Can we predict the outcome for people with patellofemoral pain? A systematic review on prognostic factors and treatment effect modifiers

Abstract

BackgroundPatellofemoral pain (PFP) is a multifactorial and often persistent knee condition. One strategy to enhance patient outcomes is using clinically assessable patient characteristics to predict the outcome and match a specific treatment to an individual.AimA systematic review was conducted to determine which baseline patient characteristics were (1) associated with patient outcome (prognosis); or (2) modified patient outcome from a specific treatment (treatment effect modifiers).Methods6 electronic databases were searched (July 2016) for studies evaluating the association between those with PFP, their characteristics and outcome. All studies were appraised using the Epidemiological Appraisal Instrument. Studies that aimed to identify treatment effect modifiers underwent a checklist for methodological quality.ResultsThe 24 included studies evaluated 180 participant characteristics. 12 studies investigated prognosis, and 12 studies investigated potential treatment effect modifiers. Important methodological limitations were identified. Some prognostic studies used a retrospective design. Studies aiming to identify treatment effect modifiers often analysed too many variables for the limiting sample size and typically failed to use a control or comparator treatment group. 16 factors were reported to be associated with a poor outcome, with longer duration of symptoms the most reported (>4 months). Preliminary evidence suggests increased midfoot mobility may predict those who have a successful outcome to foot orthoses.ConclusionsCurrent evidence can identify those with increased risk of a poor outcome, but methodological limitations make it difficult to predict the outcome after one specific treatment compared with another. Adequately designed randomised trials are needed to identify treatment effect modifiers.

Which treatment is most effective for patients with patellofemoral pain? A protocol for a living systematic review including network meta-analysis

“…The following factors are considered for exploration when sufficient data are available (>10 studies/events per variable), in the following order: diagnostic approach used (clinical vs imaging), pain intensity, symptom duration, active or sedentary population, age, sex (male/female), quality of life, unilateral versus bilateral pain and publication status (published/unpublished). 34 35 …”

Patellofemoral pain: One year results of a randomized trial comparing hip exercise, knee exercise, or free activity

“…This may limit its generalizability to primary care. The long pain duration may affect the prognosis, as pain duration is a negative prognostic factor . A further limitation is the inability to quantify the activity level of the control group during the intervention period.…”

“…The long pain duration may affect the prognosis, as pain duration is a negative prognostic factor. 46 A further limitation is the inability to quantify the activity level of the control group during the intervention period. A higher rate of missing data for muscle strength testing at 12 months limits the robustness of these measures.…”

Capturing patient-reported area of knee pain: a concurrent validity study using digital technology in patients with patellofemoral pain

“…Interestingly, when the knee pain drawings were compared to duration of symptoms, those with a longer duration of symptoms appeared to draw patterns more of an ‘O’ shape. Given that longer duration of PFP symptoms has been shown to be a prognostic indicator of a poor outcome ( Matthews et al, 2016 ), capturing pain areas digitally will allow quantification and real time insight into the patient’s condition, which may optimise patient management.…”