Background/Purpose:

National Health and Nutrition Survey III (1988-94,USA) data showed a low K+ body status in RA. Further information is scanty. K+ is critical to ‘pain’ [nociceptive processing, K+ ion channel downregulation (Tsantoulas. Trends Neurosci 2014; 37:146) and related process e.g. oxidant tissue damage and T lymphocytes function [K2P5.1 (Bitner. Arthritis Res Therapy 2011;13:R 21), Kv1.3 & KCa3.1 channels (Lam. Drug Dev Res 2011; 72: 573] and cortisol secretion. Using Indian standards (National Institute of Nutrition, Hyderabad) and controlled diet survey, we showed that K+ was low (p<0.5) in RA patients, more so in women (EULAR 2014).

Methods: 172 consenting chronic RA patients (ACR 1987 classified, mean age 49.9 years, 89 % women, mean duration 9.9 years,74% seropositive RF) with active pain(visual analogue scale > 4 cm) were randomized into an assessor blind, three arm study of 16 week duration in a community rheumatology center. Standardized oral K+ intake was based on K+ rich vegetarian balanced diet in Arm A (3.5-4 gm K+ daily) and an additional K+ supplement powder (K+ rich pulses & seeds plus oral rehydration salt(3 gm K+), Indian pharmacopeia) in Arm B (7.5-8 gm K+ daily); local diet preferences considered. Arm C was control (routine diet , 2-3 gm K+ daily). Patients continued pre-study suprvised standard rheumatology care/drugs (72% methotrexate, mean weekly dose 14 mg;60% prednisolone, mean4 mg daily); analgesic rescue permitted and monitored as per protocol. No other non-drug intervention advised. Standard efficacy/safety measures and diet intake were evaluated every month. Compliance check included urinary K+ assay. The study (80% power, significant p <0.05) was analyzed using SPSS; NS: p, not significant. Arms were well matched for several measures (for mean DAS 28: A=4.9; B=5.5; C=4.9) and withdrawals (A: 8.8%; B:12.1%; C: 8.8%).  

Results:

Pain and several ACR efficacy measures improved (P<0.05) by intervention; difference was NS by intent to treat analysis/ITT (mean change pain VAS: A=-1.3 cm; B=2 cm; C= 1.2; p=0.17, ANOVA).But completer analysis showed significant change (p=0.04) in mean pain VAS in the B intervention arm (high K+ intake). B arm also showed best response (ITT, P<0.05) in proportion patients with at least 50% reduction and minimal clinical important difference in pain VAS on completion from baseline. Maximum improvement (NS) in HAQ (Indian validated version) and SF 36 physical score was seen in the B arm. There was reduction (NS) in the mean DAS 28 score by intervention (A:-1.4; B:-1.2; C: -0.9). Only mild AE were reported (<8% patients by study arm). On completion, B arm demonstrated a maximum serum cortisol (AM) increase. K+ intervention arms showed reduction in systolic BP. Ongoing medication, dietary factors and compliance, disease activity status may confound results.

Conclusion:

This pragmatic interventional control study in patients suffering from  chronic symptomatic RA  showed a clinically important pain reduction over and above standard drug treatment using dietary K+ augmentation. Other possible benefits were reduced disease activity and improved BP (cardiovascular) status. Overall, this seemed to be a gentle useful and safe adjunct therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/oral-potassium-k-reduces-pain-in-ra-a-randomized-active-control-study-of-diet-based-k-intervention/