Validation of ICD-9-CM diagnosis codes for surgical site infection and noninfectious wound complications after mastectomy

BACKGROUNDFew studies have validated ICD-9-CM diagnosis codes for surgical site infection (SSI), and none have validated coding for noninfectious wound complications after mastectomy.OBJECTIVESTo determine the accuracy of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes in health insurer claims data to identify SSI and noninfectious wound complications, including hematoma, seroma, fat and tissue necrosis, and dehiscence, after mastectomy.METHODSWe reviewed medical records for 275 randomly selected women who were coded in the claims data for mastectomy with or without immediate breast reconstruction and had an ICD-9-CM diagnosis code for a wound complication within 180 days after surgery. We calculated the positive predictive value (PPV) to evaluate the accuracy of diagnosis codes in identifying specific wound complications and the PPV to determine the accuracy of coding for the breast surgical procedure.RESULTSThe PPV for SSI was 57.5%, or 68.9% if cellulitis-alone was considered an SSI, while the PPV for cellulitis was 82.2%. The PPVs of individual noninfectious wound complications ranged from 47.8% for fat necrosis to 94.9% for seroma and 96.6% for hematoma. The PPVs for mastectomy, implant, and autologous flap reconstruction were uniformly high (97.5%–99.2%).CONCLUSIONSOur results suggest that claims data can be used to compare rates of infectious and noninfectious wound complications after mastectomy across facilities, even though PPVs vary by specific type of postoperative complication. The accuracy of coding was highest for cellulitis, hematoma, and seroma, and a composite group of noninfectious complications (fat necrosis, tissue necrosis, or dehiscence).Infect Control Hosp Epidemiol 2017;38:334–339</jats:sec

Renormalised four-point coupling constant in the three-dimensional O(N) model with N=0

We simulate self-avoiding walks on a cubic lattice and determine the second virial coefficient for walks of different lengths. This allows us to determine the critical value of the renormalized four-point coupling constant in the three-dimensional N-vector universality class for N=0. We obtain g* = 1.4005(5), where g is normalized so that the three-dimensional field-theoretical beta-function behaves as \beta(g) = - g + g^2 for small g. As a byproduct, we also obtain precise estimates of the interpenetration ratio Psi*, Psi* = 0.24685(11), and of the exponent \nu, \nu = 0.5876(2).Comment: 16 page

Prevalence and predictors of postdischarge antibiotic use following mastectomy

OBJECTIVESurvey results suggest that prolonged administration of prophylactic antibiotics is common after mastectomy with reconstruction. We determined utilization, predictors, and outcomes of postdischarge prophylactic antibiotics after mastectomy with or without immediate breast reconstruction.DESIGNRetrospective cohort.PATIENTSCommercially insured women aged 18–64 years coded for mastectomy from January 2004 to December 2011 were included in the study. Women with a preexisting wound complication or septicemia were excluded.METHODSPredictors of prophylactic antibiotics within 5 days after discharge were identified in women with 1 year of prior insurance enrollment; relative risks (RR) were calculated using generalized estimating equations.RESULTSOverall, 12,501 mastectomy procedures were identified; immediate reconstruction was performed in 7,912 of these procedures (63.3%). Postdischarge prophylactic antibiotics were used in 4,439 procedures (56.1%) with immediate reconstruction and 1,053 procedures (22.9%) without immediate reconstruction (P&lt;.001). The antibiotics most commonly prescribed were cephalosporins (75.1%) and fluoroquinolones (11.1%). Independent predictors of postdischarge antibiotics were implant reconstruction (RR, 2.41; 95% confidence interval [CI], 2.23–2.60), autologous reconstruction (RR, 2.17; 95% CI, 1.93–2.45), autologous reconstruction plus implant (RR, 2.11; 95% CI, 1.92–2.31), hypertension (RR, 1.05; 95% CI, 1.00–1.10), tobacco use (RR, 1.07; 95% CI, 1.01–1.14), surgery at an academic hospital (RR, 1.14; 95% CI, 1.07–1.21), and receipt of home health care (RR, 1.11; 95% CI, 1.04–1.18). Postdischarge prophylactic antibiotics were not associated with SSI after mastectomy with or without immediate reconstruction (bothP&gt;.05).CONCLUSIONSProphylactic postdischarge antibiotics are commonly prescribed after mastectomy; immediate reconstruction is the strongest predictor. Stewardship efforts in this population to limit continuation of prophylactic antibiotics after discharge are needed to limit antimicrobial resistance.Infect Control Hosp Epidemiol2017;38:1048–1054</jats:sec

