrightington, Wigan and Leigh NHS Foundation Trust, Wigan, U.K. 7 Dermatological Sciences, Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, The University of Manchester, Manchester, U.K. 8 Department of Dermatology, Leeds Teaching Hospitals NHS Trust, Leeds, U.K. 9 The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, U.K. 10 Guy’s and St Thomas’ NHS Foundation Trust, London, U.K. 11 Royal United Hospital, Bath, U.K. 12 Royal National Hospital for Rheumatic Diseases, Bath, U.K. 13 St John’s Institute of Dermatology, London, U.K. 14 Glasgow Royal Infirmary, NHS Greater Glasgow and Clyde, Glasgow, U.K. 15 Chapel Allerton Hospital, Chapeltown Road, Leeds LS7 4SA, U.K. Correspondence: Phillip S. Helliwell. E-mail: [email protected]
L.C. COATES1 T. ASLAM2 F. AL BALUSHI3 A.D. BURDEN4 E. BURDEN-TEH5 A.R. CAPERON1 R. CERIO3 C. CHATTOPADHYAY6 H. CHINOY7 M.J.D. GOODFIELD8 L. KAY9 S. KELLY3 B.W. KIRKHAM10 C.R. LOVELL11 H. MARZO-ORTEGA1 N. MCHUGH12 R. MURPHY5 N.J. REYNOLDS9 C.H. SMITH13 E.J.C. STEWART6 R.B. WARREN7 R. WAXMAN1 H.E. WILSON14 P.S. HELLIWELL1,2,15
References 1 Merola JF, Husni ME, Qureshi AA. Psoriatic arthritis screening tools: study design and methodologic challenges. Br J Dermatol 2014; 170:994–95. 2 Coates LC, Aslam T, Al Balushi F et al. Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study). Br J Dermatol 2013; 168:802–7. Funding sources: None. Conflicts of interest: None declared. © 2014 British Association of Dermatologists
Determination of the optimum operating point for a handheld minimal erythema dose device DOI: 10.1111/bjd.12793 DEAR EDITOR, Determination of a patient’s minimal erythema dose (MED) prior to narrowband ultraviolet B (NB-UVB) British Journal of Dermatology (2014) 170, pp970–1001
phototherapy is an established procedure. Currently there is no uniform methodology for acquiring the reading. Variations of the procedure include using canopies of fluorescent tubes or therapy cubicles in association with locally made templates. An economical MED device, consisting of a single PL-S 9W/01/2P NB-UVB fluorescent tube (emitting at 311 2 nm; Philips, Amsterdam, the Netherlands) fitted within a convenient and handheld enclosure was designed by Phil Saunders and Professor Brian Diffey of Newcastle Medical Physics Department. Equipped with 10 foil attenuating apertures (Fig. 1a), it allows irradiation of the skin at a selection of incremental doses with ratios of around 126. The device was validated by Otman et al. in 2006.1 Current advice is to switch on the unit 10 min prior to the test to allow the UV irradiance to stabilize, then after the test allowing it to cool for at least 15 min before reuse. Hence the device can be operated approximately once every half-hour. In some situations MEDs are requested within a shorter time frame than this cycle allows, limiting the rate at which patients can be tested. In addition a rapid turnaround may make contact with the skin uncomfortably warm. We sought a methodology that could increase the turnaround time of patients and improve temperature tolerance. Fluorescent tube output varies with temperature. Due to the unventilated construction of the enclosure, when left switched on for over 10 min the internal temperature of the device rises significantly, to over 60 °C, and the surface temperature of the apertures applied to the skin can be > 53 °C. By fitting an internal temperature probe, the unit can be calibrated over a tube temperature range stable enough to give sufficiently accurate measurements yet reducing the delays of the current warm-up or cool-down periods. It also provides a deterministic point at which to begin the MED and removes the ambient temperature variable (Fig. 1b). We measured the output of the device at the fully open aperture using an Avantes Ava Spec 2048 spectrometer with optical fibre input optics fitted with a Teflon diffuser [Avantes (U.K.) Ltd, Leatherhead, Surrey]. The measurement system was calibrated using a deuterium/halogen calibration lamp (Avantes Avalight DHS) with accuracy traceable back to national standards. Six repeated series of measurements were averaged over the temperature range 25–60 °C at 1 °C intervals. Over the temperature range 29–40 °C, the output of the device ranged from just before to just after its peak irradiance. The overall variation within this range was on average < 5% (Fig. 2). The time to reach 29 °C depended on the ambient temperature. With an ambient temperature of 22 °C it took on average 1 min 35 s. The time taken to increase from 29 to 40 °C (the 5% variation around the peak) averaged 2 min 37 s, sufficient to give up to 1 J cm 2 accurately. To return to 29 °C from 40 °C took on average 10 min 55 s. As expected the output of this device varies with temperature. There is a range either side of the peak irradiance that allows accurate operation. This range can be correlated to the internal temperature of the sealed enclosure. We have found © 2013 British Association of Dermatologists
