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Table 4 Univariate and multivariate Cox proportional hazard analysis for drug discontinuation due to inefficacy and adverse events

From: Persistence with anti-tumour necrosis factor therapies in patients with psoriatic arthritis: observational study from the British Society of Rheumatology Biologics Register

Variable

Overall withdrawal

Withdrawal due to inefficacy

Withdrawal due to adverse events

 

Univariate analysis

Multivariate analysis

Univariate analysis

Multivariate analysis

Univariate analysis

Multivariate analysis

Demographic

      

   Age at start of therapy (years)

0.99 (0.98 to 1.00)

0.99 (0.98 to 1.00)

0.99 (0.97 to 1.01)

0.99 (0.96 to 1.01)

0.98 (0.95 to 1.01)

0.96 (0.93 to 1.00)

   Female

1.38* (1.12 to 1.70)

1.29* (1.01 to 1.65)

1.48 (0.92 to 2.37)

1.45 (0.82 to 2.64)

1.64 (0.87 to 3.09)

1.58 (0.78 to 3.22)

   Smoking (yes/no)

1.36* (1.09 to 1.68)

1.22 (0.96 to 1.55)

1.70* (1.03 to 2.81)

1.51 (0.87 to 2.64)

1.10 (0.59 to 2.07)

0.97 (0.49 to 1.89)

   Co-morbiditya (yes/no)

1.77* (1.39 to 2.25)

1.49* (1.13 to 1.96)

1.64 (0.97 to 2.80)

1.17 (0.64 to 2.12)

2.68* (1.23 to 5.85)

2.67* (1.16 to 6.15)

Start year of therapyb

      

   2003

0.79 (0.56 to 1.13)

0.95 (0.98 to 2.21)

0.84 (0.37 to 1.95)

0.99 (0.73 to 5.44)

1.25 (0.42 to 3.72)

0.92 (0.70 to 3.04)

   2004

0.65* (0.46 to 0.93)

0.93 (0.87 to 2.03)

0.71 (0.31 to 1.64)

0.81 (0.64 to 5.12)

0.70 (0.22 to 2.23)

0.96 (0.44 to 5.49)

   2005

0.52* (0.34 to 0.80)

0.93 (0.74 to 2.19)

0.68 (0.26 to 1.79)

0.92 (0.61 to 7.45)

0.52 (0.13 to 2.19)

0.95 (0.28 to 7.55)

   2006

0.43 (0.18 to 1.03)

0.94 (0.73 to 2.12)

0.99 (0.19 to 4.95)

0.94 (0.62 to 6.64)

0.99 (0.99 to 1.00)

0.93 (0.28 to 5.65)

Disease

      

   Baseline HAQ

1.16* (1.03 to 1.29)

1.08 (0.95 to 1.22)

1.26* (1.02 to 1.55)

1.20 (0.95 to 1.49)

1.16 (0.83 to 1.62)

1.06 (0.71 to 1.59)

   Disease duration (years)

0.99 (0.98 to 1.00)

0.99 (0.98 to 1.01)

0.98 (0.95 to 1.00)

0.99 (0.97 to 1.03)

0.99 (0.96 to 1.03)

0.99 (0.95 to 1.03)

   Baseline DAS-28

0.93 (0.85 to 1.01)

0.88 (0.79 to 1.16)

0.88 (0.73 to 1.07)

0.83 (0.66 to 1.04)

0.88 (0.69 to 1.12)

0.89 (0.66 to 1.57)

   Inflammationc

0.93 (0.74 to 1.15)

--

0.72 (0.45 to 1.17)

--

1.18 (0.60 to 2.29)

--

   Tender joint counts

1.00 (0.99 to 1.01)

--

0.99 (0.97 to 1.03)

--

1.00 (0.96 to 1.04)

--

   Swollen joint counts

0.97* (0.96 to 0.99)

--

0.98 (0.94 to 1.02)

--

0.99 (0.94 to 1.04)

--

Therapeutic – concurrent use of:

      

   Methotrexate

0.89 (0.72 to 1.09)

0.64 (0.49 to 1.12)

1.03 (0.64 to 1.67)

0.65 (0.36 to 1.18)

1.06 (0.57 to 1.99)

0.67 (0.32 to 1.39)

   Sulfasalazine

0.49 (0.29 to 1.15)

0.30 (0.13 to 1.19)

0.40 (0.10 to 1.64)

0.32 (0.04 to 2.36)

0.68 (0.16 to 2.81)

1.54 (0.34 to 6.92)

   Steroids

1.22 (0.96 to 1.57)

1.06 (0.81 to 1.38)

1.14 (0.65 to 2.01)

0.91 (0.49 to 1.71)

1.89 (0.98 to 3.66)

1.92 (0.95 to 3.89)

Biological therapyd

      

   Infliximab

2.30* (1.85 to 2.87)

2.80* (2.12 to 3.70)

2.62* (1.59 to 4.34)

3.77* (1.96 to 7.24)

2.42* (1.26 to 4.68)

3.12* (1.41 to 6.89)

   Adalimumab

1.11 (0.78 to 1.59)

1.00 (0.67 to 1.51)

1.81 (0.89 to 3.65)

1.62 (0.70 to 3.78)

1.11 (0.37 to 3.33)

0.74 (0.21 to 2.66)

  1. Drug discontinuation due to inefficacy and adverse events. Data presented as hazard ratio (95% confidence interval). DAS-28, 28-joint disease activity score; HAQ, Health assessment questionnaire. aIncludes any of hypertension, angina, ischaemic heart disease, stroke, pulmonary fibrosis, asthma, chronic obstructive pulmonary disease, diabetes, thyroid disease, peptic ulcers, hepatic disease, renal disease, demyelinating disease, epilepsy, depression, tuberculosis, cancer. bReference category, 2002. cInflammation (C-reactive protein >20 mg/l or erythrocyte sedimentation rate >28 mm/hour). dReference category, etanercept. * P < 0.05.