Baselines relationship with outcome

The issue here is not just one of simplicity versus complexity. My personal view is that in the use of covariates and measurements generally there is much to be gained by using more complex models. This was the view as regards use of baselines and other covariates expounded in Chapter 7. The issue here, however, is to do with modelling of the relationship between outcome measures themselves rather than between outcome measures and baselines. This raises the problem of correction for post-baseline covariates. 

It is important to carefully document core ADHD symptoms at baseline to provide a reference point from which to evaluate effectiveness of treatment. Improvement in individualized patient outcomes are desired, such as (1) family and social relationships, (2) disruptive behavior, (3) completing required tasks, (4) self-motivation, (5) appearance, and (6) self-esteem. It is very important to elicit evaluations of the patient s behavior from family, school, and social environments in order to assess the preceding. Using standardized rating scales (e.g., Conners Rating Scales-Revised, Brown Attention-Deficit Disorder Scale, and IOWA Conners Scale) in both children and adults with ADHD helps to minimize variability in evaluation.29 After initiation of therapy, evaluations should be done every 2 to 4 weeks to determine efficacy of treatment, height, weight, pulse, and blood pressure. Physical examination or liver function tests may be used to monitor for adverse effects. 

The ratios of TIMP-1 MMP-1 and TIMP-LMMP-3 in blood have been reported to be significantly lower in patients with rheumatoid arthritis versus patients with nonrheumatoid arthritis (CIO). In rheumatoid arthritis patients, serum C-reactive protein correlated with MMP-3 and TIMP-1 levels, but not with MMP-1 levels. The number of erosions noted on X-rays correlated with baseline levels of MMP-3, but not TIMP-1. Cunnane et al. (CIO) postulated that treatment which inhibits the production and activation of MMP-1 may preferentially limit the formation of new joint erosions and improve the clinical outcome of patients with rheumatoid arthritis. In contrast to circulating levels of MMP-1, Keyszer et al. reported that MMPrTIMP complexes in blood correlate with rheumatoid activity scores (modified Lansbury Index and Keitel Function Index) in rheumatoid arthritis nonetheless, this relationship to disease activity was weaker than that of MMP-3 or C-reactive protein (K4). 

In this review we concentrate on individual-based studies. In case-control studies, subjects with already existing disease are retrospectively compared with control persons with respect to previous exposure. In cohort studies, individual exposure is measured at baseline and the cohort is followed over time for newly diagnosed outcome variables. Both case-control and cohort studies estimate the (relative) risk associated with exposure. Intervention studies utilize an experimental design and are mostly double blind trials with a defined treatment or placebo assigned randomly. Results from intervention studies, followed by cohort studies, make the greatest contributions to obtaining evidence of a causal relationship. Case-control studies are liable to particular bias, which give their results less credibility. 

---