provide data on this point after excluding individuals who were on therapy with biologics or DMARDs. It would be helpful also if the authors could provide data on the performance of the three questionnaires among the screened positive group for non-PsA diagnoses, such as osteoarthritis. In summary, the PASE questionnaire is a brief and practical screening tool focused on the patient with already diagnosed psoriasis in the dermatology clinic setting. PASE may also correlate with psoriatic arthritis disease activity and response to therapy, its sensitivity is highest and it performs better in patients naive to systemic therapy based on this study. We would like to emphasize that when comparing screening tools it is most helpful to be aware of the underlying premise of the tools and their appropriate clinical use. 1
Department of Dermatology, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. 2 Division of Rheumatology, Allergy and Immunology, Department of Medicine, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. 3 Department of Rheumatologic and Immunologic Disease, Cleveland Clinic, Cleveland, OH, U.S.A. 4 Channing Division of Network Medicine, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA, U.S.A. Correspondence: Abrar A. Qureshi. E-mail: [email protected]
J.F. MEROLA1,2 M.E. HUSNI3 A.A. QURESHI1,4
References 1 Coates LC, Aslam T, Al Balushi F et al. Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study). Br J Dermatol 2013; 168:802–7. 2 Dominguez PL, Husni ME, Holt EW et al. Validity, reliability, and sensitivity-to-change properties of the psoriatic arthritis screening and evaluation questionnaire. Arch Dermatol Res 2009; 301:573–9. 3 Gladman DD, Schentag CT, Tom BD et al. Development and initial validation of a screening questionnaire for psoriatic arthritis: the Toronto Psoriatic Arthritis Screen (ToPAS). Ann Rheum Dis 2009; 68:497–501. 4 Husni ME, Meyer KH, Cohen DS et al. The PASE questionnaire: pilot-testing a psoriatic arthritis screening and evaluation tool. J Am Acad Dermatol 2007; 57:581–7. 5 Ibrahim GH, Buch MH, Lawson C et al. Evaluation of an existing screening tool for psoriatic arthritis in people with psoriasis and the development of a new instrument: the Psoriasis Epidemiology Screening Tool (PEST) questionnaire. Clin Exp Rheumatol 2009; 27:469–74. Funding sources: No external funding. Conflicts of interest: A.A.Q. has licensed the PASE questionnaire to Merck and Pfizer, has received a grant from Amgen, and is a consul-
© 2014 British Association of Dermatologists
tant for Jansen, Novartis and Abbott. J.F.M. is a consultant for Biogen IDEC, an investigator for Amgen and has served on an advisory board for Amgen. M.E.H. has licensed the PASE questionnaire as above, and has also acted as a consultant for UCB, Amgen, Novartis, Bristol Myers Squibb and Abbott.
Psoriatic arthritis screening tools: study design and methodologic challenges – reply from authors DOI: 10.1111/bjd.12824 DEAR EDITOR, We thank Dr Qureshi et al. (‘Psoriatic arthritis screening tools: study design and methodologic challenges’)1 for their comments about our study [‘Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study)’].2 The CONTEST study was carried out in dermatology clinics only. As they point out, there would be little point in administering these instruments in rheumatology clinics. The low response rate is disappointing, but reflects the likely response to the use of such tools in clinical practice. We would indicate that our sample size was almost fully achieved so the study had sufficient power to compare the three instruments. Unless Dr Qureshi et al. feel that the Psoriatic Arthritis Screening and Evaluation tool was specifically disadvantaged by the nonresponders, we can’t see why the study failed to be a fair comparison of the three tools administered in the setting for which they were designed to work. The limitations of study design were acknowledged in the Discussion. Clearly, examining only positive responders will give an overestimate of sensitivity and an underestimate of specificity, but this limitation applied to all three instruments equally. This statement is also true for those already on disease-modifying treatment, some of whom can still develop psoriatic arthritis de novo, and who present a particular challenge for treatment. Our statement in the Conclusion section of the Abstract comparing the instruments actually indicated that the Toronto Psoriatic Arthritis Screening tool and Psoriasis Epidemiology Project tool were slightly better at identifying psoriatic arthritis because of the slightly higher sensitivity of these instruments in this study. In this study it was also noticeable that the instruments performed differently in identifying articular and nonarticular (i.e. spinal and entheseal) forms of psoriatic arthritis, although the differences were not marked. This observation led us to suggest, in the Discussion, that a new instrument that combined features of each of the existing tools might perform better in identifying psoriatic arthritis and distinguishing psoriatic arthritis from other forms of arthritis.
