INTRODUCTION
A 2004 study determined that the prevalence of diagnosed
psoriasis was 3.15%, which is the equivalent of
approximately 5 million adults, while the National Psoriasis
Foundation estimates that the number may be as high as
7.5 million Americans.1,2 Psoriasis is more than an annoyance,
and nearly 60% of those diagnosed with psoriasis report that
their disease is a large problem in their daily life.3
Many individuals with moderate or severe psoriasis are not receiving
any form of treatment or are undertreated. A 2007 study
determined that 39% of patients categorized as having severe
psoriasis and 37% of patients categorized as having moderate
psoriasis were not receiving any form of treatment.4 Additionally,
35% of those who were diagnosed with moderate to severe
psoriasis were treated with only topical treatments.4
With the introduction of biologics, safer systemic treatment
options are available for patients with moderate-to-severe psoriasis,
and these may be addressing past under-treatment of
the disease. We sought to characterize the trends in systemic
treatment for psoriasis over time.
METHODS
Data from annual surveys from the National Ambulatory Medical
Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 1993 through 2010 were
analyzed. These surveys provide information on outpatient visits
to non-federally employed outpatient physicians and the
outpatient and emergency departments of short-stay hospitals,
such as patient demographics, reasons provided by the patient
for the visit, and any medications or therapies prescribed.
The rate of response to the NAMCS varied from 58.3% in 2010
to 73.0% in 1995 and 1993 over the 18-year period, with an average
response rate of 65.6%, while the rate of response to the
NHAMCS varied from 98.0% in 1998 to 89.4% in 2007 with an
average response rate of 93.1%. Estimates produced were calculated
with the weighting used by the NAMCS and NHAMCS
to adjust for nonresponse to produce both national and unbiased
estimates. All data analysis was performed using SAS
9.1.3 (SAS Institute, Cary, NC).
For the present study, visits with a diagnosis of psoriasis and no
diagnosis of psoriatic arthritis were selected. Therapies analyzed
included phototherapy, methotrexate (MTX), systemic retinoids,
cyclosporine A (CSA), biologics, and systemic steroids. Phototherapy
was identified by procedure code 99.82, 99.83, or a
prescription for methoxsalen or psoralens. Retinoids included
acitretin and etretinate, but topical retinoids were excluded. Systemic
steroids included prednisone, methylprednisolone, and