Experimental mathematics on the magnetic susceptibility of the square lattice Ising model

We calculate very long low- and high-temperature series for the susceptibility $\chi$ of the square lattice Ising model as well as very long series for the five-particle contribution $\chi^{(5)}$ and six-particle contribution $\chi^{(6)}$. These calculations have been made possible by the use of highly optimized polynomial time modular algorithms and a total of more than 150000 CPU hours on computer clusters. For $\chi^{(5)}$ 10000 terms of the series are calculated {\it modulo} a single prime, and have been used to find the linear ODE satisfied by $\chi^{(5)}$ {\it modulo} a prime. A diff-Pad\'e analysis of 2000 terms series for $\chi^{(5)}$ and $\chi^{(6)}$ confirms to a very high degree of confidence previous conjectures about the location and strength of the singularities of the $n$-particle components of the susceptibility, up to a small set of ``additional'' singularities. We find the presence of singularities at $w=1/2$ for the linear ODE of $\chi^{(5)}$, and $w^2= 1/8$ for the ODE of $\chi^{(6)}$, which are {\it not} singularities of the ``physical'' $\chi^{(5)}$ and $\chi^{(6)},$ that is to say the series-solutions of the ODE's which are analytic at $w =0$. Furthermore, analysis of the long series for $\chi^{(5)}$ (and $\chi^{(6)}$) combined with the corresponding long series for the full susceptibility $\chi$ yields previously conjectured singularities in some $\chi^{(n)}$, $n \ge 7$. We also present a mechanism of resummation of the logarithmic singularities of the $\chi^{(n)}$ leading to the known power-law critical behaviour occurring in the full $\chi$, and perform a power spectrum analysis giving strong arguments in favor of the existence of a natural boundary for the full susceptibility $\chi$.Comment: 54 pages, 2 figure

Critical behavior of two-dimensional cubic and MN models in the five-loop renormalization-group approximation

The critical thermodynamics of the two-dimensional N-vector cubic and MN models is studied within the field-theoretical renormalization-group (RG) approach. The beta functions and critical exponents are calculated in the five-loop approximation and the RG series obtained are resummed using the Borel-Leroy transformation combined with the generalized Pad\'e approximant and conformal mapping techniques. For the cubic model, the RG flows for various N are investigated. For N=2 it is found that the continuous line of fixed points running from the XY fixed point to the Ising one is well reproduced by the resummed RG series and an account for the five-loop terms makes the lines of zeros of both beta functions closer to each another. For the cubic model with N\geq 3, the five-loop contributions are shown to shift the cubic fixed point, given by the four-loop approximation, towards the Ising fixed point. This confirms the idea that the existence of the cubic fixed point in two dimensions under N>2 is an artifact of the perturbative analysis. For the quenched dilute O(M) models ($MN$ models with N=0) the results are compatible with a stable pure fixed point for M\geq1. For the MN model with M,N\geq2 all the non-perturbative results are reproduced. In addition a new stable fixed point is found for moderate values of M and N.Comment: 26 pages, 3 figure

Incidence of surgical site infection following mastectomy with and without immediate reconstruction using private insurer claims data

