Hayes OG. J Res Med Sci. 2018 May 30;23:39.

Hayes OG et al., conducted a study which determined whether serum levels of procollagen type 1 N propeptide (P1NP), a bone formation turnover marker, differed between diabetic foot ulcer with osteomyelitis (DFO) and diabetic foot ulcers without osteomyelitis serving as controls. The usefulness of P1NP in diagnosing DFO compared to other common inflammatory markers was also get assessed. A total of 27 patients (16 DFO and 11 controls) aged >18 with a diabetic foot ulcer with and without osteomyelitis (DFO) and controls were included. Firstly detailed history and clinical examination were conducted and a protocol was completed. Morning fasting venous blood samples were taken, which was centrifuged at 3000 g for 5 min, followed by −80°C storage. The My BioSource enzyme-linked immunosorbent assay kit measured serum P1NP concentration. The means between the two groups was compared by student’s t-test. The Chi-squared test/Fisher’s exact test evaluated the association between categorical variable.

Results observed were:

  • Mean serum P1NP levels were consequently higher in the DFO group (n: 16), 10.5 ± 5.2 (ng/ml), compared to lower values in the control group (n: 11) 3.1 ± 2.8 (ng/ml), p = 0.001

Figure 1: Higher serum procollagen type 1 N propeptide concentration in patients with diabetic foot osteomyelitis compared to control group. p < 0.0001

  • P1NP showed the highest combination of sensitivity/specificity 86.7%/80% compared to 70.6%/80%, 56.2%/45.4%, and 50%/37% for C-reactive protein (CRP), white blood cells (WBCs), and platelets, resp.

 

Figure 2: Higher combination of sensitivity/specificity in procollagen type 1 N propeptide (P1NP) compared to C-reactive protein (CRP), white blood cells (WBCs), platelets

 

  • For the diagnosis of DFO the positive and negative predictive values of P1NP were similarly higher 86.7% and 80.0%, resp. with the positive diagnostic test cut off of ≥ 4.42 (ng/ml)
  • The best value of AUC of 0.9 for P1NP showed by Receiver operator characteristic (ROC) curves compared to 0.85, 0.54, and 0.46 for CRP, WBC, and platelets

Figure 3: Receiver operator characteristic curves showing best value for procollagen type 1 N propeptide in diagnosing diabetic foot osteomyelitis compared to other three tests – white blood counts, Creactive protein, and platelets

Thus, it was concluded that P1NP showed significant diagnostic utility in ruling in and ruling out DFO better than other tested nonspecific inflammatory markers, and thus requires more investigations.