British Journal of Dermatology (2014) 170, pp970–1001
996 Correspondence 1
LIMM Division of Rheumatic and Musculoskeletal Disease and NIHR Leeds Musculoskeletal Biomedical Research Unit, University of Leeds, Leeds, U.K. 2 Bradford Teaching Hospitals NHS Foundation Trust, Bradford, U.K. 3 Bart’s NHS Trust, London, U.K. 4 Western Infirmary, Glasgow, U.K. 5 Nottingham Independent Treatment Centre, Nottingham, U.K. 6 Prosser White Dermatology Centre, Wrightington, Wigan and Leigh NHS Foundation Trust, Wigan, U.K. 7 Dermatological Sciences, Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, The University of Manchester, Manchester, U.K. 8 Department of Dermatology, Leeds Teaching Hospitals NHS Trust, Leeds, U.K. 9 The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, U.K. 10 Guy’s and St Thomas’ NHS Foundation Trust, London, U.K. 11 Royal United Hospital, Bath, U.K. 12 Royal National Hospital for Rheumatic Diseases, Bath, U.K. 13 St John’s Institute of Dermatology, London, U.K. 14 Glasgow Royal Infirmary, NHS Greater Glasgow and Clyde, Glasgow, U.K. 15 Chapel Allerton Hospital, Chapeltown Road, Leeds LS7 4SA, U.K. Correspondence: Phillip S. Helliwell. E-mail: [email protected]
L.C. COATES1 T. ASLAM2 F. AL BALUSHI3 A.D. BURDEN4 E. BURDEN-TEH5 A.R. CAPERON1 R. CERIO3 C. CHATTOPADHYAY6 H. CHINOY7 M.J.D. GOODFIELD8 L. KAY9 S. KELLY3 B.W. KIRKHAM10 C.R. LOVELL11 H. MARZO-ORTEGA1 N. MCHUGH12 R. MURPHY5 N.J. REYNOLDS9 C.H. SMITH13 E.J.C. STEWART6 R.B. WARREN7 R. WAXMAN1 H.E. WILSON14 P.S. HELLIWELL1,2,15
References 1 Merola JF, Husni ME, Qureshi AA. Psoriatic arthritis screening tools: study design and methodologic challenges. Br J Dermatol 2014; 170:994–95. 2 Coates LC, Aslam T, Al Balushi F et al. Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study). Br J Dermatol 2013; 168:802–7. Funding sources: None. Conflicts of interest: None declared. © 2014 British Association of Dermatologists
Determination of the optimum operating point for a handheld minimal erythema dose device DOI: 10.1111/bjd.12793 DEAR EDITOR, Determination of a patient’s minimal erythema dose (MED) prior to narrowband ultraviolet B (NB-UVB) British Journal of Dermatology (2014) 170, pp970–1001
phototherapy is an established procedure. Currently there is no uniform methodology for acquiring the reading. Variations of the procedure include using canopies of fluorescent tubes or therapy cubicles in association with locally made templates. An economical MED device, consisting of a single PL-S 9W/01/2P NB-UVB fluorescent tube (emitting at 311 2 nm; Philips, Amsterdam, the Netherlands) fitted within a convenient and handheld enclosure was designed by Phil Saunders and Professor Brian Diffey of Newcastle Medical Physics Department. Equipped with 10 foil attenuating apertures (Fig. 1a), it allows irradiation of the skin at a selection of incremental doses with ratios of around 126. The device was validated by Otman et al. in 2006.1 Current advice is to switch on the unit 10 min prior to the test to allow the UV irradiance to stabilize, then after the test allowing it to cool for at least 15 min before reuse. Hence the device can be operated approximately once every half-hour. In some situations MEDs are requested within a shorter time frame than this cycle allows, limiting the rate at which patients can be tested. In addition a rapid turnaround may make contact with the skin uncomfortably warm. We sought a methodology that could increase the turnaround time of patients and improve temperature tolerance. Fluorescent tube output varies with temperature. Due to the unventilated construction of the enclosure, when left switched on for over 10 min the internal temperature of the device rises significantly, to over 60 °C, and the surface temperature of the apertures applied to the skin can be > 53 °C. By fitting an internal temperature probe, the unit can be calibrated over a tube temperature range stable enough to give sufficiently accurate measurements yet reducing the delays of the current warm-up or cool-down periods. It also provides a deterministic point at which to begin the MED and removes the ambient temperature variable (Fig. 1b). We measured the output of the device at the fully open aperture using an Avantes Ava Spec 2048 spectrometer with optical fibre input optics fitted with a Teflon diffuser [Avantes (U.K.) Ltd, Leatherhead, Surrey]. The measurement system was calibrated using a deuterium/halogen calibration lamp (Avantes Avalight DHS) with accuracy traceable back to national standards. Six repeated series of measurements were averaged over the temperature range 25–60 °C at 1 °C intervals. Over the temperature range 29–40 °C, the output of the device ranged from just before to just after its peak irradiance. The overall variation within this range was on average < 5% (Fig. 2). The time to reach 29 °C depended on the ambient temperature. With an ambient temperature of 22 °C it took on average 1 min 35 s. The time taken to increase from 29 to 40 °C (the 5% variation around the peak) averaged 2 min 37 s, sufficient to give up to 1 J cm 2 accurately. To return to 29 °C from 40 °C took on average 10 min 55 s. As expected the output of this device varies with temperature. There is a range either side of the peak irradiance that allows accurate operation. This range can be correlated to the internal temperature of the sealed enclosure. We have found © 2013 British Association of Dermatologists
