Differences in dietary intake assessed by dietary recall and that estimated by protein nitrogen appearance rate.

Abstract

Peritoneal dialysis (PD) patients are at risk of muscle wasting and clinical guidelines recommend assessing dietary intake, by calculating protein equivalent of nitrogen appearance (PNA) to assure adequate intake. As the PNA equations were developed some time ago based on continuous ambulatory PD (CAPD) treatments, we re-evaluated them by comparing dietary recall protein intake. Dietary histories were obtained from 42 PD patients, mean age 62.2 ± 15.8 years, 58.1% male, 41.9% white, 39.5% treated with CAPD, median dialysis vintage 13.2 (3.1-23.3) months when attending for routine outpatient peritoneal membrane testing. Dietary protein intake (DPI), median 50.8 (37.5-71.5) g/day was determined with the Nutrics software program, and using PNA equations, DPI varied from 32.6 (31-34.3) to 68.8 (58.7-86.3) g/day. Bland Altman bias ranged from -22.8 ± 23.4 to +12.0 ± 24.6 g/day, with the older equations tending to underestimate and the more recent equations overestimating dietary recall DPI. There was systematic bias with the older equations, particularly as DPI increased. Although there was a wide variation, the two equations exhibiting least variation with dietary DPI were: PNA=15.1 + (0.195 × 24-h combined urinary and peritoneal urea mmol) + (24-h combined urinary and peritoneal protein loss), and PNA = 20.1 + (0.209 × 24-h combined urinary and peritoneal urea mmol), with a mean bias of +6.3 and +7.8 g/day compared to dietary DPI, and negative nitrogen balance of -1.7 and 2.6 g/day, respectively. Our study would suggest that the most used PNA equations may overestimate DPI in many patients and potentially result in unrecognised protein malnutrition.

AI evidence extraction

Main findings

In 42 PD patients, PNA-based estimates of dietary protein intake varied widely compared with dietary recall, with older PNA equations tending to underestimate and more recent equations tending to overestimate dietary recall DPI. The authors report systematic bias (especially for older equations at higher DPI) and suggest commonly used PNA equations may overestimate DPI in many patients, potentially leading to unrecognised protein malnutrition.

Outcomes measured

• Dietary protein intake (DPI) by dietary recall (Nutrics software)
• DPI estimated by protein equivalent of nitrogen appearance (PNA) equations
• Agreement/bias between dietary recall DPI and PNA-estimated DPI (Bland-Altman bias)
• Nitrogen balance

Limitations

• Single-center/outpatient sample not stated as representative
• Dietary intake assessed by recall/software (potential measurement error)
• Only 42 participants

{
    "study_type": "cross_sectional",
    "exposure": {
        "band": null,
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Peritoneal dialysis (PD) patients attending routine outpatient peritoneal membrane testing",
    "sample_size": 42,
    "outcomes": [
        "Dietary protein intake (DPI) by dietary recall (Nutrics software)",
        "DPI estimated by protein equivalent of nitrogen appearance (PNA) equations",
        "Agreement/bias between dietary recall DPI and PNA-estimated DPI (Bland-Altman bias)",
        "Nitrogen balance"
    ],
    "main_findings": "In 42 PD patients, PNA-based estimates of dietary protein intake varied widely compared with dietary recall, with older PNA equations tending to underestimate and more recent equations tending to overestimate dietary recall DPI. The authors report systematic bias (especially for older equations at higher DPI) and suggest commonly used PNA equations may overestimate DPI in many patients, potentially leading to unrecognised protein malnutrition.",
    "effect_direction": "mixed",
    "limitations": [
        "Single-center/outpatient sample not stated as representative",
        "Dietary intake assessed by recall/software (potential measurement error)",
        "Only 42 participants"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "peritoneal dialysis",
        "dietary protein intake",
        "dietary recall",
        "protein equivalent of nitrogen appearance",
        "PNA equations",
        "Bland-Altman",
        "nitrogen balance",
        "protein malnutrition"
    ],
    "suggested_hubs": []
}

Comments

Log in to comment.

No comments yet.