Pain Hypervigilance is Associated with Greater Clinical Pain Severity and Enhanced Experimental Pain Sensitivity Among Adults with Symptomatic Knee Osteoarthritis

Background

Pain hypervigilance is an important aspect of the fear-avoidance model of pain that may help explain individual differences in pain sensitivity among persons with knee osteoarthritis (OA).

Purpose

The purpose of this study was to examine the contribution of pain hypervigilance to clinical pain severity and experimental pain sensitivity in persons with symptomatic knee OA.

Methods

We analyzed cross-sectional data from 168 adults with symptomatic knee OA. Quantitative sensory testing was used to measure sensitivity to heat pain, pressure pain, and cold pain, as well as temporal summation of heat pain, a marker of central sensitization.

Results

Pain hypervigilance was associated with greater clinical pain severity, as well as greater pressure pain. Pain hypervigilance was also a significant predictor of temporal summation of heat pain.

Conclusions

Pain hypervigilance may be an important contributor to pain reports and experimental pain sensitivity among persons with knee OA.     

Complications,outcomes, and need for fusion after minimally invasive posterior cervical foraminotomy and microdiscectomy

Background context

Posterior cervical foraminotomy (PCF) with or without microdiscectomy (posterior cervical discectomy [PCD]) is a frequently used surgical technique for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. Currently, these procedures are being performed with increasing frequency using advanced minimally invasive techniques. Although the safety and efficacy of minimally invasive PCF/PCD (MI-PCF/PCD) have been established, reports on long-term outcome and need for secondary surgical intervention at the index or adjacent level are lacking.

Purpose

To determine the rates of complications, long-term outcomes, and need for secondary surgical intervention at the index or adjacent level after MI-PCF and microdiscectomy.

Study design

Retrospective analysis of a prospective cohort.

Patient sample

Seventy patients treated with MI-PCF and/or MI-PCD for cervical radiculopathy.

Outcome measures

Visual Analog Scale for neck/arm (VAS_N/A) pain and Neck Disability Index (NDI).

Methods

Ninety-seven patients underwent MI-PCF with or without MI-PCD between 2002 and 2011. Adequate prospective follow-up was available for 70 patients (95 cervical levels). The primary outcome assessed was need for secondary surgical intervention at the index or adjacent level. The secondary outcomes assessed included complications and improvements in NDI and VAS_N/A scores. All complications were reviewed. Mixed-model analyses of variance with random subject effects and autoregressive first-order correlation structures were used to test for differences among NDI, VAS_A, and VAS_N measurements made over time while accounting for the correlation among repeated observations within a patient. All statistical hypothesis tests were conducted at the 5% level of significance.

Results

Patients were followed for a mean of 32.1 months. Of 70 patients operated, there were 3 (4.3%) complications (1 cerebrospinal fluid leak, 1 postoperative wound hematoma, and 1 radiculitis), none of which required a secondary operative intervention. Five patients required an anterior cervical discectomy and fusion (eight total levels fused) on average 44.4 months after the index surgery. Of those, five (5.3%) were at the index level and three (2.1%) were at adjacent levels. Neck Disability Index scores improved significantly (p<.0001) immediately postoperatively and continued to decrease gradually with time. Visual Analog Scale for neck/arm scores improved significantly (p<.0001) from baseline immediately postoperatively but tended to plateau with time.

Conclusions

Minimally invasive PCF with or without MI-PCD is an excellent alternative for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. There is a low rate (1.1% per index level per year) of future index site fusion and a very low rate (0.9% per adjacent level per year) of adjacent-level disease requiring surgery.     

Systemic lupus erythematosus in three ethnic groups. XX. Damage as a predictor of further damage

OBJECTIVE: To examine the predictors of damage in a multiethnic cohort of systemic lupus erythematosus (SLE) patients with a specific focus on damage at baseline. Patients and METHODS: SLE patients from a multiethnic US (Hispanic, African-American and Caucasian) cohort (LUMINA: Lupus in Minority populations, Nature versus nurture) were included if they had > or =6 months of follow-up in the cohort. Damage was measured with the Systemic Lupus International Collaborating Clinics (SLICC) Damage Index (SDI). The dependent variable was the change in SDI score between study visits. Predictors were from the preceding visit. Variables known to affect damage accrual in SLE were included in the analyses. RESULTS: Three hundred and fifty-two patients (82 Hispanics, 153 African-Americans and 117 Caucasians) representing 1795 patient visits were included. Previous damage was found to be a significant predictor of subsequent damage accrual (P < 0.0001). Other variables predictive of subsequent damage accrual were disease activity (P < 0.0001), older age (P = 0.041) and use of corticosteroids (P = 0.0048). CONCLUSIONS: Once damage occurs in SLE, further damage is expected to occur. This is more likely to be the case if disease activity persists. These data have clinical implications for the management of SLE patients.     

