Purpose: The etiology of pain in osteoarthritis (OA) is complex andmultifactorial. A growing number of studies suggest that modificationof pain-transmission in the peripheral and central nervous system,leading to sensitization, plays a role in OA pain. Sensitization seems tobe associated with neuropathic pain-like symptoms and assessment ofthese symptoms can help to identify patients who could benefit fromadditional treatment options. Several questionnaires are available todistinguish neuropathic from nociceptive pain symptoms. The modifiedpainDETECT questionnaire (mPDQ) is a self-reported questionnairedeveloped to discriminate between nociceptive- and possible/likelyneuropathic pain in knee OA patients. Recently the mPDQ was translatedinto Dutch and adjusted to also fit hip OA patients. The aim of thisstudy was to assess the validity of the mPDQ-NL in patients with hip orknee OA.Methods: Primary hip and knee OA patients were recruited from threeDutch hospitals. Based on previous research, confirmatory factor analysisfor two principal components was performed to assess structuralvalidity. Construct validity (both convergent and divergent) wasassessed using hypothesis testing. Predefined hypotheses were formulatedconcerning the correlation between the mPDQ-NL and theSelf-reported Leeds Assessment of Neuropathic Symptoms and Signs (SLANSS),subscales of the Knee injury and Osteoarthritis Outcome score/Hip disability and Osteoarthritis Outcome Score (KOOS/HOOS), VisualAnalogue Scale for pain (VAS pain), and subscales of the RAND-36health survey (RAND-36). According to the COSMIN criteria, constructvalidity of a questionnaire is sufficient if 75% of predefined hypothesesare met. Additionally, convergent validity was assessed with blunt PainPressure Thresholds (PPTs) in a subsample of participants. A reducedPPT is a somatosensory abnormality that is considered an indication ofsensitization in OA. Therefore it was expected that reduction of PPTswas associated with higher mPDQ scores.Results: 168 participants were included. PPT measurements wereperformed in a sample of 46 participants. Factor analysis confirmed twoprincipal components. The items that loaded on the first componentcould be described as “evoked neuropathic sensations”, the items thatloaded on the second component as “spontaneous neuropathic sensations”.However there were two items that substantially loaded on bothcomponents. The item regarding pain pattern did not load on anycomponent. Considering construct analysis, 80% of the predefinedhypotheses concerning the correlation between mPDQ and self-reportedquestionnaires were met. Considering the correlation with PPTmeasurements, 50% of the predefined hypotheses were met.Conclusions: The mPDQ-NL seems to adequately reflect neuropathicpain-like symptoms experienced by hip and knee OA patients. Concerningstructural validity, two determinative components seem to bepresent, in line with previous research. However, one particular itemregarding pain pattern might not reflect the construct of neuropathicpain-like symptoms in hip or knee OA. Therefore, when using the mPDQin hip or knee OA patients, it might be considered to skip this particularitem. Construct validity can be considered sufficient, with over 75% ofthe predefined hypotheses regarding correlation between the mPDQNLand other questionnaires were met. However, only 50% of the hypotheses concerning PPT measurements were met, probably due toheterogeneity and limited sample size of this subgroup. To ourknowledge, this study is the first to assess the structural validity of themPDQ knee and hip by using factor analysis and to assess constructvalidity using elaborate hypothesis testing as proposed by the COSMINguidelines.
OBJECTIVE: Juvenile dermatomyositis (DM) is an inflammatory myopathy in which the immune system targets the microvasculature of the skeletal muscle and skin, leading to significant muscle weakness and exercise intolerance, although the precise etiology is unknown. The goal of this study was to investigate the changes in exercise capacity in children with myositis during active and inactive disease periods and to study the responsiveness of exercise parameters.METHODS: Thirteen children with juvenile DM (mean+/-SD age 11.2+/-2.6 years) participated in this study. Patients performed a maximal exercise test using an electronically braked cycle ergometer and respiratory gas analysis system. Exercise parameters were analyzed, including peak oxygen uptake (VO2peak), peak work rate (Wpeak), and ventilatory anaerobic threshold (VAT). All children were tested during an active period of the disease and during a remission period. From these data, 4 different response statistics were calculated.RESULTS: The children performed significantly better during a remission period compared with a period of active disease. Most exercise parameters showed a very large response. The 5 most responsive parameters were Wpeak, Wpeak (percent predicted), oxygen pulse, VO2peak, and power at the VAT.CONCLUSION: We found in our longitudinal study that children with active juvenile DM had significantly reduced exercise parameters compared with a remission period. Moreover, we found that several parameters had very good responsiveness. With previously established validity and reliability, exercise testing has been demonstrated to be an excellent noninvasive instrument for the longitudinal followup of children with myositis.
Objectives The aim of this study was to examine the reciprocal association between work–family conflict and depressive complaints over time. Methods Cross-lagged structural equation modeling (SEM) was used and three-wave follow-up data from the Maastricht Cohort Study with six years of follow-up [2416 men and 585 women at T1 (2008)]. Work–family conflict was operationalized by distinguishing both work–home interference and home–work interference, as assessed with two subscales of the Survey Work–Home Interference Nijmegen. Depressive complaints were assessed with a subscale of the Hospital Anxiety and Depression scale. Results The results showed a positive cross-lagged relation between home–work interference and depressive complaints. The results of the χ 2 difference test indicated that the model with cross-lagged reciprocal relationships resulted in a significantly better fit to the data compared to the causal (Δχ 2 (2)=9.89, P=0.001), reversed causation model (Δχ 2 (2)=9.25, P=0.01), and the starting model (Δχ 2 (4)=16.34, P=0.002). For work–home interference and depressive complaints, the starting model with no cross-lagged associations over time had the best fit to the empirical data. Conclusions The findings suggest a reciprocal association between home–work interference and depressive complaints since the concepts appear to affect each other mutually across time. This highlights the importance of targeting modifiable risk factors in the etiology of both home–work interference and depressive complaints when designing preventive measures since the two concepts may potentiate each other over time.
