Effectiveness of a Web-Based Physical Activity Intervention in Patients With Knee and/or Hip Osteoarthritis: Randomized Controlled Trial

Background

Patients with knee and/or hip osteoarthritis (OA) are less physically active than the general population, while the benefits of physical activity (PA) have been well documented. Based on the behavioral graded activity treatment, we developed a Web-based intervention to improve PA levels in patients with knee and/or hip OA, entitled “Join2move”. The Join2move intervention is a self-paced 9-week PA program in which the patient’s favorite recreational activity is gradually increased in a time-contingent way.

Objective

The aim of the study was to investigate whether a fully automated Web-based PA intervention in patients with knee and/or hip OA would result in improved levels of PA, physical function, and self-perceived effect compared with a waiting list control group.

Methods

The study design was a two-armed randomized controlled trial which was not blinded. Volunteers were recruited via articles in newspapers and health-related websites. Eligibility criteria for participants were: (1) aged 50-75 years, (2) self-reported knee and/or hip OA, (3) self-reported inactivity (30 minutes of moderate PA, 5 times or less per week), (4) no face-to-face consultation with a health care provider other than general practitioners, for OA in the last 6 months, (5) ability to access the Internet weekly, and (6) no contra-indications to exercise without supervision. Baseline, 3-month, and 12-month follow-up data were collected through online questionnaires. Primary outcomes were PA, physical function, and self-perceived effect. In a subgroup of participants, PA was measured objectively using accelerometers. Secondary outcomes were pain, fatigue, anxiety, depression, symptoms, quality of life, self-efficacy, pain coping, and locus of control.

Results

Of the 581 interested respondents, 199 eligible participants were randomly assigned to the intervention (n=100) or waiting list control group (n=99). Response rates of questionnaires were 84.4% (168/199) after 3 months and 75.4% (150/199) after 12 months. In this study, 94.0% (94/100) of participants actually started the program, and 46.0% (46/100) reached the adherence threshold of 6 out of 9 modules completed. At 3 months, participants in the intervention group reported a significantly improved physical function status (difference=6.5 points, 95% CI 1.8-11.2) and a positive self-perceived effect (OR 10.7, 95% CI 4.3-26.4) compared with the control group. No effect was found for self-reported PA. After 12 months, the intervention group showed higher levels of subjective (difference=21.2 points, 95% CI 3.6-38.9) and objective PA (difference=24 minutes, 95% CI 0.5-46.8) compared with the control group. After 12 months, no effect was found for physical function (difference=5 points, 95% CI −1.0 to 11.0) and self-perceived effect (OR 1.2, 95% CI 0.6-2.4). For several secondary endpoints, the intervention group demonstrated improvements in favor of the intervention group.

Conclusions

Join2move resulted in changes in the desired direction for several primary and secondary outcomes. Given the benefits and its self-help format, Join2move could be a component in the effort to enhance PA in sedentary patients with knee and/or hip OA.

Trial Registration

The Netherlands National Trial Register: NTR2483; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2483 (Archived by WebCite at http://www.webcitation.org/67NqS6Beq).     

Vitamin D binding protein is a key determinant of 25‐hydroxyvitamin D levels in infants and toddlers

Circulating 25‐hydroxyvitamin D (25‐OHD) levels vary among human populations. Only limited information regarding determinants of these measures is available for infants and children, particularly in minority groups at greatest risk for vitamin D deficiency. We identified demographic determinants of circulating 25‐OHD in a large cohort of minority children, and now extend our studies to examine potential roles of vitamin D binding protein (DBP) as a determinant of 25‐OHD levels. Serum DBP level and common single nucleotide polymorphisms (SNPs) at positions 432 and 436 in the GC gene, encoding DBP, were examined. We confirmed self‐reported ancestry using ancestry informative markers (AIMs), and included quantitative AIMs scores in the analysis. The multivariate model incorporated previously identified demographic and nutritional determinants of 25‐OHD in this cohort, as well as GC SNPs and circulating DBP. Genetic variants in GC differed by self‐reported ancestry. The 1f allele (D432/T436) was enriched in African Americans, occurring in 71%. Homozygosity for the 1f allele (DDTT) occurred in 53% of African Americans but only 6% of Caucasians and 13% of Hispanics. Circulating DBP was significantly correlated with 25‐OHD. GC SNPs were associated with both circulating DBP and 25‐OHD. It appears that progressive substitution of lysine for threonine at the 436 position results in lower circulating 25‐OHD. Multivariate analysis revealed that genetic variance in GC significantly contributes to circulating DBP as well as 25‐OHD. Moreover, the effect of GC SNPs on 25‐OHD are evident after adjusting for their effects on circulating DBP. Thus in young children genetic variance of the common GC T436K SNP affects circulating levels of the DBP protein, which in turn affects circulating 25‐OHD. However, the GC genotype also affects circulating 25‐OHD independently of its effect on circulating DBP. These findings provide data that may be important in the interpretation of vitamin D status in children of varying ancestral backgrounds. © 2013 American Society for Bone and Mineral Research     

Platelet-agglutinating protein P37 from a thrombotic thrombocytopenic purpura plasma forms a complex with human immunoglobulin G

We have previously reported the purification of a 37-kd platelet- agglutinating protein (PAP p37) from the plasma of a patient with thrombotic thrombocytopenic purpura (TTP) that was shown to be present in a subset of TTP patients. The platelet agglutination induced by PAP p37 has been shown to be inhibited by IgG from normal human adults and the same TTP patient after recovery. To elucidate the mechanism of inhibition of IgG, the interaction between PAP p37 and IgG was studied. The complex formation was demonstrated by the binding of fluid-phase IgG from normal adults and the same TTP patient after recovery to adsorbed PAP by using an enzyme-linked immunosorbent assay. The binding was specific, concentration dependent, and saturable. IgG purified from a 5-month-old baby and the same TTP patient during active disease did not form complex with PAP p37. The IgG covalently cross-linked to Sepharose 4B bound 125I-PAP p37 but not 125I-fibrinogen. Sucrose density gradient ultracentrifugation of a mixture of 125I-PAP p37 and IgG also revealed the fluid-phase complex formation with a sedimentation value of 19S. Complexes of molecular weight ranging from 180,000 to over 350,000 daltons were also detected by molecular sieve chromatography. The IgG that was bound to PAP p37 conjugated to Sepharose 4B inhibited the agglutination of washed platelets induced by TTP plasma containing PAP p37, whereas the IgG that was not bound to PAP p37 did not have a significant inhibitory effect. The complex formation between PAP p37 and specific IgG is likely to account for the in vitro inhibition of TTP plasma-induced agglutination and, at least partly, the in vivo successful treatment with specific IgG-containing normal plasma.