OBJECTIVE: The National Healthcare Safety Network classifies breast operations as clean procedures with an expected 1–2% surgical site infection (SSI) incidence. We assessed differences in SSI incidence following mastectomy with and without immediate reconstruction in a large, geographically diverse population. DESIGN: Retrospective cohort study. PATIENTS: Commercially-insured women aged 18–64 years with ICD-9-CM procedure or CPT-4 codes for mastectomy from 1/1/2004–12/31/2011. METHODS: Incident SSIs within 180 days after surgery were identified by ICD-9-CM diagnosis codes. The incidence of SSI after mastectomy +/− immediate reconstruction was compared by the chi-square test. RESULTS: From 2004–2011, 18,696 mastectomy procedures among 18,085 women were identified, with immediate reconstruction in 10,836 (58%) procedures. The 180-day incidence of SSI following mastectomy with or without reconstruction was 8.1% (1,520/18,696). Forty-nine percent of SSIs were identified within 30 days post-mastectomy, 24.5% between 31–60 days, 10.5% between 61–90 days, and 15.7% between 91–180 days. The incidence of SSI was 5.0% (395/7,860) after mastectomy-only, 10.3% (848/8,217) after mastectomy plus implant, 10.7% (207/1,942) after mastectomy plus flap, and 10.3% (70/677) after mastectomy plus flap and implant (p<0.001). The SSI risk was higher after bilateral compared with unilateral mastectomy with (11.4% vs. 9.4%, p=0.001) and without (6.1% vs. 4.7%, p=0.021) immediate reconstruction. CONCLUSIONS: SSI incidence was two-fold higher after mastectomy with immediate reconstruction than after mastectomy alone. Only 49% of SSIs were coded within 30 days after operation. Our results suggest stratification by procedure type will facilitate comparison of SSI rates after breast operations between facilities

The stability of a cubic fixed point in three dimensions from the renormalization group

The global structure of the renormalization-group flows of a model with isotropic and cubic interactions is studied using the massive field theory directly in three dimensions. The four-loop expansions of the \bt-functions are calculated for arbitrary $N$. The critical dimensionality $N_c=2.89 \pm 0.02$ and the stability matrix eigenvalues estimates obtained on the basis of the generalized Pad$\acute{\rm e}$-Borel-Leroy resummation technique are shown to be in a good agreement with those found recently by exploiting the five-loop \ve-expansions.Comment: 18 pages, LaTeX, 5 PostScript figure

Stratification of surgical site infection by operative factors and comparison of infection rates after hernia repair

OBJECTIVE: The National Healthcare Safety Network does not risk adjust surgical site infection (SSI) rates after hernia repair by operative factors. We investigated whether operative factors are associated with risk of SSI after hernia repair. DESIGN: Retrospective cohort study. PATIENTS: Commercially-insured enrollees aged 6 months–64 years with ICD-9-CM procedure or CPT-4 codes for inguinal/femoral, umbilical, and incisional/ventral hernia repair procedures from 1/1/2004–12/31/2010. METHODS: SSIs within 90 days after hernia repair were identified by ICD-9-CM diagnosis codes. Chi-square and Fisher’s exact tests were used to compare SSI incidence by operative factors. RESULTS: A total of 119,973 hernia repair procedures were included in the analysis. The incidence of SSI differed significantly by anatomic site, with rates of 0.45% (352/77,666) for inguinal/femoral, 1.16% (288/24,917) for umbilical, and 4.11% (715/17,390) for incisional/ventral hernia repair. Within anatomic sites, the incidence of SSI was significantly higher for open versus laparoscopic inguinal/femoral (0.48% [295/61,142] versus 0.34% [57/16,524], p=0.020) and incisional/ventral (4.20% [701/16,699] versus 2.03% [14/691], p=0.005) hernia repairs. The rate of SSI was higher following procedures with bowel obstruction/necrosis than procedures without obstruction/necrosis for open inguinal/femoral (0.89% [48/5,422] versus 0.44% [247/55,720], p<0.001) and umbilical (1.57% [131/8,355] versus 0.95% [157/16,562], p<0.001), but not incisional/ventral hernia repair (4.01% [224/5,585] versus 4.16% [491/11,805], p=0.645). CONCLUSIONS: The incidence of SSI was highest after open procedures, incisional/ventral repairs, and hernia repairs with bowel obstruction/necrosis. Our findings suggest that stratification of hernia repair SSI rates by some operative factors may be important to facilitate accurate comparison of SSI rates between facilities