Mean and variance of single photon counting with deadtime

The statistics of photon counting by systems affected by deadtime are potentially important for statistical image reconstruction methods. We present a new way of analysing the moments of the counting process for a counter system affected by various models of deadtime related to PET and SPECT imaging. We derive simple and exact expressions for the first and second moments of the number of recorded events under various models. From our mean expression for a SPECT deadtime model, we derive a simple estimator for the actual intensity of the underlying Poisson process; simulations show that our estimator is unbiased even for extremely high count rates. From this analysis, we study the suitability of the Poisson statistical model assumed in most statistical image reconstruction algorithms. For systems containing 'modules' with several detector elements, where each element can cause deadtime losses for the entire module, such as block PET detectors or Anger cameras, the Poisson statistical model appears to be adequate even in the presence of deadtime losses.     

Pseudoparadoxical impulsivity in restrictive anorexia nervosa: a consequence of the logic of scarcity

OBJECTIVE: To explain an apparently paradoxical pattern wherein sufferers of restrictive anorexia nervosa exhibit both rigorous self-restraint and episodic impulsivity. METHOD: The experimental, historical, and clinical literatures were examined for evidence of psychological and behavioral changes accompanying severe dietary constriction; such changes were noted and compared with those reported to occur in anorexics. RESULTS: Increased impulsivity in association with dietary constriction is described in diverse literatures. A number of lines of evidence suggest that the serotonergic system mediates this change. DISCUSSION: Many forms of impulsivity can be understood as having once constituted fitness-enhancing responses to resource scarcity. It is suggested that an evolved psychological mechanism calibrates the individual's sensitivity to risk in light of future prospects. Self-injurious behaviors are explicable as misfirings of such a mechanism. Similarly, excessive exercising by anorexics may reflect the misdirection of reward systems that normally encourage adaptive increases in ranging behavior under conditions of scarcity.     

Systemic lupus erythematosus in three ethnic groups. XII. Risk factors for lupus nephritis after diagnosis

The purpose of this study was to determine the cumulative incidence of lupus nephritis (LN) and the factors predictive of its occurrence in a multiethnic systemic lupus erythematosus (SLE) cohort. We studied 353 SLE patients as defined by the American College of Rheumatology (ACR) criteria (65 Hispanics, 93 African-Americans and 91 Caucasians). First, we determined the cumulative incidence of LN in all patients. Next, we determined the predictors for LN in those with nephritis occurring after diagnosis. The dependent variable, LN, was defined by: (1) A renal biopsy demonstrating World Health Organization (WHO), class II-V histopathology; and/or (2) proteinuria > or = 0.5 g/24 h or 3+ proteinuria attributable to SLE; and/or (3) one of the following features also attributable to SLE and present on two or more visits, which were performed at least 6 months apart--proteinuria > or = 2+, serum creatinine > or = 1.4 mg/dl, creatinine clearance < or = 79 ml/min, > or = 10 RBCs or WBCs per high power field (hpf), or > or = 3 granular or cellular casts per hpf. Independent variables assessed at diagnosis, and if absent, at baseline, were from four domains: sociodemographic, clinical, immunologic and immunogenetic (including the complete antibody profile and MHC class II alleles), and health habits. Variables with P < 0.05 by chi square analyses were entered into domain-specific stepwise logistic regression analyses controlling for disease duration, with LN as the dependent variable. Significant domain-specific regression variables (P < or = 0.1) were then entered into an overall model. The cumulative incidence of LN was 54.3% in all patients, and 35.3% for those developing LN after diagnosis. LN after diagnosis occurred in 43.1% of 65 Hispanics, 50.5% of 93 African-Americans, and 14.3% of 91 Caucasians, P < 0.0001. The duration of follow-up for those with LN after diagnosis was 5.5+/-2.4 vs 4.0+/-2.9 years for those without LN. Hispanic (odds ratio (OR) = 2.71, 95% confidence limits (CL) = 1.07-6.87, P < 0.04) and African-American ethnicities (OR = 3.13, 95% CL = 1.21-8.09, P < 0.02), not married or living together (OR = 3.45, 95% CL = 1.69-7.69, P < 0.0003), higher SLAM score (OR = 1.11, 95% CL = 1.02-1.19, P < 0.007), anti-dsDNA (OR = 3.14, 95% CL = 1.50-6.57, P < 0.0001) and anti-RNP (OR = 4.24, CL = 1.98-9.07, P < 0.0001) antibodies were shown to be significant predictors of the occurrence of LN. Repeated analyses excluding the patients with missing HLA data showed that absence of HLA-DQB1*0201 was also a significant predictor for the occurrence of LN (OR = 2.34, CL = 1.13-5.26, P < 0.04). In conclusion, LN occurred significantly more often in Hispanics and African-Americans with SLE. Sociodemographic, clinical and immunologic/immunogenetic factors seem to be predictive of LN occurring after the diagnosis of SLE has been made.